Java.lang.StringBuilder Class
Java.lang.StringBuilder Class
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Introduction
The java.lang.StringBuilder class is mutable sequence of characters. This provides an API compatible with StringBuffer, but with no guarantee of synchronization.
Class Declaration
Following is the declaration for java.lang.StringBuilder class &
public final class StringBuilder
extends Object
implements Serializable, CharSequence
Class constructors
Constructor & Description
StringBuilder()
This constructs a string builder with no characters in it and an initial capacity of 16 characters.
StringBuilder(CharSequence seq)
This constructs a string builder that contains the same characters as the specified CharSequence.
StringBuilder(int capacity)
This constructs a string builder with no characters in it and an initial capacity specified by the capacity argument.
StringBuilder(String str)
This constructs a string builder initialized to the contents of the specified string.
Class methods
Method & Description
This method appends the string representation of the boolean argument to the sequence.
This method appends the string representation of the char argument to this sequence.
This method appends the string representation of the char array argument to this sequence.
This method appends the string representation of a subarray of the char array argument to this sequence.
This method appends the specified character sequence to this Appendable.
This method appends a subsequence of the specified CharSequence to this sequence.
This method appends the string representation of the double argument to this sequence.
This method appends the string representation of the float argument to this sequence.
This method appends the string representation of the int argument to this sequence.
This method appends the string representation of the long argument to this sequence.
This method appends the string representation of the Object argument.
This method appends the specified string to this character sequence.
This method appends the specified StringBuffer to this sequence.
This method appends the string representation of the codePoint argument to this sequence.
This method returns the current capacity.
This method returns the char value in this sequence at the specified index.
This method returns the character (Unicode code point) at the specified index.
This method returns the character (Unicode code point) before the specified index.
This method returns the number of Unicode code points in the specified text range of this sequence.
This method removes the characters in a substring of this sequence.
This method removes the char at the specified position in this sequence.
This method ensures that the capacity is at least equal to the specified minimum.
Characters are copied from this sequence into the destination character array dst.
This method returns the index within this string of the first occurrence of the specified substring.
This method returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
This method inserts the string representation of the boolean argument into this sequence.
This method inserts the string representation of the char argument into this sequence.
This method inserts the string representation of the char array argument into this sequence.
This method inserts the string representation of a subarray of the str array argument into this sequence.
This method inserts the specified CharSequence into this sequence.
This method inserts a subsequence of the specified CharSequence into this sequence.
This method inserts the string representation of the double argument into this sequence.
This method inserts the string representation of the float argument into this sequence.
This method inserts the string representation of the second int argument into this sequence.
This method inserts the string representation of the long argument into this sequence.
This method inserts the string representation of the Object argument into this character sequence.
This method inserts the string into this character sequence.
This method returns the index within this string of the rightmost occurrence of the specified substring.
This method returns the index within this string of the last occurrence of the specified substring.
This method returns the length (character count).
This method returns the index within this sequence that is offset from the given index by codePointOffset code points.
This method replaces the characters in a substring of this sequence with characters in the specified String.
This method causes this character sequence to be replaced by the reverse of the sequence.
Character at the specified index is set to ch.
This method sets the length of the character sequence.
This method returns a new character sequence that is a subsequence of this sequence.
This method returns a new String that contains a subsequence of characters currently contained in this character sequence.
This method returns a new String that contains a subsequence of characters currently contained in this sequence.
This method returns a string representing the data in this sequence.
This method attempts to reduce storage used for the character sequence.
Methods inherited
This class inherits methods from the following classes &
java.lang.Object
java.lang.CharSequence
& Copyright 2017. All Rights Reserved.StringBuilder (Java Platform SE 7 )
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Class StringBuilder
java.lang.StringBuilder
All Implemented Interfaces:
public final class StringBuilder
implements ,
A mutable sequence of characters.
This class provides an API compatible
with StringBuffer, but with no guarantee of synchronization.
This class is designed for use as a drop-in replacement for
StringBuffer in places where the string buffer was being
used by a single thread (as is generally the case).
Where possible,
it is recommended that this class be used in preference to
StringBuffer as it will be faster under most implementations.
The principal operations on a StringBuilder are the
append and insert methods, which are
overloaded so as to accept data of any type. Each effectively
converts a given datum to a string and then appends or inserts the
characters of that string to the string builder. The
append method always adds these characters at the end
the insert method adds the characters at
a specified point.
For example, if z refers to a string builder object
whose current contents are "start", then
the method call z.append("le") would cause the string
builder to contain "startle", whereas
z.insert(4, "le") would alter the string builder to
contain "starlet".
In general, if sb refers to an instance of a StringBuilder,
then sb.append(x) has the same effect as
sb.insert(sb.length(),&x).
Every string builder has a capacity. As long as the length of the
character sequence contained in the string builder does not exceed
the capacity, it is not necessary to allocate a new internal
buffer. If the internal buffer overflows, it is automatically made larger.
Instances of StringBuilder are not safe for
use by multiple threads. If such synchronization is required then it is
recommended that
See Also:,
Constructor Summary
Constructors&
Constructor and Description
Constructs a string builder with no characters in it and an
initial capacity of 16 characters.
Constructs a string builder that contains the same characters
as the specified CharSequence.
(int&capacity)
Constructs a string builder with no characters in it and an
initial capacity specified by the capacity argument.
Constructs a string builder initialized to the contents of the
specified string.
Method Summary
Modifier and Type
Method and Description
(boolean&b)
Appends the string representation of the boolean
argument to the sequence.
Appends the string representation of the char
argument to this sequence.
(char[]&str)
Appends the string representation of the char array
argument to this sequence.
(char[]&str,
int&offset,
Appends the string representation of a subarray of the
char array argument to this sequence.
Appends the specified character sequence to this Appendable.
int&start,
Appends a subsequence of the specified CharSequence to this
(double&d)
Appends the string representation of the double
argument to this sequence.
Appends the string representation of the float
argument to this sequence.
Appends the string representation of the int
argument to this sequence.
(long&lng)
Appends the string representation of the long
argument to this sequence.
Appends the string representation of the Object argument.
Appends the specified string to this character sequence.
Appends the specified StringBuffer to this sequence.
(int&codePoint)
Appends the string representation of the codePoint
argument to this sequence.
Returns the current capacity.
(int&index)
Returns the char value in this sequence at the specified index.
(int&index)
Returns the character (Unicode code point) at the specified
(int&index)
Returns the character (Unicode code point) before the specified
(int&beginIndex,
int&endIndex)
Returns the number of Unicode code points in the specified text
range of this sequence.
(int&start,
Removes the characters in a substring of this sequence.
(int&index)
Removes the char at the specified position in this
(int&minimumCapacity)
Ensures that the capacity is at least equal to the specified minimum.
(int&srcBegin,
int&srcEnd,
char[]&dst,
int&dstBegin)
Characters are copied from this sequence into the
destination character array dst.
Returns the index within this string of the first occurrence of the
specified substring.
int&fromIndex)
Returns the index within this string of the first occurrence of the
specified substring, starting at the specified index.
(int&offset,
boolean&b)
Inserts the string representation of the boolean
argument into this sequence.
(int&offset,
Inserts the string representation of the char
argument into this sequence.
(int&offset,
char[]&str)
Inserts the string representation of the char array
argument into this sequence.
(int&index,
char[]&str,
int&offset,
Inserts the string representation of a subarray of the str
array argument into this sequence.
(int&dstOffset,
Inserts the specified CharSequence into this sequence.
(int&dstOffset,
int&start,
Inserts a subsequence of the specified CharSequence into
this sequence.
(int&offset,
Inserts the string representation of the double
argument into this sequence.
(int&offset,
Inserts the string representation of the float
argument into this sequence.
(int&offset,
Inserts the string representation of the second int
argument into this sequence.
(int&offset,
Inserts the string representation of the long
argument into this sequence.
(int&offset,
Inserts the string representation of the Object
argument into this character sequence.
(int&offset,
Inserts the string into this character sequence.
Returns the index within this string of the rightmost occurrence
of the specified substring.
int&fromIndex)
Returns the index within this string of the last occurrence of the
specified substring.
Returns the length (character count).
(int&index,
int&codePointOffset)
Returns the index within this sequence that is offset from the
given index by codePointOffset code
(int&start,
Replaces the characters in a substring of this sequence
with characters in the specified String.
Causes this character sequence to be replaced by the reverse of
the sequence.
(int&index,
The character at the specified index is set to ch.
(int&newLength)
Sets the length of the character sequence.
(int&start,
Returns a new character sequence that is a subsequence of this sequence.
(int&start)
Returns a new String that contains a subsequence of
characters currently contained in this character sequence.
(int&start,
Returns a new String that contains a subsequence of
characters currently contained in this sequence.
Returns a string representing the data in this sequence.
Attempts to reduce storage used for the character sequence.
Methods inherited from class&java.lang.
, , , , , , , , ,
Methods inherited from interface&java.lang.
Constructor Detail
StringBuilder
public&StringBuilder()
Constructs a string builder with no characters in it and an
initial capacity of 16 characters.
StringBuilder
public&StringBuilder(int&capacity)
Constructs a string builder with no characters in it and an
initial capacity specified by the capacity argument.
Parameters:capacity - the initial capacity.
- if the capacity
argument is less than 0.
StringBuilder
public&StringBuilder(&str)
Constructs a string builder initialized to the contents of the
specified string. The initial capacity of the string builder is
16 plus the length of the string argument.
Parameters:str - the initial contents of the buffer.
- if str is null
StringBuilder
public&StringBuilder(&seq)
Constructs a string builder that contains the same characters
as the specified CharSequence. The initial capacity of
the string builder is 16 plus the length of the
CharSequence argument.
Parameters:seq - the sequence to copy.
- if seq is null
Method Detail
public&&append(&obj)
Appends the string representation of the Object argument.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:obj - an Object.
Returns:a reference to this object.
public&&append(&str)
Appends the specified string to this character sequence.
The characters of the String argument are appended, in
order, increasing the length of this sequence by the length of the
argument. If str is null, then the four
characters "null" are appended.
Let n be the length of this character sequence just prior to
execution of the append method. Then the character at
index k in the new character sequence is equal to the character
at index k in the old character sequence, if k is less
than n; otherwise, it is equal to the character at index
k-n in the argument str.
Parameters:str - a string.
Returns:a reference to this object.
public&&append(&sb)
Appends the specified StringBuffer to this sequence.
The characters of the StringBuffer argument are appended,
in order, to this sequence, increasing the
length of this sequence by the length of the argument.
If sb is null, then the four characters
"null" are appended to this sequence.
Let n be the length of this character sequence just prior to
execution of the append method. Then the character at index
k in the new character sequence is equal to the character at
index k in the old character sequence, if k is less than
n; otherwise, it is equal to the character at index k-n
in the argument sb.
Parameters:sb - the StringBuffer to append.
Returns:a reference to this object.
public&&append(&s)
Description copied from interface:&
Appends the specified character sequence to this Appendable.
Depending on which class implements the character sequence
csq, the entire sequence may not be appended.
instance, if csq is a
the subsequence to append is defined by the buffer's position and limit.
Specified by:
&in interface&
Parameters:s - The character sequence to append.
null, then the four characters "null" are
appended to this Appendable.
Returns:A reference to this Appendable
public&&append(&s,
int&start,
Appends a subsequence of the specified CharSequence to this
Characters of the argument s, starting at
index start, are appended, in order, to the contents of
this sequence up to the (exclusive) index end. The length
of this sequence is increased by the value of end - start.
Let n be the length of this character sequence just prior to
execution of the append method. Then the character at
index k in this character sequence becomes equal to the
character at index k in this sequence, if k is less than
n; otherwise, it is equal to the character at index
k+start-n in the argument s.
If s is null, then this method appends
characters as if the s parameter was a sequence containing the four
characters "null".
Specified by:
&in interface&
Parameters:s - the sequence to append.start - the starting index of the subsequence to be appended.end - the end index of the subsequence to be appended.
Returns:a reference to this object.
start is negative, or
start is greater than end or
end is greater than s.length()
public&&append(char[]&str)
Appends the string representation of the char array
argument to this sequence.
The characters of the array argument are appended, in order, to
the contents of this sequence. The length of this sequence
increases by the length of the argument.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:str - the characters to be appended.
Returns:a reference to this object.
public&&append(char[]&str,
int&offset,
Appends the string representation of a subarray of the
char array argument to this sequence.
Characters of the char array str, starting at
index offset, are appended, in order, to the contents
of this sequence. The length of this sequence increases
by the value of len.
The overall effect is exactly as if the arguments were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:str - the characters to be appended.offset - the index of the first char to append.len - the number of chars to append.
Returns:a reference to this object.
- if offset & 0 or len & 0
or offset+len & str.length
public&&append(boolean&b)
Appends the string representation of the boolean
argument to the sequence.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:b - a boolean.
Returns:a reference to this object.
public&&append(char&c)
Appends the string representation of the char
argument to this sequence.
The argument is appended to the contents of this sequence.
The length of this sequence increases by 1.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the character in that string were then
to this character sequence.
Specified by:
&in interface&
Parameters:c - a char.
Returns:a reference to this object.
public&&append(int&i)
Appends the string representation of the int
argument to this sequence.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:i - an int.
Returns:a reference to this object.
public&&append(long&lng)
Appends the string representation of the long
argument to this sequence.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:lng - a long.
Returns:a reference to this object.
public&&append(float&f)
Appends the string representation of the float
argument to this sequence.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:f - a float.
Returns:a reference to this object.
public&&append(double&d)
Appends the string representation of the double
argument to this sequence.
The overall effect is exactly as if the argument were converted
to a string by the method ,
and the characters of that string were then
to this character sequence.
Parameters:d - a double.
Returns:a reference to this object.
appendCodePoint
public&&appendCodePoint(int&codePoint)
Appends the string representation of the codePoint
argument to this sequence.
The argument is appended to the contents of this sequence.
The length of this sequence increases by
The overall effect is exactly as if the argument were
converted to a char array by the method
and the character in that array
to this character
Parameters:codePoint - a Unicode code point
Returns:a reference to this object.Since:
public&&delete(int&start,
Removes the characters in a substring of this sequence.
The substring begins at the specified start and extends to
the character at index end - 1 or to the end of the
sequence if no such character exists. If
start is equal to end, no changes are made.
Parameters:start - The beginning index, inclusive.end - The ending index, exclusive.
Returns:This object.
- if start
is negative, greater than length(), or
greater than end.
deleteCharAt
public&&deleteCharAt(int&index)
Removes the char at the specified position in this
sequence. This sequence is shortened by one char.
Note: If the character at the given index is a supplementary
character, this method does not remove the entire character. If
correct handling of supplementary characters is required,
determine the number of chars to remove by calling
Character.charCount(thisSequence.codePointAt(index)),
where thisSequence is this sequence.
Parameters:index - Index of char to remove
Returns:This object.
- if the index
is negative or greater than or equal to
public&&replace(int&start,
Replaces the characters in a substring of this sequence
with characters in the specified String. The substring
begins at the specified start and extends to the character
at index end - 1 or to the end of the
sequence if no such character exists. First the
characters in the substring are removed and then the specified
String is inserted at start. (This
sequence will be lengthened to accommodate the
specified String if necessary.)
Parameters:start - The beginning index, inclusive.end - The ending index, exclusive.str - String that will replace previous contents.
Returns:This object.
- if start
is negative, greater than length(), or
greater than end.
public&&insert(int&index,
char[]&str,
int&offset,
Inserts the string representation of a subarray of the str
array argument into this sequence. The subarray begins at the
specified offset and extends len chars.
The characters of the subarray are inserted into this sequence at
the position indicated by index. The length of this
sequence increases by len chars.
Parameters:index - position at which to insert subarray.str - A char array.offset - the index of the first char in subarray to
be inserted.len - the number of chars in the subarray to
be inserted.
Returns:This object
- if index
is negative or greater than length(), or
offset or len are negative, or
(offset+len) is greater than
str.length.
public&&insert(int&offset,
Inserts the string representation of the Object
argument into this character sequence.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the characters of that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.obj - an Object.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&offset,
Inserts the string into this character sequence.
The characters of the String argument are inserted, in
order, into this sequence at the indicated offset, moving up any
characters originally above that position and increasing the length
of this sequence by the length of the argument. If
str is null, then the four characters
"null" are inserted into this sequence.
The character at index k in the new character sequence is
the character at index k in the old character sequence, if
k is less than offset
the character at index k-offset in the
argument str, if k is not less than
offset but is less than offset+str.length()
the character at index k-str.length() in the
old character sequence, if k is not less than
offset+str.length()
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.str - a string.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&offset,
char[]&str)
Inserts the string representation of the char array
argument into this sequence.
The characters of the array argument are inserted into the
contents of this sequence at the position indicated by
offset. The length of this sequence increases by
the length of the argument.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the characters of that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.str - a character array.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&dstOffset,
Inserts the specified CharSequence into this sequence.
The characters of the CharSequence argument are inserted,
in order, into this sequence at the indicated offset, moving up
any characters originally above that position and increasing the length
of this sequence by the length of the argument s.
The result of this method is exactly the same as if it were an
invocation of this object's
(dstOffset, s, 0, s.length())
If s is null, then the four characters
"null" are inserted into this sequence.
Parameters:dstOffset - the offset.s - the sequence to be inserted
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&dstOffset,
int&start,
Inserts a subsequence of the specified CharSequence into
this sequence.
The subsequence of the argument s specified by
start and end are inserted,
in order, into this sequence at the specified destination offset, moving
up any characters originally above that position. The length of this
sequence is increased by end - start.
The character at index k in this sequence becomes equal to:
the character at index k in this sequence, if
k is less than dstOffset
the character at index k+start-dstOffset in
the argument s, if k is greater than or equal to
dstOffset but is less than dstOffset+end-start
the character at index k-(end-start) in this
sequence, if k is greater than or equal to
dstOffset+end-start
The dstOffset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
The start argument must be nonnegative, and not greater than
The end argument must be greater than or equal to
start, and less than or equal to the length of s.
If s is null, then this method inserts
characters as if the s parameter was a sequence containing the four
characters "null".
Parameters:dstOffset - the offset in this sequence.s - the sequence to be inserted.start - the starting index of the subsequence to be inserted.end - the end index of the subsequence to be inserted.
Returns:a reference to this object.
- if dstOffset
is negative or greater than this.length(), or
start or end are negative, or
start is greater than end or
end is greater than s.length()
public&&insert(int&offset,
boolean&b)
Inserts the string representation of the boolean
argument into this sequence.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the characters of that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.b - a boolean.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&offset,
Inserts the string representation of the char
argument into this sequence.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the character in that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.c - a char.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&offset,
Inserts the string representation of the second int
argument into this sequence.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the characters of that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.i - an int.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&offset,
Inserts the string representation of the long
argument into this sequence.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the characters of that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.l - a long.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&offset,
Inserts the string representation of the float
argument into this sequence.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the characters of that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.f - a float.
Returns:a reference to this object.
- if the offset is invalid.
public&&insert(int&offset,
Inserts the string representation of the double
argument into this sequence.
The overall effect is exactly as if the second argument were
converted to a string by the method ,
and the characters of that string were then
into this character
sequence at the indicated offset.
The offset argument must be greater than or equal to
0, and less than or equal to the
of this sequence.
Parameters:offset - the offset.d - a double.
Returns:a reference to this object.
- if the offset is invalid.
public&int&indexOf(&str)
Returns the index within this string of the first occurrence of the
specified substring. The integer returned is the smallest value
k such that:
this.toString().startsWith(str, k)
Parameters:str - any string.
Returns:if the string argument occurs as a substring within this
object, then the index of the first character of the first
such s if it does not occur as a
substring, -1 is returned.
- if str is
public&int&indexOf(&str,
int&fromIndex)
Returns the index within this string of the first occurrence of the
specified substring, starting at the specified index.
The integer
returned is the smallest value k for which:
k >= Math.min(fromIndex, this.length()) &&
this.toString().startsWith(str, k)
If no such value of k exists, then -1 is returned.
Parameters:str - the substring for which to search.fromIndex - the index from which to start the search.
Returns:the index within this string of the first occurrence of the
specified substring, starting at the specified index.
- if str is
lastIndexOf
public&int&lastIndexOf(&str)
Returns the index within this string of the rightmost occurrence
of the specified substring.
The rightmost empty string "" is
considered to occur at the index value this.length().
The returned index is the largest value k such that
this.toString().startsWith(str, k)
Parameters:str - the substring to search for.
Returns:if the string argument occurs one or more times as a substring
within this object, then the index of the first character of
the last such substring is returned. If it does not occur as
a substring, -1 is returned.
- if str is
lastIndexOf
public&int&lastIndexOf(&str,
int&fromIndex)
Returns the index within this string of the last occurrence of the
specified substring. The integer returned is the largest value k
such that:
k <= Math.min(fromIndex, this.length()) &&
this.toString().startsWith(str, k)
If no such value of k exists, then -1 is returned.
Parameters:str - the substring to search for.fromIndex - the index to start the search from.
Returns:the index within this sequence of the last occurrence of the
specified substring.
- if str is
public&&reverse()
Causes this character sequence to be replaced by the reverse of
the sequence. If there are any surrogate pairs included in the
sequence, these are treated as single characters for the
reverse operation. Thus, the order of the high-low surrogates
is never reversed.
Let n be the character length of this character sequence
(not the length in char values) just prior to
execution of the reverse method. Then the
character at index k in the new character sequence is
equal to the character at index n-k-1 in the old
character sequence.
Note that the reverse operation may result in producing
surrogate pairs that were unpaired low-surrogates and
high-surrogates before the operation. For example, reversing
"&#92;uDC00&#92;uD800" produces "&#92;uD800&#92;uDC00" which is
a valid surrogate pair.
Returns:a reference to this object.
public&&toString()
Returns a string representing the data in this sequence.
A new String object is allocated and initialized to
contain the character sequence currently represented by this
object. This String is then returned. Subsequent
changes to this sequence do not affect the contents of the
Specified by:
&in interface&
Returns:a string representation of this sequence of characters.
public&int&length()
Returns the length (character count).
Specified by:
&in interface&
Returns:the length of the sequence of characters currently
represented by this object
public&int&capacity()
Returns the current capacity. The capacity is the amount of storage
available for newly inserted characters, beyond which an allocation
will occur.
Returns:the current capacity
ensureCapacity
public&void&ensureCapacity(int&minimumCapacity)
Ensures that the capacity is at least equal to the specified minimum.
If the current capacity is less than the argument, then a new internal
array is allocated with greater capacity. The new capacity is the
larger of:
The minimumCapacity argument.
Twice the old capacity, plus 2.
If the minimumCapacity argument is nonpositive, this
method takes no action and simply returns.
Parameters:minimumCapacity - the minimum desired capacity.
trimToSize
public&void&trimToSize()
Attempts to reduce storage used for the character sequence.
If the buffer is larger than necessary to hold its current sequence of
characters, then it may be resized to become more space efficient.
Calling this method may, but is not required to, affect the value
returned by a subsequent call to the
public&void&setLength(int&newLength)
Sets the length of the character sequence.
The sequence is changed to a new character sequence
whose length is specified by the argument. For every nonnegative
index k less than newLength, the character at
index k in the new character sequence is the same as the
character at index k in the old sequence if k is less
than the length of the ol otherwise, it is the
null character '&#92;u0000'.
In other words, if the newLength argument is less than
the current length, the length is changed to the specified length.
If the newLength argument is greater than or equal
to the current length, sufficient null characters
('&#92;u0000') are appended so that
length becomes the newLength argument.
The newLength argument must be greater than or equal
Parameters:newLength - the new length
newLength argument is negative.
public&char&charAt(int&index)
Returns the char value in this sequence at the specified index.
The first char value is at index 0, the next at index
1, and so on, as in array indexing.
The index argument must be greater than or equal to
0, and less than the length of this sequence.
If the char value specified by the index is a
, the surrogate
value is returned.
Specified by:
&in interface&
Parameters:index - the index of the desired char value.
Returns:the char value at the specified index.
- if index is
negative or greater than or equal to length().
codePointAt
public&int&codePointAt(int&index)
Returns the character (Unicode code point) at the specified
index. The index refers to char values
(Unicode code units) and ranges from 0 to
If the char value specified at the given index
is in the high-surrogate range, the following index is less
than the length of this sequence, and the
char value at the following index is in the
low-surrogate range, then the supplementary code point
corresponding to this surrogate pair is returned. Otherwise,
the char value at the given index is returned.
Parameters:index - the index to the char values
Returns:the code point value of the character at the
- if the index
argument is negative or not less than the length of this
codePointBefore
public&int&codePointBefore(int&index)
Returns the character (Unicode code point) before the specified
index. The index refers to char values
(Unicode code units) and ranges from 1 to .
If the char value at (index - 1)
is in the low-surrogate range, (index - 2) is not
negative, and the char value at (index -
2) is in the high-surrogate range, then the
supplementary code point value of the surrogate pair is
returned. If the char value at index -
1 is an unpaired low-surrogate or a high-surrogate, the
surrogate value is returned.
Parameters:index - the index following the code point that should be returned
Returns:the Unicode code point value before the given index.
- if the index
argument is less than 1 or greater than the length
of this sequence.
codePointCount
public&int&codePointCount(int&beginIndex,
int&endIndex)
Returns the number of Unicode code points in the specified text
range of this sequence. The text range begins at the specified
beginIndex and extends to the char at
index endIndex - 1. Thus the length (in
chars) of the text range is
endIndex-beginIndex. Unpaired surrogates within
this sequence count as one code point each.
Parameters:beginIndex - the index to the first char of
the text range.endIndex - the index after the last char of
the text range.
Returns:the number of Unicode code points in the specified text
beginIndex is negative, or endIndex
is larger than the length of this sequence, or
beginIndex is larger than endIndex.
offsetByCodePoints
public&int&offsetByCodePoints(int&index,
int&codePointOffset)
Returns the index within this sequence that is offset from the
given index by codePointOffset code
points. Unpaired surrogates within the text range given by
index and codePointOffset count as
one code point each.
Parameters:index - the index to be offsetcodePointOffset - the offset in code points
Returns:the index within this sequence
- if index
is negative or larger then the length of this sequence,
or if codePointOffset is positive and the subsequence
starting with index has fewer than
codePointOffset code points,
or if codePointOffset is negative and the subsequence
before index has fewer than the absolute value of
codePointOffset code points.
public&void&getChars(int&srcBegin,
int&srcEnd,
char[]&dst,
int&dstBegin)
Characters are copied from this sequence into the
destination character array dst. The first character to
be copied is at index srcBegin; the last character to
be copied is at index srcEnd-1. The total number of
characters to be copied is srcEnd-srcBegin. The
characters are copied into the subarray of dst starting
at index dstBegin and ending at index:
dstbegin + (srcEnd-srcBegin) - 1
Parameters:srcBegin - start copying at this offset.srcEnd - stop copying at this offset.dst - the array to copy the data into.dstBegin - offset into dst.
- if dst is
- if any of the following is true:
srcBegin is negative
dstBegin is negative
the srcBegin argument is greater than
the srcEnd argument.
srcEnd is greater than
this.length().
dstBegin+srcEnd-srcBegin is greater than
dst.length
public&void&setCharAt(int&index,
The character at the specified index is set to ch. This
sequence is altered to represent a new character sequence that is
identical to the old character sequence, except that it contains the
character ch at position index.
The index argument must be greater than or equal to
0, and less than the length of this sequence.
Parameters:index - the index of the character to modify.ch - the new character.
- if index is
negative or greater than or equal to length().
public&&substring(int&start)
Returns a new String that contains a subsequence of
characters currently contained in this character sequence. The
substring begins at the specified index and extends to the end of
this sequence.
Parameters:start - The beginning index, inclusive.
Returns:The new string.
- if start is
less than zero, or greater than the length of this object.
subSequence
public&&subSequence(int&start,
Returns a new character sequence that is a subsequence of this sequence.
An invocation of this method of the form
sb.subSequence(begin,&end)
behaves in exactly the same way as the invocation
sb.substring(begin,&end)
This method is provided so that this class can
implement the
interface.
Specified by:
&in interface&
Parameters:start - the start index, inclusive.end - the end index, exclusive.
Returns:the specified subsequence.
- if start or end are negative,
if end is greater than length(),
or if start is greater than end
public&&substring(int&start,
Returns a new String that contains a subsequence of
characters currently contained in this sequence. The
substring begins at the specified start and
extends to the character at index end - 1.
Parameters:start - The beginning index, inclusive.end - The ending index, exclusive.
Returns:The new string.
- if start
or end are negative or greater than
length(), or start is
greater than end.
For further API reference and developer documentation, see . That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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