arlut.csd.Util

Class SharedStringBuffer

java.lang.Object

arlut.csd.Util.SharedStringBuffer

All Implemented Interfaces:

java.io.Serializable

public final class SharedStringBuffer
extends java.lang.Object
implements java.io.Serializable

A hack on java.lang.StringBuffer to allow an instance of StringBuffer to be effectively re-used without as much overhead. Also provides a public getValue() method to allow reusedStringBuffer's to be written out to disk without forcing a duplication of the char array.

Author:

Arthur van Hoff, Jonathan Abbey (jonabbey@arlut.utexas.edu)

See Also:

ByteArrayOutputStream, String, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private int	count The count is the number of characters in the buffer.
private static int	DEFAULTSIZE
(package private) static long	serialVersionUID
private char[]	value The value is used for character storage.

Constructor Summary

Constructors

Constructor and Description
SharedStringBuffer() Constructs a string buffer with no characters in it and an initial capacity of 16 characters.
SharedStringBuffer(int length) Constructs a string buffer with no characters in it and an initial capacity specified by the length argument.
SharedStringBuffer(java.lang.String str) Constructs a string buffer so that it represents the same sequence of characters as the string argument.

Method Summary

Methods

Modifier and Type	Method and Description
SharedStringBuffer	append(boolean b) Appends the string representation of the boolean argument to the string buffer.
SharedStringBuffer	append(char c) Appends the string representation of the char argument to this string buffer.
SharedStringBuffer	append(char[] str) Appends the string representation of the char array argument to this string buffer.
SharedStringBuffer	append(char[] str, int offset, int len) Appends the string representation of a subarray of the char array argument to this string buffer.
SharedStringBuffer	append(double d) Appends the string representation of the double argument to this string buffer.
SharedStringBuffer	append(float f) Appends the string representation of the float argument to this string buffer.
SharedStringBuffer	append(int i) Appends the string representation of the int argument to this string buffer.
SharedStringBuffer	append(long l) Appends the string representation of the long argument to this string buffer.
SharedStringBuffer	append(java.lang.Object obj) Appends the string representation of the Object argument to this string buffer.
SharedStringBuffer	append(java.lang.String str) Appends the string to this string buffer.
int	capacity() Returns the current capacity of the String buffer.
char	charAt(int index) Returns the character at a specific index in this string buffer.
private void	copy() Copies the buffer value.
void	ensureCapacity(int minimumCapacity) Ensures that the capacity of the buffer is at least equal to the specified minimum.
private void	expandCapacity(int minimumCapacity) This implements the expansion semantics of ensureCapacity but is unsynchronized for use internally by methods which are already synchronized.
void	getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Characters are copied from this string buffer into the destination character array dst.
char[]	getValue() Return direct access to the char[] array in this object.
SharedStringBuffer	insert(int offset, boolean b) Inserts the string representation of the boolean argument into this string buffer.
SharedStringBuffer	insert(int offset, char c) Inserts the string representation of the char argument into this string buffer.
SharedStringBuffer	insert(int offset, char[] str) Inserts the string representation of the char array argument into this string buffer.
SharedStringBuffer	insert(int offset, double d) Inserts the string representation of the double argument into this string buffer.
SharedStringBuffer	insert(int offset, float f) Inserts the string representation of the float argument into this string buffer.
SharedStringBuffer	insert(int offset, int i) Inserts the string representation of the second int argument into this string buffer.
SharedStringBuffer	insert(int offset, long l) Inserts the string representation of the long argument into this string buffer.
SharedStringBuffer	insert(int offset, java.lang.Object obj) Inserts the string representation of the Object argument into this string buffer.
SharedStringBuffer	insert(int offset, java.lang.String str) Inserts the string into this string buffer.
int	length() Returns the length (character count) of this string buffer.
SharedStringBuffer	reverse() The character sequence contained in this string buffer is replaced by the reverse of the sequence.
void	setCharAt(int index, char ch) The character at the specified index of this string buffer is set to ch.
void	setLength(int newLength) Sets the length of this String buffer.
java.lang.String	toString() Converts to a string representing the data in this string buffer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

DEFAULTSIZE

private static final int DEFAULTSIZE

See Also:

Constant Field Values

value

private char[] value

The value is used for character storage.

count

private int count

The count is the number of characters in the buffer.

Constructor Detail

SharedStringBuffer

public SharedStringBuffer()

Constructs a string buffer with no characters in it and an initial capacity of 16 characters.

SharedStringBuffer

public SharedStringBuffer(int length)

Constructs a string buffer with no characters in it and an initial capacity specified by the length argument.

Parameters:

length - the initial capacity.

Throws:

java.lang.NegativeArraySizeException - if the length argument is less than 0.

SharedStringBuffer

public SharedStringBuffer(java.lang.String str)

Constructs a string buffer so that it represents the same sequence of characters as the string argument. The initial capacity of the string buffer is 16 plus the length of the string argument.

Parameters:

str - the initial contents of the buffer.

Method Detail

length

public int length()

Returns the length (character count) of this string buffer.

Returns:

the number of characters in this string buffer.

capacity

public int capacity()

Returns the current capacity of the String buffer. The capacity is the amount of storage available for newly inserted characters; beyond which an allocation will occur.

Returns:

the current capacity of this string buffer.

copy

private final void copy()

Copies the buffer value. This is normally only called when shared is true. It should only be called from a synchronized method.

ensureCapacity

public void ensureCapacity(int minimumCapacity)

Ensures that the capacity of the buffer is at least equal to the specified minimum. If the current capacity of this string buffer is less than the argument, then a new internal buffer 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.

expandCapacity

private void expandCapacity(int minimumCapacity)

This implements the expansion semantics of ensureCapacity but is unsynchronized for use internally by methods which are already synchronized.

See Also:

ensureCapacity(int)

setLength

public void setLength(int newLength)

Sets the length of this String buffer. If the newLength argument is less than the current length of the string buffer, the string buffer is truncated to contain exactly the number of characters given by the newLength argument.

If the newLength argument is greater than or equal to the current length, sufficient null characters ('\u0000') are appended to the string buffer so that length becomes the newLength argument.

The newLength argument must be greater than or equal to 0.

Parameters:

newLength - the new length of the buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the newLength argument is invalid.

See Also:

length()

charAt

public char charAt(int index)

Returns the character at a specific index in this string buffer.

The first character of a string buffer is at index 0, the next at index 1, and so on, for array indexing.

The index argument must be greater than or equal to 0, and less than the length of this string buffer.

Parameters:

index - the index of the desired character.

Returns:

the character at the specified index of this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the index is invalid.

See Also:

length()

getChars

public void getChars(int srcBegin,
            int srcEnd,
            char[] dst,
            int dstBegin)

Characters are copied from this string buffer 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 in the string buffer.

srcEnd - stop copying at this offset in the string buffer.

dst - the array to copy the data into.

dstBegin - offset into dst.

Throws:

java.lang.StringIndexOutOfBoundsException - if there is an invalid index into the buffer.

setCharAt

public void setCharAt(int index,
             char ch)

The character at the specified index of this string buffer is set to ch.

The offset argument must be greater than or equal to 0, and less than the length of this string buffer.

Parameters:

index - the index of the character to modify.

ch - the new character.

Throws:

java.lang.StringIndexOutOfBoundsException - if the index is invalid.

See Also:

length()

append

public SharedStringBuffer append(java.lang.Object obj)

Appends the string representation of the Object argument to this string buffer.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string buffer.

Parameters:

obj - an Object.

Returns:

this string buffer.

See Also:

String.valueOf(java.lang.Object), append(java.lang.String)

append

public SharedStringBuffer append(java.lang.String str)

Appends the string to this string buffer.

The characters of the String argument are appended, in order, to the contents of this string buffer, increasing the length of this string buffer by the length of the argument.

Parameters:

str - a string.

Returns:

this string buffer.

append

public SharedStringBuffer append(char[] str)

Appends the string representation of the char array argument to this string buffer.

The characters of the array argument are appended, in order, to the contents of this string buffer. The length of this string buffer increases by the length of the argument.

Parameters:

str - the characters to be appended.

Returns:

this string buffer.

append

public SharedStringBuffer append(char[] str,
                        int offset,
                        int len)

Appends the string representation of a subarray of the char array argument to this string buffer.

Characters of the character array str, starting at index offset, are appended, in order, to the contents of this string buffer. The length of this string buffer increases by the value of len.

Parameters:

str - the characters to be appended.

offset - the index of the first character to append.

len - the number of characters to append.

Returns:

this string buffer.

append

public SharedStringBuffer append(boolean b)

Appends the string representation of the boolean argument to the string buffer.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string buffer.

Parameters:

b - a boolean.

Returns:

this string buffer.

See Also:

String.valueOf(boolean), append(java.lang.String)

append

public SharedStringBuffer append(char c)

Appends the string representation of the char argument to this string buffer.

The argument is appended to the contents of this string buffer. The length of this string buffer increases by 1.

Parameters:

c - a char.

Returns:

this string buffer.

append

public SharedStringBuffer append(int i)

Appends the string representation of the int argument to this string buffer.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string buffer.

Parameters:

i - an int.

Returns:

this string buffer.

See Also:

String.valueOf(int), append(java.lang.String)

append

public SharedStringBuffer append(long l)

Appends the string representation of the long argument to this string buffer.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string buffer.

Parameters:

l - a long.

Returns:

this string buffer.

See Also:

String.valueOf(long), append(java.lang.String)

append

public SharedStringBuffer append(float f)

Appends the string representation of the float argument to this string buffer.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string buffer.

Parameters:

f - a float.

Returns:

this string buffer.

See Also:

String.valueOf(float), append(java.lang.String)

append

public SharedStringBuffer append(double d)

Appends the string representation of the double argument to this string buffer.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string buffer.

Parameters:

d - a double.

Returns:

this string buffer.

See Also:

String.valueOf(double), append(java.lang.String)

insert

public SharedStringBuffer insert(int offset,
                        java.lang.Object obj)

Inserts the string representation of the Object argument into this string buffer.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this string buffer at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

obj - an Object.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

String.valueOf(java.lang.Object), insert(int, java.lang.String), length()

insert

public SharedStringBuffer insert(int offset,
                        java.lang.String str)

Inserts the string into this string buffer.

The characters of the String argument are inserted, in order, into this string buffer at the indicated offset. The length of this string buffer is increased by the length of the argument.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

str - a string.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

length()

insert

public SharedStringBuffer insert(int offset,
                        char[] str)

Inserts the string representation of the char array argument into this string buffer.

The characters of the array argument are inserted into the contents of this string buffer at the position indicated by offset. The length of this string buffer increases by the length of the argument.

Parameters:

offset - the offset.

str - a character array.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

insert

public SharedStringBuffer insert(int offset,
                        boolean b)

Inserts the string representation of the boolean argument into this string buffer.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this string buffer at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

b - a boolean.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

String.valueOf(boolean), insert(int, java.lang.String), length()

insert

public SharedStringBuffer insert(int offset,
                        char c)

Inserts the string representation of the char argument into this string buffer.

The second argument is inserted into the contents of this string buffer at the position indicated by offset. The length of this string buffer increases by one.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

c - a char.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

length()

insert

public SharedStringBuffer insert(int offset,
                        int i)

Inserts the string representation of the second int argument into this string buffer.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this string buffer at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

i - an int.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

String.valueOf(int), insert(int, java.lang.String), length()

insert

public SharedStringBuffer insert(int offset,
                        long l)

Inserts the string representation of the long argument into this string buffer.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this string buffer at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

l - a long.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

String.valueOf(long), insert(int, java.lang.String), length()

insert

public SharedStringBuffer insert(int offset,
                        float f)

Inserts the string representation of the float argument into this string buffer.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this string buffer at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

f - a float.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

String.valueOf(float), insert(int, java.lang.String), length()

insert

public SharedStringBuffer insert(int offset,
                        double d)

Inserts the string representation of the double argument into this string buffer.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this string buffer at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this string buffer.

Parameters:

offset - the offset.

d - a double.

Returns:

this string buffer.

Throws:

java.lang.StringIndexOutOfBoundsException - if the offset is invalid.

See Also:

String.valueOf(double), insert(int, java.lang.String), length()

reverse

public SharedStringBuffer reverse()

The character sequence contained in this string buffer is replaced by the reverse of the sequence.

Returns:

this string buffer.

toString

public java.lang.String toString()

Converts to a string representing the data in this string buffer. A new String object is allocated and initialized to contain the character sequence currently represented by this string buffer. This String is then returned. Subsequent changes to the string buffer do not affect the contents of the String.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the string buffer.

getValue

public final char[] getValue()

Return direct access to the char[] array in this object. It is the responsibility of the calling code to make sure that it is executing in a context in which no other code will touch this array or SharedStringBuffer while the the reference to this array is in use.