Class StringWriter

All Implemented Interfaces:
Closeable, Flushable, Appendable, AutoCloseable 
public class StringWriter
extends Writer

A character stream that collects its output in a string buffer, which can then be used to construct a string.

Closing a StringWriter has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

Since:
1.1

Fields

Fields declared in class java.io.Writer

lock

Constructors

Constructor Description
StringWriter()

Create a new string writer using the default initial string-buffer size.
StringWriter​(int initialSize)

Create a new string writer using the specified initial string-buffer size.

Methods

Modifier and Type Method Description
StringWriter append​(char c)

Appends the specified character to this writer.
StringWriter append​(CharSequence csq)

Appends the specified character sequence to this writer.
StringWriter append​(CharSequence csq, int start, int end)

Appends a subsequence of the specified character sequence to this writer.
void close()

Closing a StringWriter has no effect.
void flush()

Flush the stream.
StringBuffer getBuffer()

Return the string buffer itself.
String toString()

Return the buffer's current value as a string.
void write​(char[] cbuf, int off, int len)

Write a portion of an array of characters.
void write​(int c)

Write a single character.
void write​(String str)

Write a string.
void write​(String str, int off, int len)

Write a portion of a string.

Methods declared in class java.io.Writer

nullWriter, write

Methods declared in class java.lang.Object

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

Constructors

StringWriter

public StringWriter()

Create a new string writer using the default initial string-buffer size.

StringWriter

public StringWriter(int initialSize)

Create a new string writer using the specified initial string-buffer size.

Parameters:
initialSize - The number of char values that will fit into this buffer before it is automatically expanded
Throws:
IllegalArgumentException - If initialSize is negative

Methods

write

public void write(int c)

Write a single character.

Overrides:
write in class Writer
Parameters:
c - int specifying a character to be written

write

public void write(char[] cbuf,
                  int off,
                  int len)

Write a portion of an array of characters.

Specified by:
write in class Writer
Parameters:
cbuf - Array of characters
off - Offset from which to start writing characters
len - Number of characters to write
Throws:
IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given array

write

public void write(String str)

Write a string.

Overrides:
write in class Writer
Parameters:
str - String to be written

write

public void write(String str,
                  int off,
                  int len)

Write a portion of a string.

Overrides:
write in class Writer
Parameters:
str - String to be written
off - Offset from which to start writing characters
len - Number of characters to write
Throws:
IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given string

append

public StringWriter append(CharSequence csq)

Appends the specified character sequence to this writer.

An invocation of this method of the form out.append(csq) behaves in exactly the same way as the invocation 

out.write(csq.toString())

Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking the toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.

Specified by:
append in interface Appendable
Overrides:
append in class Writer
Parameters:
csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.
Returns:
This writer
Since:
1.5

append

public StringWriter append(CharSequence csq,
                           int start,
                           int end)

Appends a subsequence of the specified character sequence to this writer.

An invocation of this method of the form out.append(csq, start, end) when csq is not null, behaves in exactly the same way as the invocation 

out.write(csq.subSequence(start, end).toString())
Specified by:
append in interface Appendable
Overrides:
append in class Writer
Parameters:
csq - The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".
start - The index of the first character in the subsequence
end - The index of the character following the last character in the subsequence
Returns:
This writer
Throws:
IndexOutOfBoundsException - If start or end are negative, start is greater than end, or end is greater than csq.length()
Since:
1.5

append

public StringWriter append(char c)

Appends the specified character to this writer.

An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation 

out.write(c)
Specified by:
append in interface Appendable
Overrides:
append in class Writer
Parameters:
c - The 16-bit character to append
Returns:
This writer
Since:
1.5

toString

public String toString()

Return the buffer's current value as a string.

Overrides:
toString in class Object
Returns:
a string representation of the object.

getBuffer

public StringBuffer getBuffer()

Return the string buffer itself.

Returns:
StringBuffer holding the current buffer value.

flush

public void flush()

Flush the stream.

Specified by:
flush in interface Flushable
Specified by:
flush in class Writer

close

public void close()
           throws IOException

Closing a StringWriter has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

Specified by:
close in interface AutoCloseable
Specified by:
close in interface Closeable
Specified by:
close in class Writer
Throws:
IOException - If an I/O error occurs

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/io/StringWriter.html