Module java.base
Package java.io

Class StringWriter

java.lang.Object
java.io.Writer
java.io.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
  • Constructor Details

    • 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
  • Method Details

    • 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