Module java.base
Package java.io

Class StringWriter

  • All Implemented Interfaces:
    Closeable,Flushable,Appendable,AutoCloseable
    public classStringWriterextendsWriter
    A character stream that collects its output in a string buffer, which can then be used to construct a string.

    Closing aStringWriter has no effect. The methods in this class can be called after the stream has been closed without generating anIOException.

    Since:
    1.1

    • Constructor Detail

      • 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 ofchar values that will fit into this buffer before it is automatically expanded
        Throws:
        IllegalArgumentException - IfinitialSize is negative

    • Method Detail

      • 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 - Ifoff is negative, orlen is negative, oroff + 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 - Ifoff is negative, orlen is negative, oroff + 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 formout.append(csq) behaves in exactly the same way as the invocation

             out.write(csq.toString())

        Depending on the specification oftoString for the character sequencecsq, the entire sequence may not be appended. For instance, invoking thetoString 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. Ifcsq isnull, 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 formout.append(csq, start, end) whencsq is notnull, 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. Ifcsq isnull, then characters will be appended as ifcsq 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 - Ifstart orend are negative,start is greater thanend, orend is greater thancsq.length()
        Since:
        1.5

      • append

        public StringWriter append​(char c)
        Appends the specified character to this writer.

        An invocation of this method of the formout.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.

      • close

        public void close()           throwsIOException
        Closing aStringWriter has no effect. The methods in this class can be called after the stream has been closed without generating anIOException.
        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