Module java.base
Package java.io

Class StringReader

java.lang.Object
java.io.Reader
java.io.StringReader
All Implemented Interfaces:
Closeable, AutoCloseable, Readable

public class StringReader extends Reader
A character stream whose source is a string.
Since:
1.1
  • Field Summary

    Fields declared in class java.io.Reader

    lock
  • Constructor Summary

    Constructors
    Constructor
    Description
    Creates a new string reader.
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    Closes the stream and releases any system resources associated with it.
    void
    mark​(int readAheadLimit)
    Marks the present position in the stream.
    boolean
    Tells whether this stream supports the mark() operation, which it does.
    int
    Reads a single character.
    int
    read​(char[] cbuf, int off, int len)
    Reads characters into a portion of an array.
    boolean
    Tells whether this stream is ready to be read.
    void
    Resets the stream to the most recent mark, or to the beginning of the string if it has never been marked.
    long
    skip​(long n)
    Skips characters.

    Methods declared in class java.io.Reader

    nullReader, read, read, transferTo

    Methods declared in class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • StringReader

      public StringReader(String s)
      Creates a new string reader.
      Parameters:
      s - String providing the character stream.
  • Method Details

    • read

      public int read() throws IOException
      Reads a single character.
      Overrides:
      read in class Reader
      Returns:
      The character read, or -1 if the end of the stream has been reached
      Throws:
      IOException - If an I/O error occurs
    • read

      public int read(char[] cbuf, int off, int len) throws IOException
      Reads characters into a portion of an array.

      If len is zero, then no characters are read and 0 is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value -1 is returned; otherwise, at least one character is read and stored into cbuf.

      Specified by:
      read in class Reader
      Parameters:
      cbuf - Destination buffer
      off - Offset at which to start storing characters
      len - Maximum number of characters to read
      Returns:
      The number of characters read, or -1 if the end of the stream has been reached
      Throws:
      IndexOutOfBoundsException - If off is negative, or len is negative, or len is greater than cbuf.length - off
      IOException - If an I/O error occurs
    • skip

      public long skip(long n) throws IOException
      Skips characters. If the stream is already at its end before this method is invoked, then no characters are skipped and zero is returned.

      The n parameter may be negative, even though the skip method of the Reader superclass throws an exception in this case. Negative values of n cause the stream to skip backwards. Negative return values indicate a skip backwards. It is not possible to skip backwards past the beginning of the string.

      If the entire string has been read or skipped, then this method has no effect and always returns 0.

      Overrides:
      skip in class Reader
      Parameters:
      n - The number of characters to skip
      Returns:
      The number of characters actually skipped
      Throws:
      IOException - If an I/O error occurs
    • ready

      public boolean ready() throws IOException
      Tells whether this stream is ready to be read.
      Overrides:
      ready in class Reader
      Returns:
      True if the next read() is guaranteed not to block for input
      Throws:
      IOException - If the stream is closed
    • markSupported

      public boolean markSupported()
      Tells whether this stream supports the mark() operation, which it does.
      Overrides:
      markSupported in class Reader
      Returns:
      true if and only if this stream supports the mark operation.
    • mark

      public void mark(int readAheadLimit) throws IOException
      Marks the present position in the stream. Subsequent calls to reset() will reposition the stream to this point.
      Overrides:
      mark in class Reader
      Parameters:
      readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. Because the stream's input comes from a string, there is no actual limit, so this argument must not be negative, but is otherwise ignored.
      Throws:
      IllegalArgumentException - If readAheadLimit < 0
      IOException - If an I/O error occurs
    • reset

      public void reset() throws IOException
      Resets the stream to the most recent mark, or to the beginning of the string if it has never been marked.
      Overrides:
      reset in class Reader
      Throws:
      IOException - If an I/O error occurs
    • close

      public void close()
      Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), ready(), mark(), or reset() invocations will throw an IOException. Closing a previously closed stream has no effect. This method will block while there is another thread blocking on the reader.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Specified by:
      close in class Reader