72      */
  73     private void ensureOpen() throws IOException {
  74         if (in == null)
  75             throw new IOException("Stream closed");
  76     }
  77 
  78     /**
  79      * Creates a <code>PushbackInputStream</code>
  80      * with a pushback buffer of the specified <code>size</code>,
  81      * and saves its argument, the input stream
  82      * <code>in</code>, for later use. Initially,
  83      * the pushback buffer is empty.
  84      *
  85      * @param  in    the input stream from which bytes will be read.
  86      * @param  size  the size of the pushback buffer.
  87      * @exception IllegalArgumentException if {@code size <= 0}
  88      * @since  1.1
  89      */
  90     public PushbackInputStream(InputStream in, int size) {
  91         super(in);



  92         if (size <= 0) {
  93             throw new IllegalArgumentException("size <= 0");
  94         }
  95         this.buf = new byte[size];
  96         this.pos = size;
  97     }
  98 
  99     /**
 100      * Creates a <code>PushbackInputStream</code>
 101      * with a 1-byte pushback buffer, and saves its argument, the input stream
 102      * <code>in</code>, for later use. Initially,
 103      * the pushback buffer is empty.
 104      *
 105      * @param   in   the input stream from which bytes will be read.
 106      */
 107     public PushbackInputStream(InputStream in) {
 108         this(in, 1);
 109     }
 110 
 111     /**

  72      */
  73     private void ensureOpen() throws IOException {
  74         if (in == null)
  75             throw new IOException("Stream closed");
  76     }
  77 
  78     /**
  79      * Creates a <code>PushbackInputStream</code>
  80      * with a pushback buffer of the specified <code>size</code>,
  81      * and saves its argument, the input stream
  82      * <code>in</code>, for later use. Initially,
  83      * the pushback buffer is empty.
  84      *
  85      * @param  in    the input stream from which bytes will be read.
  86      * @param  size  the size of the pushback buffer.
  87      * @exception IllegalArgumentException if {@code size <= 0}
  88      * @since  1.1
  89      */
  90     public PushbackInputStream(InputStream in, int size) {
  91         super(in);
  92         if (in == null) {
  93             throw new NullPointerException();
  94         } 
  95         if (size <= 0) {
  96             throw new IllegalArgumentException("size <= 0");
  97         }
  98         this.buf = new byte[size];
  99         this.pos = size;
 100     }
 101 
 102     /**
 103      * Creates a <code>PushbackInputStream</code>
 104      * with a 1-byte pushback buffer, and saves its argument, the input stream
 105      * <code>in</code>, for later use. Initially,
 106      * the pushback buffer is empty.
 107      *
 108      * @param   in   the input stream from which bytes will be read.
 109      */
 110     public PushbackInputStream(InputStream in) {
 111         this(in, 1);
 112     }
 113 
 114     /**