46 * @see PipedReader
47 * @see StringReader
48 * @see Writer
49 *
50 * @author Mark Reinhold
51 * @since 1.1
52 */
53
54 public abstract class Reader implements Readable, Closeable {
55
56 private static final int TRANSFER_BUFFER_SIZE = 8192;
57
58 /**
59 * Returns a new {@code Reader} that reads no characters. The returned
60 * stream is initially open. The stream is closed by calling the
61 * {@code close()} method. Subsequent calls to {@code close()} have no
62 * effect.
63 *
64 * <p> While the stream is open, the {@code read()}, {@code read(char[])},
65 * {@code read(char[], int, int)}, {@code read(Charbuffer)}, {@code
66 * ready())}, {@code skip(long)}, and {@code transferTo()} methods all
67 * behave as if end of stream has been reached. After the stream has been
68 * closed, these methods all throw {@code IOException}.
69 *
70 * <p> The {@code markSupported()} method returns {@code false}. The
71 * {@code mark()} method does nothing, and the {@code reset()} method
72 * throws {@code IOException}.
73 *
74 * <p> The {@link #lock object} used to synchronize operations on the
75 * returned {@code Reader} is not specified.
76 *
77 * @return a {@code Reader} which reads no characters
78 *
79 * @since 11
80 */
81 public static Reader nullReader() {
82 return new Reader() {
83 private volatile boolean closed;
84
85 private void ensureOpen() throws IOException {
86 if (closed) {
87 throw new IOException("Stream closed");
88 }
89 }
90
91 @Override
92 public int read() throws IOException {
95 }
96
97 @Override
98 public int read(char[] cbuf, int off, int len) throws IOException {
99 Objects.checkFromIndexSize(off, len, cbuf.length);
100 ensureOpen();
101 if (len == 0) {
102 return 0;
103 }
104 return -1;
105 }
106
107 @Override
108 public int read(CharBuffer target) throws IOException {
109 Objects.requireNonNull(target);
110 ensureOpen();
111 if (target.hasRemaining()) {
112 return -1;
113 }
114 return 0;
115 }
116
117 @Override
118 public long skip(long n) throws IOException {
119 ensureOpen();
120 return 0L;
121 }
122
123 @Override
124 public long transferTo(Writer out) throws IOException {
125 Objects.requireNonNull(out);
126 ensureOpen();
127 return 0L;
128 }
129
130 @Override
131 public void close() {
132 closed = true;
133 }
134 };
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46 * @see PipedReader
47 * @see StringReader
48 * @see Writer
49 *
50 * @author Mark Reinhold
51 * @since 1.1
52 */
53
54 public abstract class Reader implements Readable, Closeable {
55
56 private static final int TRANSFER_BUFFER_SIZE = 8192;
57
58 /**
59 * Returns a new {@code Reader} that reads no characters. The returned
60 * stream is initially open. The stream is closed by calling the
61 * {@code close()} method. Subsequent calls to {@code close()} have no
62 * effect.
63 *
64 * <p> While the stream is open, the {@code read()}, {@code read(char[])},
65 * {@code read(char[], int, int)}, {@code read(Charbuffer)}, {@code
66 * ready()}, {@code skip(long)}, and {@code transferTo()} methods all
67 * behave as if end of stream has been reached. After the stream has been
68 * closed, these methods all throw {@code IOException}.
69 *
70 * <p> The {@code markSupported()} method returns {@code false}. The
71 * {@code mark()} and {@code reset()} methods throw an {@code IOException}.
72 *
73 * <p> The {@link #lock object} used to synchronize operations on the
74 * returned {@code Reader} is not specified.
75 *
76 * @return a {@code Reader} which reads no characters
77 *
78 * @since 11
79 */
80 public static Reader nullReader() {
81 return new Reader() {
82 private volatile boolean closed;
83
84 private void ensureOpen() throws IOException {
85 if (closed) {
86 throw new IOException("Stream closed");
87 }
88 }
89
90 @Override
91 public int read() throws IOException {
94 }
95
96 @Override
97 public int read(char[] cbuf, int off, int len) throws IOException {
98 Objects.checkFromIndexSize(off, len, cbuf.length);
99 ensureOpen();
100 if (len == 0) {
101 return 0;
102 }
103 return -1;
104 }
105
106 @Override
107 public int read(CharBuffer target) throws IOException {
108 Objects.requireNonNull(target);
109 ensureOpen();
110 if (target.hasRemaining()) {
111 return -1;
112 }
113 return 0;
114 }
115
116 @Override
117 public boolean ready() throws IOException {
118 ensureOpen();
119 return false;
120 }
121
122 @Override
123 public long skip(long n) throws IOException {
124 ensureOpen();
125 return 0L;
126 }
127
128 @Override
129 public long transferTo(Writer out) throws IOException {
130 Objects.requireNonNull(out);
131 ensureOpen();
132 return 0L;
133 }
134
135 @Override
136 public void close() {
137 closed = true;
138 }
139 };
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