changeset 49727:1b3ee04e3e54

8196298: Add null Reader and Writer Reviewed-by: bpb, forax, smarks, alanb, rriggs Contributed-by: patrick@reini.net
author rriggs
date Mon, 19 Mar 2018 09:58:41 -0400
parents d5c43e9f08fb
children 78af880eec61
files src/java.base/share/classes/java/io/Reader.java src/java.base/share/classes/java/io/Writer.java test/jdk/java/io/Reader/NullReader.java test/jdk/java/io/Writer/NullWriter.java
diffstat 4 files changed, 476 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/src/java.base/share/classes/java/io/Reader.java	Fri Mar 16 21:40:09 2018 +0100
+++ b/src/java.base/share/classes/java/io/Reader.java	Mon Mar 19 09:58:41 2018 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,7 @@
 package java.io;
 
 
+import java.nio.CharBuffer;
 import java.util.Objects;
 
 /**
@@ -55,6 +56,85 @@
     private static final int TRANSFER_BUFFER_SIZE = 8192;
 
     /**
+     * Returns a new {@code Reader} that reads no characters. The returned
+     * stream is initially open.  The stream is closed by calling the
+     * {@code close()} method.  Subsequent calls to {@code close()} have no
+     * effect.
+     *
+     * <p> While the stream is open, the {@code read()}, {@code read(char[])},
+     * {@code read(char[], int, int)}, {@code read(Charbuffer)}, {@code
+     * ready())}, {@code skip(long)}, and {@code transferTo()} methods all
+     * behave as if end of stream has been reached.  After the stream has been
+     * closed, these methods all throw {@code IOException}.
+     *
+     * <p> The {@code markSupported()} method returns {@code false}.  The
+     * {@code mark()} method does nothing, and the {@code reset()} method
+     * throws {@code IOException}.
+     *
+     * <p> The {@link #lock object} used to synchronize operations on the
+     * returned {@code Reader} is not specified.
+     *
+     * @return a {@code Reader} which reads no characters
+     *
+     * @since 11
+     */
+    public static Reader nullReader() {
+        return new Reader() {
+            private volatile boolean closed;
+
+            private void ensureOpen() throws IOException {
+                if (closed) {
+                    throw new IOException("Stream closed");
+                }
+            }
+
+            @Override
+            public int read() throws IOException {
+                ensureOpen();
+                return -1;
+            }
+
+            @Override
+            public int read(char[] cbuf, int off, int len) throws IOException {
+                Objects.checkFromIndexSize(off, len, cbuf.length);
+                ensureOpen();
+                if (len == 0) {
+                    return 0;
+                }
+                return -1;
+            }
+
+            @Override
+            public int read(CharBuffer target) throws IOException {
+                Objects.requireNonNull(target);
+                ensureOpen();
+                if (target.hasRemaining()) {
+                    return -1;
+                }
+                return 0;
+            }
+
+            @Override
+            public long skip(long n) throws IOException {
+                ensureOpen();
+                return 0L;
+            }
+
+            @Override
+            public long transferTo(Writer out) throws IOException {
+                Objects.requireNonNull(out);
+                ensureOpen();
+                return 0L;
+            }
+
+            @Override
+            public void close() {
+                closed = true;
+            }
+        };
+    }
+
+    /**
      * The object used to synchronize operations on this stream.  For
      * efficiency, a character-stream object may use an object other than
      * itself to protect critical sections.  A subclass should therefore use
--- a/src/java.base/share/classes/java/io/Writer.java	Fri Mar 16 21:40:09 2018 +0100
+++ b/src/java.base/share/classes/java/io/Writer.java	Mon Mar 19 09:58:41 2018 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,8 @@
 package java.io;
 
 
+import java.util.Objects;
+
 /**
  * Abstract class for writing to character streams.  The only methods that a
  * subclass must implement are write(char[], int, int), flush(), and close().
@@ -59,6 +61,91 @@
     private static final int WRITE_BUFFER_SIZE = 1024;
 
     /**
+     * Returns a new {@code Writer} which discards all characters.  The
+     * returned stream is initially open.  The stream is closed by calling
+     * the {@code close()} method.  Subsequent calls to {@code close()} have
+     * no effect.
+     *
+     * <p> While the stream is open, the {@code append(char)}, {@code
+     * append(CharSequence)}, {@code append(CharSequence, int, int)},
+     * {@code flush()}, {@code write(int)}, {@code write(char[])}, and
+     * {@code write(char[], int, int)} methods do nothing. After the stream
+     * has been closed, these methods all throw {@code IOException}.
+     *
+     * <p> The {@link #lock object} used to synchronize operations on the
+     * returned {@code Writer} is not specified.
+     *
+     * @return a {@code Writer} which discards all characters
+     *
+     * @since 11
+     */
+    public static Writer nullWriter() {
+        return new Writer() {
+            private volatile boolean closed;
+
+            private void ensureOpen() throws IOException {
+                if (closed) {
+                    throw new IOException("Stream closed");
+                }
+            }
+
+            @Override
+            public Writer append(char c) throws IOException {
+                ensureOpen();
+                return this;
+            }
+
+            @Override
+            public Writer append(CharSequence csq) throws IOException {
+                ensureOpen();
+                return this;
+            }
+
+            @Override
+            public Writer append(CharSequence csq, int start, int end) throws IOException {
+                ensureOpen();
+                if (csq != null) {
+                    Objects.checkFromToIndex(start, end, csq.length());
+                }
+                return this;
+            }
+
+            @Override
+            public void write(int c) throws IOException {
+                ensureOpen();
+            }
+
+            @Override
+            public void write(char[] cbuf, int off, int len) throws IOException {
+                Objects.checkFromIndexSize(off, len, cbuf.length);
+                ensureOpen();
+            }
+
+            @Override
+            public void write(String str) throws IOException {
+                Objects.requireNonNull(str);
+                ensureOpen();
+            }
+
+            @Override
+            public void write(String str, int off, int len) throws IOException {
+                Objects.checkFromIndexSize(off, len, str.length());
+                ensureOpen();
+            }
+
+            @Override
+            public void flush() throws IOException {
+                ensureOpen();
+            }
+
+            @Override
+            public void close() throws IOException {
+                closed = true;
+            }
+        };
+    }
+
+    /**
      * The object used to synchronize operations on this stream.  For
      * efficiency, a character-stream object may use an object other than
      * itself to protect critical sections.  A subclass should therefore use
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/io/Reader/NullReader.java	Mon Mar 19 09:58:41 2018 -0400
@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.io.Reader;
+import java.io.IOException;
+import java.io.StringWriter;
+import java.nio.CharBuffer;
+import java.nio.ReadOnlyBufferException;
+
+import org.testng.annotations.AfterGroups;
+import org.testng.annotations.BeforeGroups;
+import org.testng.annotations.Test;
+
+import static org.testng.Assert.*;
+
+/*
+ * @test
+ * @bug 8196298
+ * @run testng NullReader
+ * @summary Check for expected behavior of Reader.nullReader().
+ */
+public class NullReader {
+    private static Reader openReader;
+    private static Reader closedReader;
+
+    @BeforeGroups(groups = "open")
+    public static void openStream() {
+        openReader = Reader.nullReader();
+    }
+
+    @BeforeGroups(groups = "closed")
+    public static void openAndCloseStream() throws IOException {
+        closedReader = Reader.nullReader();
+        closedReader.close();
+    }
+
+    @AfterGroups(groups = "open")
+    public static void closeStream() throws IOException {
+        openReader.close();
+    }
+
+    @Test(groups = "open")
+    public static void testOpen() {
+        assertNotNull(openReader, "Reader.nullReader() returned null");
+    }
+
+    @Test(groups = "open")
+    public static void testRead() throws IOException {
+        assertEquals(-1, openReader.read(), "read() != -1");
+    }
+
+    @Test(groups = "open")
+    public static void testReadBII() throws IOException {
+        assertEquals(-1, openReader.read(new char[1], 0, 1),
+                "read(char[],int,int) != -1");
+    }
+
+    @Test(groups = "open")
+    public static void testReadBIILenZero() throws IOException {
+        assertEquals(0, openReader.read(new char[1], 0, 0),
+                "read(char[],int,int) != 0");
+    }
+
+    @Test(groups = "open")
+    public static void testReadCharBuffer() throws IOException {
+        CharBuffer charBuffer = CharBuffer.allocate(1);
+        assertEquals(-1, openReader.read(charBuffer),
+                "read(CharBuffer) != -1");
+    }
+
+    @Test(groups = "open")
+    public static void testReadCharBufferZeroRemaining() throws IOException {
+        CharBuffer charBuffer = CharBuffer.allocate(0);
+        assertEquals(0, openReader.read(charBuffer),
+                "read(CharBuffer) != 0");
+    }
+
+    @Test(groups = "open")
+    public static void testSkip() throws IOException {
+        assertEquals(0, openReader.skip(1), "skip() != 0");
+    }
+
+    @Test(groups = "open")
+    public static void testTransferTo() throws IOException {
+        assertEquals(0, openReader.transferTo(new StringWriter(7)),
+                "transferTo() != 0");
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testReadClosed() throws IOException {
+        closedReader.read();
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testReadBIIClosed() throws IOException {
+        closedReader.read(new char[1], 0, 1);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testReadCharBufferClosed() throws IOException {
+        CharBuffer charBuffer = CharBuffer.allocate(0);
+        closedReader.read(charBuffer);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testReadCharBufferZeroRemainingClosed() throws IOException {
+        CharBuffer charBuffer = CharBuffer.allocate(0);
+        closedReader.read(charBuffer);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testSkipClosed() throws IOException {
+        closedReader.skip(1);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testTransferToClosed() throws IOException {
+        closedReader.transferTo(new StringWriter(7));
+    }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/io/Writer/NullWriter.java	Mon Mar 19 09:58:41 2018 -0400
@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.io.IOException;
+import java.io.Writer;
+
+import org.testng.annotations.AfterGroups;
+import org.testng.annotations.BeforeGroups;
+import org.testng.annotations.Test;
+
+import static org.testng.Assert.*;
+
+/*
+ * @test
+ * @bug 8196298
+ * @run testng NullWriter
+ * @summary Check for expected behavior of Writer.nullWriter().
+ */
+public class NullWriter {
+    private static Writer openWriter;
+    private static Writer closedWriter;
+
+    @BeforeGroups(groups = "open")
+    public static void openStream() {
+        openWriter = Writer.nullWriter();
+    }
+
+    @BeforeGroups(groups = "closed")
+    public static void openAndCloseStream() throws IOException {
+        closedWriter = Writer.nullWriter();
+        closedWriter.close();
+    }
+
+    @AfterGroups(groups = "open")
+    public static void closeStream() throws IOException {
+        openWriter.close();
+    }
+
+    @Test(groups = "open")
+    public static void testOpen() {
+        assertNotNull(openWriter, "Writer.nullWriter() returned null");
+    }
+
+    @Test(groups = "open")
+    public static void testAppendChar() throws IOException {
+        assertSame(openWriter, openWriter.append('x'));
+    }
+
+    @Test(groups = "open")
+    public static void testAppendCharSequence() throws IOException {
+        CharSequence cs = "abc";
+        assertSame(openWriter, openWriter.append(cs));
+    }
+
+    @Test(groups = "open")
+    public static void testAppendCharSequenceNull() throws IOException {
+        assertSame(openWriter, openWriter.append(null));
+    }
+
+    @Test(groups = "open")
+    public static void testAppendCharSequenceII() throws IOException {
+        CharSequence cs = "abc";
+        assertSame(openWriter, openWriter.append(cs, 0, 1));
+    }
+
+    @Test(groups = "open")
+    public static void testAppendCharSequenceIINull() throws IOException {
+        assertSame(openWriter, openWriter.append(null, 2, 1));
+    }
+
+    @Test(groups = "open")
+    public static void testFlush() throws IOException {
+        openWriter.flush();
+    }
+
+    @Test(groups = "open")
+    public static void testWrite() throws IOException {
+        openWriter.write(62832);
+    }
+
+    @Test(groups = "open")
+    public static void testWriteString() throws IOException {
+        openWriter.write("");
+    }
+
+    @Test(groups = "open")
+    public static void testWriteStringII() throws IOException {
+        openWriter.write("", 0, 0);
+    }
+
+    @Test(groups = "open")
+    public static void testWriteBII() throws IOException, Exception {
+        openWriter.write(new char[]{(char) 6}, 0, 1);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testAppendCharClosed() throws IOException {
+        closedWriter.append('x');
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testAppendCharSequenceClosed() throws IOException {
+        CharSequence cs = "abc";
+        closedWriter.append(cs);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testAppendCharSequenceNullClosed() throws IOException {
+        closedWriter.append(null);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testAppendCharSequenceIIClosed() throws IOException {
+        CharSequence cs = "abc";
+        closedWriter.append(cs, 0, 1);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testAppendCharSequenceIINullClosed() throws IOException {
+        closedWriter.append(null, 2, 1);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testFlushClosed() throws IOException {
+        closedWriter.flush();
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testWriteClosed() throws IOException {
+        closedWriter.write(62832);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testWriteStringClosed() throws IOException {
+        closedWriter.write("");
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testWriteStringIIClosed() throws IOException {
+        closedWriter.write("", 0, 0);
+    }
+
+    @Test(groups = "closed", expectedExceptions = IOException.class)
+    public static void testWriteBIIClosed() throws IOException {
+        closedWriter.write(new char[]{(char) 6}, 0, 1);
+    }
+}