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Java example source code file (MultiReaderTest.java)

This example Java source code file (MultiReaderTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

charsource, exception, illegalstateexception, ioexception, iterable, more, multireadertest, override, reader, string, stringreader, testcase

The MultiReaderTest.java Java example source code

/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.io;

import com.google.common.collect.ImmutableList;

import junit.framework.TestCase;

import java.io.FilterReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

/**
 * @author ricebin
 */
public class MultiReaderTest extends TestCase {

  public void testOnlyOneOpen() throws Exception {
    String testString = "abcdefgh";
    final CharSource source = newCharSource(testString);
    final int[] counter = new int[1];
    CharSource reader = new CharSource() {
      @Override
      public Reader openStream() throws IOException {
        if (counter[0]++ != 0) {
          throw new IllegalStateException("More than one source open");
        }
        return new FilterReader(source.openStream()) {
          @Override public void close() throws IOException {
            super.close();
            counter[0]--;
          }
        };
      }
    };
    Reader joinedReader = CharSource.concat(reader, reader, reader).openStream();
    String result = CharStreams.toString(joinedReader);
    assertEquals(testString.length() * 3, result.length());
  }

  public void testReady() throws Exception {
    CharSource source = newCharSource("a");
    Iterable<? extends CharSource> list = ImmutableList.of(source, source);
    Reader joinedReader = CharSource.concat(list).openStream();

    assertTrue(joinedReader.ready());
    assertEquals('a', joinedReader.read());
    assertEquals('a', joinedReader.read());
    assertEquals(-1, joinedReader.read());
    assertFalse(joinedReader.ready());
  }

  public void testSimple() throws Exception {
    String testString = "abcdefgh";
    CharSource source = newCharSource(testString);
    Reader joinedReader = CharSource.concat(source, source).openStream();

    String expectedString = testString + testString;
    assertEquals(expectedString, CharStreams.toString(joinedReader));
  }

  private static CharSource newCharSource(final String text) {
    return new CharSource() {
      @Override
      public Reader openStream() {
        return new StringReader(text);
      }
    };
  }

  public void testSkip() throws Exception {
    String begin = "abcde";
    String end = "fghij";
    Reader joinedReader =
        CharSource.concat(newCharSource(begin), newCharSource(end)).openStream();

    String expected = begin + end;
    assertEquals(expected.charAt(0), joinedReader.read());
    CharStreams.skipFully(joinedReader, 1);
    assertEquals(expected.charAt(2), joinedReader.read());
    CharStreams.skipFully(joinedReader, 4);
    assertEquals(expected.charAt(7), joinedReader.read());
    CharStreams.skipFully(joinedReader, 1);
    assertEquals(expected.charAt(9), joinedReader.read());
    assertEquals(-1, joinedReader.read());
  }

  public void testSkipZero() throws Exception {
    CharSource source = newCharSource("a");
    Iterable<CharSource> list = ImmutableList.of(source, source);
    Reader joinedReader = CharSource.concat(list).openStream();

    assertEquals(0, joinedReader.skip(0));
    assertEquals('a', joinedReader.read());
  }

}

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