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Java example source code file (MapMakerTest.java)

This example Java source code file (MapMakerTest.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

concurrentmap, countdownlatch, delayingidentityloader, function, gwtincompatible, illegalargumentexception, mapmaker, nullpointertester, object, override, runtimeexception, string, suppresswarnings, testcase, threading, threads, util

The MapMakerTest.java Java example source code

/*
 * Copyright (C) 2011 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.collect;

import static com.google.common.util.concurrent.Uninterruptibles.awaitUninterruptibly;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Function;
import com.google.common.testing.NullPointerTester;

import junit.framework.TestCase;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CountDownLatch;

/**
 * @author Charles Fry
 */
@GwtCompatible(emulated = true)
public class MapMakerTest extends TestCase {

  @GwtIncompatible // NullPointerTester
  public void testNullParameters() throws Exception {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicInstanceMethods(new MapMaker());
  }

  @GwtIncompatible // threads

  public void testRemovalNotification_clear() throws InterruptedException {
    // If a clear() happens while a computation is pending, we should not get a removal
    // notification.

    final CountDownLatch computingLatch = new CountDownLatch(1);
    Function<String, String> computingFunction = new DelayingIdentityLoader(computingLatch);

    @SuppressWarnings("deprecation") // test of deprecated code
    final ConcurrentMap<String, String> map = new MapMaker()
        .concurrencyLevel(1)
        .makeComputingMap(computingFunction);

    // seed the map, so its segment's count > 0
    map.put("a", "a");

    final CountDownLatch computationStarted = new CountDownLatch(1);
    final CountDownLatch computationComplete = new CountDownLatch(1);
    new Thread(new Runnable() {
      @Override public void run() {
        computationStarted.countDown();
        map.get("b");
        computationComplete.countDown();
      }
    }).start();

    // wait for the computingEntry to be created
    computationStarted.await();
    map.clear();
    // let the computation proceed
    computingLatch.countDown();
    // don't check map.size() until we know the get("b") call is complete
    computationComplete.await();

    assertEquals(1, map.size());
    assertEquals("b", map.get("b"));
  }

  @GwtIncompatible // threads
  static final class DelayingIdentityLoader<T> implements Function {
    private final CountDownLatch delayLatch;

    DelayingIdentityLoader(CountDownLatch delayLatch) {
      this.delayLatch = delayLatch;
    }

    @Override public T apply(T key) {
      awaitUninterruptibly(delayLatch);
      return key;
    }
  }

  /*
   * TODO(cpovirk): eliminate duplication between these tests and those in LegacyMapMakerTests and
   * anywhere else
   */

  /** Tests for the builder. */
  public static class MakerTest extends TestCase {
    public void testInitialCapacity_negative() {
      MapMaker maker = new MapMaker();
      try {
        maker.initialCapacity(-1);
        fail();
      } catch (IllegalArgumentException expected) {
      }
    }

    // TODO(cpovirk): enable when ready
    public void xtestInitialCapacity_setTwice() {
      MapMaker maker = new MapMaker().initialCapacity(16);
      try {
        // even to the same value is not allowed
        maker.initialCapacity(16);
        fail();
      } catch (IllegalArgumentException expected) {
      }
    }

    public void testReturnsPlainConcurrentHashMapWhenPossible() {
      Map<?, ?> map = new MapMaker()
          .initialCapacity(5)
          .makeMap();
      assertTrue(map instanceof ConcurrentHashMap);
    }
  }

  /** Tests for recursive computation. */
  public static class RecursiveComputationTest extends TestCase {
    Function<Integer, String> recursiveComputer
        = new Function<Integer, String>() {
      @Override
      public String apply(Integer key) {
        if (key > 0) {
          return key + ", " + recursiveMap.get(key - 1);
        } else {
          return "0";
        }
      }
    };

    ConcurrentMap<Integer, String> recursiveMap = new MapMaker()
        .makeComputingMap(recursiveComputer);

    public void testRecursiveComputation() {
      assertEquals("3, 2, 1, 0", recursiveMap.get(3));
    }
  }

  /**
   * Tests for computing functionality.
   */
  public static class ComputingTest extends TestCase {
    public void testComputerThatReturnsNull() {
      ConcurrentMap<Integer, String> map = new MapMaker()
          .makeComputingMap(new Function<Integer, String>() {
            @Override
            public String apply(Integer key) {
              return null;
            }
          });
      try {
        map.get(1);
        fail();
      } catch (NullPointerException e) { /* expected */ }
    }

    public void testRuntimeException() {
      final RuntimeException e = new RuntimeException();

      ConcurrentMap<Object, Object> map = new MapMaker().makeComputingMap(
          new Function<Object, Object>() {
        @Override
        public Object apply(Object from) {
          throw e;
        }
      });

      try {
        map.get(new Object());
        fail();
      } catch (ComputationException ce) {
        assertSame(e, ce.getCause());
      }
    }
  }
}

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