An assertion utility just for simple checks. : Assert « Language Basics « Java

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2. Language Basics
3. Assert

An assertion utility just for simple checks.

        
/*
 * Copyright 2008-2009 the T2 Project ant the Others.
 *
 * 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 org.t2framework.commons.util;

/**
 * An assertion utility just for simple checks.
 * 
 * @author shot
 */
public class Assertion {

  /**
   * Assert whether the target is not null.If null, throw
   * {@link NullPointerException}.
   * 
   * @param <T>
   * @param target
   * @return
   */
  public static <T> T notNull(T target) {
    return notNull(target, null);
  }

  /**
   * Assert whether the target is not null with the message. If null, throw
   * {@link NullPointerException}.
   * 
   * @param <T>
   * @param target
   * @param message
   * @return
   */
  public static <T> T notNull(T target, String message) {
    if (target == null) {
      throw new NullPointerException(message);
    }
    return target;
  }

  /**
   * Assert if the arguments are not null. If null, throw
   * {@link NullPointerException}.
   * 
   * @param <T>
   * @param args
   * @return
   */
  public static <T> T[] notNulls(T... args) {
    notNull(args);
    for (int i = 0; i < args.length; i++) {
      notNull(args[i]);
    }
    return args;
  }

  /**
   * Assert if the target is not null.This method returns true/false instead
   * of exception.
   * 
   * @param <T>
   * @param t
   * @return
   */
  public static <T> boolean isNotNull(T t) {
    return (t != null);
  }

  /**
   * Assert if the target argument is not null.This method returns true/false
   * instead of exception.
   * 
   * @param <T>
   * @param args
   * @return
   */
  public static <T> boolean hasNotNull(T... args) {
    return !hasNull(args);
  }

  /**
   * Assert if the target is null.This method returns true/false instead of
   * exception.
   * 
   * @param <T>
   * @param t
   * @return
   */
  public static <T> boolean isNull(T t) {
    return (t == null);
  }

  /**
   * Assert if the argument contains null.This method returns true/false
   * instead of exception.
   * 
   * @param <T>
   * @param args
   * @return
   */
  public static <T> boolean hasNull(T... args) {
    notNull(args);
    for (T t : args) {
      if (t == null) {
        return true;
      }
    }
    return false;
  }

  /**
   * Assert if the target argument is all null.
   * 
   * @param <T>
   * @param args
   * @return
   */
  public static <T> boolean isAllNull(T... args) {
    notNull(args);
    for (T t : args) {
      if (t != null) {
        return false;
      }
    }
    return true;
  }

  public static void positive(int i) {
    if (i < 0) {
      throw new IllegalArgumentException();
    }
  }
}
---------------
/*
 * Copyright 2008-2009 the T2 Project ant the Others.
 *
 * 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 org.t2framework.commons.util;

import org.t2framework.commons.util.Assertion;

import junit.framework.TestCase;

/**
 * @author shot
 */
public class AssertionTest extends TestCase {

  public void testNotNull() throws Exception {
    try {
      Assertion.notNull(null);
      fail();
    } catch (NullPointerException e) {
    }
  }

  public void testNotNull2() throws Exception {
    try {
      String s = Assertion.notNull("hoge");
      assertEquals("hoge", s);
    } catch (NullPointerException expected) {
      fail();
    }
  }

  public void testNotNulls() throws Exception {
    try {
      Assertion.notNulls("hoge", "fuga", null);
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testNotNulls2() throws Exception {
    try {
      String s = null;
      Assertion.notNulls(s);
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testNotNulls3() throws Exception {
    try {
      Assertion.notNulls(1, 2, 3);
    } catch (NullPointerException e) {
      fail();
    }
  }

  public void testIsNull1() throws Exception {
    assertTrue(Assertion.isNull(null));
    assertFalse(Assertion.isNull(""));
  }

  public void testHasNull1() throws Exception {
    assertTrue(Assertion.hasNull("a", null, "b"));
    assertTrue(Assertion.hasNull(null, "b"));
    assertTrue(Assertion.hasNull(null, null, null));
    assertTrue(Assertion.hasNull("a", null, null));
    assertFalse(Assertion.hasNull("a", "b", "c"));
  }
}

   
    
    
    
    
    
    
    
  

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