Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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. */ import java.io.Serializable; /** * A mutable <code>boolean</code> wrapper. * * @see Boolean * @since 2.2 * @author Apache Software Foundation * @version $Id: MutableBoolean.java 491052 2006-12-29 17:16:37Z scolebourne $ */ public class MutableBoolean implements Mutable, Serializable, Comparable { /** * Required for serialization support. * * @see java.io.Serializable */ private static final long serialVersionUID = -4830728138360036487L; /** The mutable value. */ private boolean value; /** * Constructs a new MutableBoolean with the default value of false. */ public MutableBoolean() { super(); } /** * Constructs a new MutableBoolean with the specified value. * * @param value * a value. */ public MutableBoolean(boolean value) { super(); this.value = value; } /** * Constructs a new MutableBoolean with the specified value. * * @param value * a value. * @throws NullPointerException * if the object is null */ public MutableBoolean(Boolean value) { super(); this.value = value.booleanValue(); } // ----------------------------------------------------------------------- /** * Returns the value of this MutableBoolean as a boolean. * * @return the boolean value represented by this object. */ public boolean booleanValue() { return value; } /** * Compares this mutable to another in ascending order. * * @param obj * the mutable to compare to * @return zero if this object represents the same boolean value as the argument; a positive value if this object * represents true and the argument represents false; and a negative value if this object represents false * and the argument represents true * @throws ClassCastException * if the argument is not a MutableInt */ public int compareTo(Object obj) { MutableBoolean other = (MutableBoolean) obj; boolean anotherVal = other.value; return value == anotherVal ? 0 : (value ? 1 : -1); } // ----------------------------------------------------------------------- /** * Compares this object to the specified object. The result is <code>true</code> if and only if the argument is * not <code>null</code> and is an <code>MutableBoolean</code> object that contains the same * <code>boolean</code> value as this object. * * @param obj * the object to compare with. * @return <code>true</code> if the objects are the same; <code>false</code> otherwise. */ public boolean equals(Object obj) { if (obj instanceof MutableBoolean) { return value == ((MutableBoolean) obj).booleanValue(); } return false; } // ----------------------------------------------------------------------- /** * Gets the value as a Boolean instance. * * @return the value as a Boolean */ public Object getValue() { return this.value; } /** * Returns a suitable hashcode for this mutable. * * @return the integer <code>1231</code> if this object represents <code>true</code>; returns the integer * <code>1237</code> if this object represents <code>false</code>. */ public int hashCode() { return value ? Boolean.TRUE.hashCode() : Boolean.FALSE.hashCode(); } /** * Sets the value. * * @param value * the value to set */ public void setValue(boolean value) { this.value = value; } /** * Sets the value from any Boolean instance. * * @param value * the value to set * @throws NullPointerException * if the object is null * @throws ClassCastException * if the type is not a {@link Boolean} */ public void setValue(Object value) { setValue(((Boolean) value).booleanValue()); } /** * Returns the String value of this mutable. * * @return the mutable value as a string */ public String toString() { return String.valueOf(value); } } /* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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. */ /** * Provides mutable access to a value. * <p> * <code>Mutable</code> is used as a generic interface to the implementations in this package. * <p> * A typical use case would be to enable a primitive or string to be passed to a method and allow that method to * effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in * a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects. * * @author Matthew Hawthorne * @since 2.1 * @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $ */ interface Mutable { /** * Gets the value of this mutable. * * @return the stored value */ Object getValue(); /** * Sets the value of this mutable. * * @param value * the value to store * @throws NullPointerException * if the object is null and null is invalid * @throws ClassCastException * if the type is invalid */ void setValue(Object value); }