android_translation_layer/src/api-impl/android/util/Property.java

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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 android.util;

/**
 * A property is an abstraction that can be used to represent a <emb>mutable</em> value that is held
 * in a <em>host</em> object. The Property's {@link #set(Object, Object)} or {@link #get(Object)}
 * methods can be implemented in terms of the private fields of the host object, or via "setter" and
 * "getter" methods or by some other mechanism, as appropriate.
 *
 * @param <T> The class on which the property is declared.
 * @param <V> The type that this property represents.
 */
public abstract class Property<T, V> {
	private final String mName;
	private final Class<V> mType;

	/**
	 * A constructor that takes an identifying name and {@link #getType() type} for the property.
	 */
	public Property(Class<V> type, String name) {
		mName = name;
		mType = type;
	}

	/**
	 * Returns true if the {@link #set(Object, Object)} method does not set the value on the target
	 * object (in which case the {@link #set(Object, Object) set()} method should throw a {@link
	 * NoSuchPropertyException} exception). This may happen if the Property wraps functionality that
	 * allows querying the underlying value but not setting it. For example, the {@link #of(Class,
	 * Class, String)} factory method may return a Property with name "foo" for an object that has
	 * only a <code>getFoo()</code> or <code>isFoo()</code> method, but no matching
	 * <code>setFoo()</code> method.
	 */
	public boolean isReadOnly() {
		return false;
	}

	/**
	 * Sets the value on <code>object</code> which this property represents. If the method is unable
	 * to set the value on the target object it will throw an {@link UnsupportedOperationException}
	 * exception.
	 */
	public void set(T object, V value) {
		throw new UnsupportedOperationException("Property " + getName() +" is read-only");
	}

	/**
	 * Returns the current value that this property represents on the given <code>object</code>.
	 */
	public abstract V get(T object);

	/**
	 * Returns the name for this property.
	 */
	public String getName() {
		return mName;
	}

	/**
	 * Returns the type for this property.
	 */
	public Class<V> getType() {
		return mType;
	}
}