stringvalue.java

jsr170接口的java实现。是个apache的开源项目。

/*
 * 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.
 */
package org.apache.jackrabbit.value;

import javax.jcr.PropertyType;
import javax.jcr.ValueFormatException;

/**
 * A <code>StringValue</code> provides an implementation
 * of the <code>Value</code> interface representing a string value.
 */
public class StringValue extends BaseValue {

    public static final int TYPE = PropertyType.STRING;

    private final String text;

    /**
     * Constructs a <code>StringValue</code> object representing a string.
     *
     * @param text the string this <code>StringValue</code> should represent
     */
    public StringValue(String text) {
        super(TYPE);
        this.text = text;
    }

    /**
     * Indicates whether some other object is "equal to" this one.
     * <p/>
     * The result is <code>true</code> if and only if the argument is not
     * <code>null</code> and is a <code>StringValue</code> object that
     * represents the same value as this object.
     *
     * @param obj the reference object with which to compare.
     * @return <code>true</code> if this object is the same as the obj
     *         argument; <code>false</code> otherwise.
     */
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof StringValue) {
            StringValue other = (StringValue) obj;
            if (text == other.text) {
                return true;
            } else if (text != null && other.text != null) {
                return text.equals(other.text);
            }
        }
        return false;
    }

    /**
     * Returns zero to satisfy the Object equals/hashCode contract.
     * This class is mutable and not meant to be used as a hash key.
     *
     * @return always zero
     * @see Object#hashCode()
     */
    public int hashCode() {
        return 0;
    }

    //------------------------------------------------------------< BaseValue >
    /**
     * {@inheritDoc}
     */
    protected String getInternalString() throws ValueFormatException {
        if (text != null) {
            return text;
        } else {
            throw new ValueFormatException("empty value");
        }
    }
}