JSONStringer.java

/*
Copyright (c) 2002 JSON.org

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.codehaus.jettison.json;

import java.io.StringWriter;

/**
 * JSONStringer provides a quick and convenient way of producing JSON text.
 * The texts produced strictly conform to JSON syntax rules. No whitespace is
 * added, so the results are ready for transmission or storage. Each instance of
 * JSONStringer can produce one JSON text.
 * <p>
 * A JSONStringer instance provides a <code>value</code> method for appending
 * values to the
 * text, and a <code>key</code>
 * method for adding keys before values in objects. There are <code>array</code>
 * and <code>endArray</code> methods that make and bound array values, and
 * <code>object</code> and <code>endObject</code> methods which make and bound
 * object values. All of these methods return the JSONWriter instance,
 * permitting cascade style. For example, <pre>
 * myString = new JSONStringer()
 *     .object()
 *         .key("JSON")
 *         .value("Hello, World!")
 *     .endObject()
 *     .toString();</pre> which produces the string <pre>
 * {"JSON":"Hello, World!"}</pre>
 * <p>
 * The first method called must be <code>array</code> or <code>object</code>.
 * There are no methods for adding commas or colons. JSONStringer adds them for
 * you. Objects and arrays can be nested up to 20 levels deep.
 * <p>
 * This can sometimes be easier than using a JSONObject to build a string.
 * @author JSON.org
 * @version 2
 */
public class JSONStringer extends JSONWriter {
    /**
     * Make a fresh JSONStringer. It can be used to build one JSON text.
     */
    public JSONStringer() {
        super(new StringWriter());
    }

    /**
     * Return the JSON text. This method is used to obtain the product of the
     * JSONStringer instance. It will return <code>null</code> if there was a
     * problem in the construction of the JSON text (such as the calls to
     * <code>array</code> were not properly balanced with calls to
     * <code>endArray</code>).
     * @return The JSON text.
     */
    public String toString() {
        return this.mode == 'd' ? this.writer.toString() : null;
    }
}