Ant example source code file (ConditionTask.java)

This example Ant source code file (ConditionTask.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

buildexception, buildexception, condition, condition, conditionbase, conditiontask, conditiontask, string, string, the, you

The ConditionTask.java source code

/*
 *  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.tools.ant.taskdefs;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.taskdefs.condition.Condition;
import org.apache.tools.ant.taskdefs.condition.ConditionBase;

/**
 * Task to set a property conditionally using <uptodate>, <available>,
 * and many other supported conditions.
 *
 * <p>This task supports boolean logic as well as pluggable conditions
 * to decide, whether a property should be set.</p>
 *
 * <p>This task does not extend Task to take advantage of
 * ConditionBase.</p>
 *
 * @since Ant 1.4
 *
 * @ant.task category="control"
 */
public class ConditionTask extends ConditionBase {

    private String property = null;
    private String value = "true";
    private String alternative = null;

    /**
     * Constructor, names this task "condition".
     */
    public ConditionTask() {
        super("condition");
    }

    /**
     * The name of the property to set. Required.
     * @param p the name of the property
     * @since Ant 1.4
     */
    public void setProperty(String p) {
        property = p;
    }

    /**
     * The value for the property to set, if condition evaluates to true.
     * Defaults to "true".
     * @param v the value of the property
     * @since Ant 1.4
     */
    public void setValue(String v) {
        value = v;
    }

    /**
     * The value for the property to set, if condition evaluates to false.
     * If this attribute is not specified, the property will not be set.
     * @param e the alternate value of the property.
     * @since Ant 1.6.3
     */
    public void setElse(String e) {
        alternative = e;
    }

    /**
     * See whether our nested condition holds and set the property.
     *
     * @since Ant 1.4
     * @exception BuildException if an error occurs
     */
    public void execute() throws BuildException {
        if (countConditions() > 1) {
            throw new BuildException("You must not nest more than one "
                + "condition into <"
                + getTaskName() + ">");
        }
        if (countConditions() < 1) {
            throw new BuildException("You must nest a condition into <"
                + getTaskName() + ">");
        }
        if (property == null) {
            throw new BuildException("The property attribute is required.");
        }
        Condition c = (Condition) getConditions().nextElement();
        if (c.eval()) {
            log("Condition true; setting " + property + " to " + value,
                Project.MSG_DEBUG);
            getProject().setNewProperty(property, value);
        } else if (alternative != null) {
            log("Condition false; setting " + property + " to " + alternative,
                Project.MSG_DEBUG);
            getProject().setNewProperty(property, alternative);
        } else {
            log("Condition false; not setting " + property,
                Project.MSG_DEBUG);
        }
    }
}