content: /*
   * Created on Jul 22, 2008
   * 
   * 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.
   * 
   * Copyright @2008-2013 the original author or authors.
   */
  package org.fest.swing.edt;
  
  import static javax.swing.SwingUtilities.isEventDispatchThread;
  import static org.fest.swing.exception.ActionFailedException.actionFailure;
  
  import javax.annotation.Nullable;
  
  import org.fest.swing.exception.ActionFailedException;
  
  /**
   * Executes in the event dispatch thread (EDT) an action that returns a value.
   * 
   * @param <T> the return type of the action to execute.
   * 
   * @author Alex Ruiz
   */
  public abstract class GuiQuery<T> extends GuiAction {
    private T result;
  
    /**
     * Executes the query in the event dispatch thread (EDT.) This method waits until the action has finish its execution.
     * 
     * @throws ActionFailedException if this task is not executed in the event dispatch thread (EDT.)
     */
    @Override
    public final void run() {
      if (!isEventDispatchThread()) {
        throw actionFailure("Query should be executed in the event dispatch thread");
      }
      try {
        result = executeInEDT();
      } catch (Throwable t) {
        catchedException(t);
      } finally {
        notifyExecutionCompleted();
      }
    }
  
    /**
     * Specifies the action to execute in the event dispatch thread (EDT.)
     * 
     * @return the result of the execution of the action.
     * @throws Throwable any error thrown when executing an action in the event dispatch thread (EDT.)
     */
    protected abstract @Nullable T executeInEDT() throws Throwable;
  
    final @Nullable T result() {
      return result;
    }
  
    final void clearResult() {
      result = null;
    }
  }
  