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/*
* Copyright (C) 2022 Archie L. Cobbs. All rights reserved.
*/
package org.dellroad.stuff.vaadin24.util;
import com.google.common.base.Preconditions;
import java.util.EventObject;
/**
* Event type emitted by an {@link AsyncTaskManager} when an {@link AsyncTask} changes status.
*
* @param task result type
*/
@SuppressWarnings("serial")
public class AsyncTaskStatusChangeEvent extends EventObject {
/**
* Status value indicating that a new asynchronous task has started.
*/
public static final int STARTED = 0;
/**
* Status value indicating that an asynchronous task has completed successfully.
*/
public static final int COMPLETED = 1;
/**
* Status value indicating that an asynchronous task was {@link AsyncTaskManager#cancelTask cancelTask()}'ed
* (or canceled itself by throwing {@link InterruptedException}).
*/
public static final int CANCELED = 3;
/**
* Status value indicating that an asynchronous task failed (i.e., threw an exception).
*/
public static final int FAILED = 4;
private final long id;
private final int status;
private final R result;
private final Throwable exception;
/**
* Constructor.
*
* @param source source for this event
* @param id task unique ID
* @param result task result, or null if not {@link #COMPLETED}
* @param exception thrown exception, or null if not {@link #CANCELED} or {@link #FAILED}
* @throws IllegalArgumentException if {@code source} is null
* @throws IllegalArgumentException if {@code id} is zero
* @throws IllegalArgumentException if {@code status} is invalid
* @throws IllegalArgumentException if {@code result} or {@code exception} is inconsistent with {@code status}
*/
public AsyncTaskStatusChangeEvent(AsyncTaskManager source, long id, int status, R result, Throwable exception) {
super(source);
Preconditions.checkArgument(source != null, "null source");
Preconditions.checkArgument(id != 0, "zero id");
switch (status) {
case STARTED:
Preconditions.checkArgument(result == null, "result must be null");
Preconditions.checkArgument(exception == null, "exception must be null");
break;
case COMPLETED:
Preconditions.checkArgument(exception == null, "exception must be null");
break;
case CANCELED:
Preconditions.checkArgument(result == null, "result must be null");
break;
case FAILED:
Preconditions.checkArgument(result == null, "result must be null");
Preconditions.checkArgument(exception != null, "exception must not be null");
break;
default:
throw new IllegalArgumentException("invalid status");
}
this.id = id;
this.status = status;
this.result = result;
this.exception = exception;
}
/**
* Get the ID of the associated asynchronous task.
*
* @return task ID
*/
public long getTaskId() {
return this.id;
}
/**
* Get the new status of the associated asynchronous task: one of {@link #STARTED}, {@link #COMPLETED},
* {@link #CANCELED}, or {@link #FAILED}.
*
* @return status
*/
public int getStatus() {
return this.status;
}
/**
* Get the {@link AsyncTaskManager} that originated this event.
*
* @return event originator
*/
@Override
@SuppressWarnings("unchecked")
public AsyncTaskManager getSource() {
return (AsyncTaskManager)super.getSource();
}
/**
* Get the result from the successfully completed associated asynchronous task.
*
*
* This method returns null except when the status is {@link #COMPLETED}, in which case it returns
* the result of the task.
*
* @return task result, or null if task has not completed successfully
*/
public R getResult() {
return this.result;
}
/**
* Get the exception thrown by the associated asynchronous task that failed or was canceled.
*
*
* This method returns null except when the status is {@link #FAILED} or {@link #CANCELED},
* in which case it returns the exception thrown. In the case of {@link #CANCELED}, this will
* always be an {@link InterruptedException}.
*
* @return error thrown, or null if task has not yet finished or completed successfully
*/
public Throwable getException() {
return this.exception;
}
}