Question

我在名为GameLoop的类中使用此代码（代码类似于LunarLander示例）

while( running ) {
    Canvas canvas = null;
    try {
        canvas = mSurfaceHolder.lockCanvas(null);
        long t = System.currentTimeMillis();
        if( t - old[0] >= frame ) {
            old[0] = t;
            synchronized( mSurfaceHolder ) {
                mGame.update();
                mGame.onDraw(canvas);
            }
        }
    }
    finally {
        // Do this in finally so that if an exception is thrown
        // we don't leave the Surface in an inconsistent state
        if( canvas != null ) mSurfaceHolder.unlockCanvasAndPost(canvas);
    }

        }

父类是GameView（参考mGame）当mGame.update()尝试调用自己的announce方法时，

public class GameView extends SurfaceView implements SurfaceHolder.Callback {

. . .
    private void announce(int resId) {
        synchronized( mSurfaceHolder ) {
            tv_announcement.setText(getContext().getString(resId));
            ObjectAnimator anim = ObjectAnimator.ofFloat(tv_announcement, "alpha", 0, 1);
            anim.setDuration(ANNOUNCE_DURATION).start();
        }
    }
. . .

我得到了这个例外：

 android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

这里有两个主题， UI线程，它运行GameView并拥有SurfaceView，和GameLoop ，它是Thread的扩展，只运行update-draw循环。

据我所知，异常告诉我只有UI线程才能触及TextView tv_announcement。
但是不是announce在UI线程中运行？我在这里缺少什么？

这是宣布后异常的logcat：

03-22 07:20:19.096: D/GameView(28250): + update(): state:IDLE, next state:CHOOSE_SIDE
03-22 07:20:19.096: D/GameView(28250): + announce(resId:2131361803)
03-22 07:20:19.096: W/dalvikvm(28250): threadid=10: thread exiting with uncaught exception (group=0xb3040180)
03-22 07:20:19.096: E/AndroidRuntime(28250): FATAL EXCEPTION: Thread-192
03-22 07:20:19.096: E/AndroidRuntime(28250): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4039)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:709)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.View.requestLayout(View.java:12675)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.View.requestLayout(View.java:12675)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.View.requestLayout(View.java:12675)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.View.requestLayout(View.java:12675)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.View.requestLayout(View.java:12675)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:268)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.view.View.requestLayout(View.java:12675)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.widget.TextView.checkForRelayout(TextView.java:6773)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.widget.TextView.setText(TextView.java:3306)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.widget.TextView.setText(TextView.java:3162)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at android.widget.TextView.setText(TextView.java:3137)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at <package>.GameView.announce(GameView.java:436)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at  <package>.GameView.update(GameView.java:314)
03-22 07:20:19.096: E/AndroidRuntime(28250):    at  <package>.GameView$GameLoop.run(GameView.java:495)
03-22 07:20:19.126: D/GameView(28250): + onWindowFocusChanged(hasWindowFocus:true)
03-22 07:20:19.126: D/GameView(28250): - onWindowFocusChanged()

Answer 1

只有创建视图层次结构的原始线程才能触及它视图。

您的错误被抛出，因为您确实要从非线程修改UI，可能是来自工作线程。

如果您想使用Thread中执行的操作或仅使用Thread中执行的某些过程更新UI，您只能使用：

哪一个是创建视图的原始线程？

1 个答案: