Android：动画不起作用

Question

我正在使用Android应用。这个程序有教程屏幕。在本教程中，用户必须向右和向左滑动才能完成教程。当它启动应用程序时，它会显示名为SwipeLeftFragment的第一个片段。当用户向左滑动时，它会显示名为SwipeRightFragment的第二个片段。当用户向右滑动时，它会显示名为CompletedTutorialFragment的第三个片段。 目前它工作正常但动画不起作用。 以下是我的代码：

public class TutorialActivity extends FragmentActivity {
@Override
protected void onStart() {
    super.onStart();
    final swipeLeftFragment swipeLeftFragment = new SwipeLeftFragment();
    addFragmentToBottom(swipeLeftFragment);


    swipeLeftFragment.getView().setOnTouchListener(new OnSwipeListener(TutorialActivity.this) {
        @Override
        public void onSwipeRight() {

        }

        @Override
        public void onSwipeLeft() {
            TranslateAnimation animation = new TranslateAnimation(0, -swipeLeftFragment.getView().getWidth(), 0, 0);
            animation.setDuration(5000);
            swipeLeftFragment.getView().startAnimation(animation);
            swipeLeftFragment.getView().setVisibility(View.GONE);
            final SwipeRightFragment swipeRightFragment = new SwipeRightFragment();
            addFragmentToBottom(swipeRightFragment);
            swipeRightFragment.getView().setOnTouchListener(new OnSwipeListener(TutorialActivity.this) {
                @Override
                public void onSwipeRight() {
                    TranslateAnimation animation = new TranslateAnimation(0, +swipeRightFragment.getView().getWidth(), 0, 0);
                    animation.setDuration(5000);
                    swipeRightFragment.getView().startAnimation(animation);
                    swipeRightFragment.getView().setVisibility(View.GONE);
                    final CompletedTutorialFragment completedTutorialFragment = new CompletedTutorialFragment();
                    addFragmentToBottom(completedTutorialFragment);
                    startSignupActivity();
                }

                @Override
                public void onSwipeLeft() {

                }
            });
        }
    });
}

private void startSignupActivity() {
    Handler mHandler = new Handler();
    mHandler.postDelayed(new Runnable() {

        @Override
        public void run() {
            startActivity(new Intent(TutorialActivity.this, SignUpActivity.class));
        }

    }, 2000L);
}
}

有人能告诉我我的代码有什么问题吗？

这是 OnTouchListener我正在使用