Question

我无法理解为什么此代码不显示任何Toast。我已经实现了OnGestureListener接口并尝试在用户时显示一些toast 滑动活动。这意味着必须调用onFling方法，但我没有收到任何吐司。请帮我理解这个问题。

import android.os.Bundle;
import android.app.Activity;
import android.view.GestureDetector.OnGestureListener;
import android.view.Menu;
import android.view.MotionEvent;
import android.widget.Toast;

public class MainActivity extends Activity implements OnGestureListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onDown(MotionEvent e) {
    // TODO Auto-generated method stub
    Toast.makeText(this,"onDown",Toast.LENGTH_LONG).show();
    return false;
}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
        float velocityY) {
    // TODO Auto-generated method stub
    Toast.makeText(this,"Swipe to Explore the Happiness Path",Toast.LENGTH_LONG).show();
    return false;
}

@Override
public void onLongPress(MotionEvent e) {
    // TODO Auto-generated method stub
    Toast.makeText(this,"onLongPress",Toast.LENGTH_LONG).show();

}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
        float distanceY) {
    // TODO Auto-generated method stub
    return false;
}

@Override
public void onShowPress(MotionEvent e) {
    // TODO Auto-generated method stub

}

@Override
public boolean onSingleTapUp(MotionEvent e) {
    // TODO Auto-generated method stub`enter code here`
    return false;
}

}

Answer 1

GestureDetector是一个可以拍摄动作事件的Android类一些数学魔法来确定它们是什么，然后委托调用GestureListener对象作为特定手势或其他动作回调。 GestureListener对象是我们实现的类，它接收这些调用是GestureDetector识别的特定手势并允许我们按照我们认为合适的方式对它们作出反应（在这种情况下，移动一个我们的PlayAreaView内的图形）。虽然是GestureDetector 处理某些动作的检测，它什么都不做与他们特定，也不处理所有类型的手势。

尝试如下添加GestureDetector并实施onTouch事件来检测屏幕触摸：

public class MainActivity extends Activity implements OnGestureListener {

private GestureDetector gDetector;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
gDetector = new GestureDetector(this);
}
 @Override
public boolean onTouchEvent(MotionEvent me) {
    return gDetector.onTouchEvent(me);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onDown(MotionEvent e) {
    // TODO Auto-generated method stub
    Toast.makeText(this,"onDown",Toast.LENGTH_LONG).show();
    return false;
}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
        float velocityY) {
    // TODO Auto-generated method stub
    Toast.makeText(this,"Swipe to Explore the Happiness Path",Toast.LENGTH_LONG).show();
    return false;
}

@Override
public void onLongPress(MotionEvent e) {
    // TODO Auto-generated method stub
    Toast.makeText(this,"onLongPress",Toast.LENGTH_LONG).show();

}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
        float distanceY) {
    // TODO Auto-generated method stub
    return false;
}

@Override
public void onShowPress(MotionEvent e) {
    // TODO Auto-generated method stub

}

@Override
public boolean onSingleTapUp(MotionEvent e) {
    // TODO Auto-generated method stub`enter code here`
    return false;
}
}

了解更多GestureDetector

了解OnGestureListener以进行滑动

1 个答案: