Android双击返回键退出程序的3种写法

1. 使用onBackPressed()方法：
@Override
public void onBackPressed() {
super.onBackPressed();
// 退出程序的操作
finish();
}
2. 使用双击返回键的计时器：
private static final long DOUBLE_BACK_PRESS_TIME = 2000; // 双击返回键的间隔时间
private long backPressTime;
@Override
public void onBackPressed() {
if (backPressTime + DOUBLE_BACK_PRESS_TIME > System.currentTimeMillis()) {
super.onBackPressed();
// 退出程序的操作
finish();
} else {
Toast.makeText(this, "再次点击返回键退出程序", Toast.LENGTH_SHORT).show();
}
backPressTime = System.currentTimeMillis();
}
3. 使用手势库GestureDetector：
private static final int SWIPE_THRESHOLD = 100; // 手势的阈值
private static final int SWIPE_VELOCITY_THRESHOLD = 100; // 手势的速度阈值
private GestureDetector gestureDetector;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// 初始化GestureDetector
gestureDetector = new GestureDetector(this, new GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
// 计算手势的速度和方向
float deltaX = e2.getX() - e1.getX();
float deltaY = e2.getY() - e1.getY();
if (Math.abs(deltaX) > Math.abs(deltaY) && Math.abs(deltaX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (deltaX > 0) {
// 右滑动，退出程序的操作
finish();
}
}
return super.onFling(e1, e2, velocityX, velocityY);
}
});
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// 将触摸事件传递给GestureDetector处理
gestureDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}