java - 如何设置一个按钮的位置随机新？

Question

当我点击“开始时间”按钮时，它有时会完全移出屏幕，这很糟糕。而且，对我来说，按钮的放置不够随机，有时单击一下，它只是向下移动了一点。最后，应用程序没有得到时间，而是以 nullpointer 停止。 Button 应该留在屏幕上，在点击时随机放置在新位置，点击几下后，我想接收耗时。为什么这不起作用？

代码:

@Override

public void onClick(View v) {

Button b = (Button) findViewById(R.id.start_time);

    Random r = new Random();
    View decorView = getWindow().getDecorView();
    int screenWidth = decorView.getWidth();
    int screenHeight = decorView.getHeight();
      long startTime =  SystemClock.elapsedRealtime();
      i++;
/*  
        Random r = new Random();

    int x = r.nextInt(R.id.wrap_content);
      int y = r.nextInt(R.id.wrap_content);




    b.setX(x);  
    b.setY(y);
     */ 

    if (i == 1 ) {

        start_time.setX(r.nextInt(screenWidth - start_time.getWidth()));
        start_time.setY(r.nextInt(screenHeight - start_time.getHeight()));
    }
    if (i == 2 ) {
        start_time.setX(r.nextInt(screenWidth - start_time.getWidth()));
        start_time.setY(r.nextInt(screenHeight - start_time.getHeight()));
    }
    if (i == 3 ) {
        start_time.setX(r.nextInt(screenWidth - start_time.getWidth()));
        start_time.setY(r.nextInt(screenHeight - start_time.getHeight()));
    }
    if (i == 4 ) {
        start_time.setX(r.nextInt(screenWidth - start_time.getWidth()));
        start_time.setY(r.nextInt(screenHeight - start_time.getHeight()));
    }
    if (i == 5 ) {
        start_time.setX(r.nextInt(screenWidth - start_time.getWidth()));
        start_time.setY(r.nextInt(screenHeight - start_time.getHeight()));
    }
    if (i == 6 ) {
        start_time.setX(r.nextInt(screenWidth - start_time.getWidth()));
        start_time.setY(r.nextInt(screenHeight - start_time.getHeight()));
    }
    else if (i == 7) {
        long difference = SystemClock.elapsedRealtime()  - startTime;

          Intent intent = new Intent(Game.this, MainScreen.class);
          intent.putExtra("time",difference);
         // Toast.makeText(getApplicationContext(), getIntent().getStringExtra("time"), Toast.LENGTH_LONG).show();
          textview1.setText(getIntent().getStringExtra("time"));
        finish();
    }


}

和 xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clickable="true"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="chdfss.dsfwegg.trhhGame" >

    <Button
        android:id="@+id/start_time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="139dp"
        android:text="Button" />




</RelativeLayout>

Answer 1

我不会使用边距。那是老办法。如果您支持 Android 3.0+，则可以使用 View 属性将它们放在任何地方。

所以像这样:

Random rand = new Random();
View decorView = getWindow().getDecorVew();
int screenWidth = decorView.getWidth();
int screenHeight = decorView.getHeight();
...
// when you want to move the button.

view.setX(rand.nextInt(screenWidth - view.getWidth());
view.setY(rand.nextInt(screenHeight - view.getHeight());

View#setX() 和 View#setY() 方法链接到 View 的左上角。

如果你想支持低于 3.0 的版本，那么你可以使用 NineOldAndroids动画 api 和动画，时间为 0 毫秒，因此它是即时的。