相关疑难解决方法(0)

我动态地在我的android项目中创建所有元素.我试图获得按钮的宽度和高度,以便我可以旋转该按钮.我只是想学习如何使用android语言.但是,它返回0.

我做了一些研究,我发现它需要在onCreate()方法之外的某个地方完成.如果有人能给我一个如何做的例子,那就太好了.

这是我目前的代码:

package com.animation;

import android.app.Activity;
import android.os.Bundle;
import android.view.animation.Animation;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
import android.widget.Button;
import android.widget.LinearLayout;

public class AnimateScreen extends Activity {


//Called when the activity is first created.
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    LinearLayout ll = new LinearLayout(this);

    LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
    layoutParams.setMargins(30, 20, 30, 0);

    Button bt = new Button(this);
    bt.setText(String.valueOf(bt.getWidth()));

    RotateAnimation ra = new RotateAnimation(0,360,bt.getWidth() / 2,bt.getHeight() / 2);
    ra.setDuration(3000L);
    ra.setRepeatMode(Animation.RESTART);
    ra.setRepeatCount(Animation.INFINITE);
    ra.setInterpolator(new LinearInterpolator());

    bt.startAnimation(ra);

    ll.addView(bt,layoutParams);

    setContentView(ll);
} …

我必须使用一个OnGlobalLayoutListener对象,然后删除监听器,我有一个问题与我用以下代码解决的弃用方法.

protected void onCreate(Bundle savedInstanceState) {
    final LinearLayout llTotal = (LinearLayout) findViewById(R.id.mmc_ll);
    ViewTreeObserver vto = llTotal.getViewTreeObserver();
    if(vto.isAlive()){
        vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                //
                // mycode
                //
                if (Build.VERSION.SDK_INT<16) {
                    removeLayoutListenerPre16(llTotal.getViewTreeObserver(),this);
                } else {
                    removeLayoutListenerPost16(llTotal.getViewTreeObserver(), this);
                }
            } 
        });
    }
    super.onCreate(savedInstanceState);
}

@SuppressWarnings("deprecation")
private void removeLayoutListenerPre16(ViewTreeObserver observer, OnGlobalLayoutListener listener){
    observer.removeGlobalOnLayoutListener(listener);
}

@TargetApi(16)
private void removeLayoutListenerPost16(ViewTreeObserver observer, OnGlobalLayoutListener listener){
    observer.removeOnGlobalLayoutListener(listener);
}

这是对的吗？有更好的方法来处理兼容性？

使用API​​ 10在模拟器中运行代码我在LogCat中有以下警告

04-24 09:30:12.565: I/dalvikvm(471): Could not find method android.view.ViewTreeObserver.removeOnGlobalLayoutListener, referenced from method com.my.project.ActivityHome.removeLayoutListenerPost16
04-24 …