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);
} …

我看过类似的问题并尝试了他们的解决方案,但它对我不起作用.我尝试获取imageView的宽度,但它返回0.这是代码:

public class MainActivity extends Activity {
private ImageView image1;   
float centerX,centerY;
private ImageView image2;
private boolean isFirstImage = true;

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.rotate);
    image1 = (ImageView) findViewById(R.id.ImageView01);
    image2 = (ImageView) findViewById(R.id.ImageView02);
    image2.setVisibility(View.GONE);

    if (isFirstImage) {
        applyRotation(0, 90);
        isFirstImage = !isFirstImage;
    }   
}   

private void applyRotation(float start, float end) {


            centerX=image1.getWidth()/2.0f;
    centerY=image1.getHeight()/2.0f;
    final Flip3dAnimation rotation =

    new Flip3dAnimation(start, end,centerX , centerY);
    rotation.setDuration(500);
    rotation.setFillAfter(true);
    rotation.setInterpolator(new AccelerateInterpolator());
    rotation.setAnimationListener(new DisplayNextView(isFirstImage, image1,
            image2));

    if (isFirstImage)
    {
        image1.startAnimation(rotation);
    } else { …