0
我试图使用Drawable Animation在我的一个Viewpager中。但是当我尝试使用getDrawable()
方法时,它给了我空指针异常。我的ViewPager有4页。我认为这是因为我的XML文件是在Viewpager中创建的,我无法通过此方法访问它们。我已经在我的Viewpager中设置了一个ImageView的源代码,但它仍然无效。请看看我的代码并帮助我。如何在使用ViewPager时使用getDrawable()
我的主要活动:
import android.graphics.drawable.AnimationDrawable;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new CustomPagerAdapter(this));
ImageView myAnimation = (ImageView)findViewById(R.id.imageView2);
final AnimationDrawable myAnimationDrawable = (AnimationDrawable)myAnimation.getDrawable();
myAnimationDrawable.start();
}
}
我ViewPager适配器:
import android.content.Context;
import android.graphics.drawable.AnimationDrawable;
import android.graphics.drawable.Drawable;
import android.support.v4.view.PagerAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class CustomPagerAdapter extends PagerAdapter {
private Context mContext;
public CustomPagerAdapter(Context context) {
mContext = context;
}
@Override
public Object instantiateItem(ViewGroup collection, int position) {
ModelObject modelObject = ModelObject.values()[position];
LayoutInflater inflater = LayoutInflater.from(mContext);
ViewGroup layout = (ViewGroup) inflater.inflate(modelObject.getLayoutResId(), collection, false);
collection.addView(layout);
return layout;
}
@Override
public void destroyItem(ViewGroup collection, int position, Object view) {
collection.removeView((View) view);
}
@Override
public int getCount() {
return ModelObject.values().length;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
@Override
public CharSequence getPageTitle(int position) {
ModelObject customPagerEnum = ModelObject.values()[position];
return mContext.getString(customPagerEnum.getTitleResId());
}
}
和我enum
添加新的页面:
public enum ModelObject {
RED(R.string.wp1, R.layout.wp1),
BLUE(R.string.wp2, R.layout.wp2),
LOL(R.string.wp3, R.layout.wp3),
WP(R.string.wp5,R.layout.wp4),
GREEN(R.string.wp4, R.layout.wp4);
private int mTitleResId;
private int mLayoutResId;
ModelObject(int titleResId, int layoutResId) {
mTitleResId = titleResId;
mLayoutResId = layoutResId;
}
public int getTitleResId() {
return mTitleResId;
}
public int getLayoutResId() {
return mLayoutResId;
}
}
如果可以,请帮助我。
对不起英语感到抱歉。