怎样用java代码通过图片名设置linearlayout的背景图片

[youdiving]

我想在自定义Myview类的类文件中通过图片名给Main_Activity的linearlayout设置背景图片，图片存在drawable文件夹里，
public class MainActivity extends Activity
{
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

LinearLayout in;
}

public void setbackgroundpicture(String imagename)
{
int resid=getResources().getIdentifier(imagename,"drawable","com.example.ybhy");
//in.setBackground(getResources().getDrawable(resid));
System.out.println(resid);
in.setBackgroundResource(resid);

}}

public class MyView extends View
{
MainActivity ay;
public MyView(Context context, AttributeSet attrs)
{
super(context, attrs);
ay = (MainActivity) context;
...
}

public boolean onTouchEvent(MotionEvent event)
{
...
db=dbhelp.getReadableDatabase();
Cursor cur=db.rawQuery("select imgname from zipic where zi=?",new String[]{cs.toString()});

while(cur.moveToNext())
{
String picname=cur.getString(cur.getColumnIndex("imgname"));
System.out.println(picname);
ay.setbackgroundpicture(picname);//出错
}
...
}
｝
数据库里取出的图片名字是有的
LOgcat里面出现下面的错误：
05-05 08:46:07.789: I/ System.out(8560): kou01
05-05 08:46:07.789: I/ System.out(8560): 2130837516
05-05 08:46:07.889: D/ dalvikvm(8560): GC_FOR_ALLOC freed 1690K, 17% free 19108K/22791K, paused 69ms
05-05 08:46:07.934: I/ dalvikvm-heap(8560): Grow heap (frag case) to 21.225MB for 2601952-byte allocation
05-05 08:46:08.168: D/ dalvikvm(8560): GC_CONCURRENT freed 17K, 15% free 21631K/25351K, paused 8ms+26ms
05-05 08:46:08.469: D/ AndroidRuntime(8560): Shutting down VM
05-05 08:46:08.469: W/ dalvikvm(8560): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
05-05 08:46:08.530: E/ AndroidRuntime(8560): FATAL EXCEPTION: main
05-05 08:46:08.530: E/ AndroidRuntime(8560): java.lang.ArrayIndexOutOfBoundsException: length=0; index=0
05-05 08:46:08.530: E/ AndroidRuntime(8560): at com.example.ybhy.MyView.onTouchEvent(MyView.java:207)

[CuGBabyBeaR]

奇怪 为啥你放在res里的图片还要把信息存在数据库里? 直接用个数组或者放XML的Array里不就行了? 何必多此一举... 另外 每次触摸屏幕都要访问一次数据库...这...

[youdiving]

这个主要是图片名字不好定，这个地方后续会改进的

[youdiving]

自己顶一下，好像要沉了

[carvinliao]

Resources resources = getContext().getResources(); Drawable btnDrawable = resources.getDrawable(R.drawable.layout_bg); layout.setBackgroundDrawable(btnDrawable);