android viewflipper using animation

this is my coding for flip the string sequentially in animation view.

import android.app.Activity;
import android.os.Bundle;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ViewFlipper;

public class mukesh extends Activity {
static String[] items={"lorem", "ipsum", "dolor", "sit", "amet",
"consectetuer", "adipiscing", "elit",
"morbi", "vel", "ligula", "vitae",
"arcu", "aliquet", "mollis", "etiam",
"vel", "erat", "placerat", "ante",
"porttitor", "sodales", "pellentesque",
"augue", "purus"};
ViewFlipper flipper;
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
flipper=(ViewFlipper)findViewById(R.id.details);
flipper.setInAnimation(AnimationUtils.loadAnimation(this,
R.anim.push_left_in));
flipper.setOutAnimation(AnimationUtils.loadAnimation(this,
R.anim.push_left_out));
for (String item : items) {
Button btn=new Button(this);
btn.setText(item);
flipper.addView(btn,

new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.FILL_PARENT));
}
flipper.setFlipInterval(2000);
flipper.startFlipping();
}
} 

but "R.anim.push_l开发者_JAVA技巧eft_in" this line shows the error.R.anim cannot be resolved .whats problem. how can we solve it

Check if you have the file push_left_in.xml in the res/anim folder.

If you're using Eclipse and you can confirm that you have the file there, try to clean the project (Menu / Project / Clean), then try building it again.