全部的R.都报错了 包括自动生成的代码 小弟刚开始学Android 希望各位前辈多多指点 谢谢了

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.app.Activity;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Spinner spinner=(Spinner)findViewById(R.id.spinner);
ArrayAdapter adapter=ArrayAdapter.createFromResource(this,R.array.colors,
android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
AdapterView.OnItemSelectedListener oisl=new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int position,
long id) {
String selected=adapterView.getItemAtPosition(position).toString();
System.out.println(“selected”);
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
System.out.println(“nothingSelected”);
}
};
spinner.setOnItemSelectedListener(oisl);
}