your project contains error(s),please fix them before running your application解决方案

your project contains error(s),please fix them before running your application
如标题所示 eclipse中的 其中代码无显示任何错误 网上查阅良久 说什么重启或者删除项目重新导入 均试过 无效 就一个简单的spinner的练习 mars老师的 那么代码附上
package my.packge;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class SpinnerActivity extends Activity {
  /** Called when the activity is first created. */
private Spinner spinner = null;
 
  @Override
  public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  spinner=(Spinner)findViewById(R.id.spinnerId);
  ArrayAdapter<CharSequence> hsb=ArrayAdapter.createFromResource(this, R.array.planets_array, android.R.layout.simple_spinner_item);
  hsb.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
  spinner.setAdapter(hsb);
  spinner.setPrompt("测试");
  spinner.setOnItemSelectedListener(new SpinnerOnSelectedListener());
  }
  public class SpinnerOnSelectedListener implements OnItemSelectedListener{
  public void onItemSelected(AdapterView<?> adapterView, View view, int position,
  long id) {
  String selected = adapterView.getItemAtPosition(position).toString();
  System.out.println(selected);
  }

  public void onNothingSelected(AdapterView<?> adapterView) {
  System.out.println("nothingSelected");
  }}
  }

------解决方案--------------------
eclipse 里面有个窗口叫做Problem 看看里面的error是什么