android - 微调器下拉列表不显示

Question

http://i.stack.imgur.com/HGsTw.jpg 这是我得到的错误，应用程序崩溃了，什么也没显示！。

PS：当我将最后 4 行代码从 OnCreate 方法移动到 OnItemSelected 方法的开头时，我没有收到任何错误，并且此布局（http://i.stack.imgur.com/1DiLI.jpg）显示但没有下拉菜单列表（当我单击背景旁边的箭头按钮时，我希望有一个颜色列表）。

这是我的代码：

public class SetLayout extends Activity implements OnItemSelectedListener {
TextView o_markertv, x_markertv, bcktv, gridtv;
String[] colors ={"Red", "Green", "Blue", "Black", "White"};
Spinner spinner1, spinner2, spinner3, spinner4;
LinearLayout bck;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.setlayout);
    bck= (LinearLayout) findViewById(R.id.bck);

    o_markertv= (TextView) findViewById(R.id.o_markertv);
    x_markertv= (TextView) findViewById(R.id.x_markertv);
    bcktv= (TextView) findViewById(R.id.bcktv);
    gridtv= (TextView) findViewById(R.id.gridtv);
    spinner1 = (Spinner) findViewById(R.id.spinner1);
    spinner2 = (Spinner) findViewById(R.id.spinner2);
    spinner3 = (Spinner) findViewById(R.id.spinner3);
    spinner4 = (Spinner) findViewById(R.id.spinner4);
    //Button BtnSubmit = (Button) findViewById(R.id.btnSubmit);

    ArrayAdapter<String> adapter=new ArrayAdapter<String> (SetLayout.this,android.R.layout.simple_spinner_item,colors);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner1.setAdapter(adapter);
    spinner1.setOnItemSelectedListener(this);
}


@Override
public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
        long arg3) {



    int position= spinner1.getSelectedItemPosition();
    switch(position){ //red, green blue black white
    case 0:
        bck.setBackgroundColor(color.red);
        break;
    case 1:
        bck.setBackgroundColor(color.green);
        break;
    case 2:
        bck.setBackgroundColor(color.blue);
        break;
    case 3:
        bck.setBackgroundColor(color.black);
        break;
    case 4:
        bck.setBackgroundColor(color.white);
        break;

    }
}

@Override
public void onNothingSelected(AdapterView<?> arg0) {
    // TODO Auto-generated method stub

}

}