android - 微调开始活动

Question

我在从微调器开始活动时遇到问题。当我更改微调器活动的值时，开始，但是当我按下后退按钮时，我无法返回选择另一个微调器值。它存储我的选择并一次又一次地开始活动，类似于循环。

spiner1=(Spinner) findViewById(R.id.spiner1);

        spiner1.setOnItemSelectedListener(new OnItemSelectedListenerWrapper(new OnItemSelectedListener() {
@Override
            public void onItemSelected(AdapterView<?> arg0, View arg1,
                    int arg2, long arg3) {

                String str=spiner1.getSelectedItem().toString();
//              Toast.makeText(getApplicationContext(), str, Toast.LENGTH_SHORT).show();

                if(str.equals("Pravougaonik")) {
                    Intent i=new Intent(Pocetna.this, Pravougaonik.class);
                    startActivity(i);
                }
                if(str.equals("Trougao")) {
                    Intent i=new Intent(Pocetna.this, Trougao.class);
                    startActivity(i);
}
}
@Override
            public void onNothingSelected(AdapterView<?> arg0) {
                // TODO Auto-generated method stub

            }

和类：

public class OnItemSelectedListenerWrapper implements OnItemSelectedListener {

    private int lastPosition;
    private OnItemSelectedListener listener;

    public OnItemSelectedListenerWrapper(OnItemSelectedListener aListener) {
        lastPosition = 0;
        listener = aListener;
    }

    @Override
    public void onItemSelected(AdapterView<?> aParentView, View aView, int aPosition, long anId) {
        if (lastPosition == aPosition) {
            Log.d(getClass().getName(), "Ignoring onItemSelected for same position: " + aPosition);
        } else {
            Log.d(getClass().getName(), "Passing on onItemSelected for different position: " + aPosition);
            listener.onItemSelected(aParentView, aView, aPosition, anId);
        }
        lastPosition = aPosition;
    }

    @Override
    public void onNothingSelected(AdapterView<?> aParentView) {
        listener.onNothingSelected(aParentView);
    }
}