我有一个Android应用程序,我需要将变量(仪器)传递给它的主要活动。这似乎是一个简单的问题,但它让我感到困惑。我环顾四周,我已经注意到编写一个getInstrument方法似乎是一个好主意。这就是我到目前为止所做的:
public class MainActivity extends Activity{
//I need to read the instrument variable here
public void addListenerOnSpinnerItemSelection(){
instrumentSp = (Spinner) findViewById(R.id.instrument);
instrumentSp.setOnItemSelectedListener(new CustomOnItemSelectedListener());
}
}
单独的类(在单独的文件中):
public class CustomOnItemSelectedListener implements OnItemSelectedListener {
private int instrument;
public void onItemSelected(AdapterView<?> parent, View view, int pos,long id) {
Toast.makeText(parent.getContext(),
"Please wait a minute for the instrument to be changed. ", Toast.LENGTH_SHORT).show();
//"Item : " + parent.getItemAtPosition(pos).toString() + " selected" + pos,
//Toast.LENGTH_SHORT).show();
instrument = pos;
}
public int getInstrument(){
return instrument;
}
}
但是我不认为我可以从main活动调用getInstrument()方法,因为该对象只存在于监听器中。必须有一个非常简单的方法。我读了一些帖子,但问题似乎是该类的对象并不存在。感谢您的任何见解。
答案 0 :(得分:1)
你可以试试这个:
public class MainActivity extends Activity{
//I need to read the instrument variable here
CustomOnItemSelectedListener MyListener = new CustomOnItemSelectedListener();
public void addListenerOnSpinnerItemSelection(){
instrumentSp = (Spinner) findViewById(R.id.instrument);
instrumentSp.setOnItemSelectedListener(MyListener);
}
}
答案 1 :(得分:1)
如果你有一个对你的听众的引用,你应该能够调用它的方法,例如
CustomOnItemSelectedListener listener = new CustomOnItemSelectedListener();
instrumentSp.setOnItemSelectedListener(listener);
....
int instrumentValue = listener.getInstrument();
答案 2 :(得分:0)
创建
的全局实例CustomOnItemSelectedListener listener;
int instrument;
public void onCreate(Bundle b){
listener = new CustomOnItemSelectedListener();
instrument = listener.getInstrument();
}
这将在MainActivity类
上