一个简单的加减乘除计算器，可不知道到底哪里出错了。请大神帮忙看看。安卓的。

Question

public class MainActivity extends ActionBarActivity {

private Button but1 = null;

private Button but2 = null;

private Button but3 = null;

private Button but4 = null;

private EditText edt1 = null;

private EditText edt2 = null;

private TextView tv = null;

int num1=0;

int num2=0;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.fragment_main);

this.edt1 = (EditText) super.findViewById(R.id.edt1);

this.edt2 = (EditText) super.findViewById(R.id.edt2);

this.tv = (TextView) super.findViewById(R.id.result);

this.but1.setOnClickListener(new OnClickListenerImpI());

this.but2.setOnClickListener(new OnClickListenerImpI2());

this.but3.setOnClickListener(new OnClickListenerImpI3());

this.but4.setOnClickListener(new OnClickListenerImpI4());

}

private class OnClickListenerImpI implements OnClickListener {

@Override

public void onClick(View arg0) {

// TODO Auto-generated method stub

num1=Integer.parseInt(edt1.getText().toString());

num2=Integer.parseInt(edt2.getText().toString());

int result = num1

+ num2;

tv.setText(result);

}

}

}

Answer 1

先findViewById..

Answer 2

你这是空指针异常，，，button都没有实例化出来。。。

Answer 3

附加异常错误。。