public class MainActivity extends Activity implements OnClickListener{

?EditText et;

?Button bt0;

Button bt1;

Button bt2;

?Button bt3;

Button bt4;

?Button bt5;

?Button bt6;

Button bt7;

Button bt8;

?Button bt9;

Button btplus;

Button btmin;

?Button btmul;

?Button btdiv;

?Button btpoint;

?Button btclear;

?Button btdel;

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

bt0=(Button) findViewById(R.id.button0);

bt1=(Button) findViewById(R.id.button1);

bt2=(Button) findViewById(R.id.button2);

bt3=(Button) findViewById(R.id.button3);

bt4=(Button) findViewById(R.id.button4);

bt5=(Button) findViewById(R.id.button5);

bt6=(Button) findViewById(R.id.button6);

bt7=(Button) findViewById(R.id.button7);

bt8=(Button) findViewById(R.id.button8);

bt9=(Button) findViewById(R.id.button9);

btplus=(Button) findViewById(R.id.buttonplu);

btmin=(Button) findViewById(R.id.buttonmin);

btdiv=(Button) findViewById(R.id.buttondiv);

btpoint=(Button) findViewById(R.id.buttondot);

btclear=(Button) findViewById(R.id.buttonc);

btdel=(Button) findViewById(R.id.buttondel);

et=(EditText) findViewById(R.id.edittext);

bt0.setOnClickListener(this);

bt1.setOnClickListener(this);

bt2.setOnClickListener(this);

bt3.setOnClickListener(this);

bt4.setOnClickListener(this);

bt5.setOnClickListener(this);

bt6.setOnClickListener(this);

bt7.setOnClickListener(this);

bt8.setOnClickListener(this);

bt9.setOnClickListener(this);

btplus.setOnClickListener(this);

btmin.setOnClickListener(this);

btmul.setOnClickListener(this);

btdiv.setOnClickListener(this);

btclear.setOnClickListener(this);

btdel.setOnClickListener(this);

btpoint.setOnClickListener(this);

}

@Override

public void onClick(View v) {

String str=et.getText().toString();//取現實屏上的內容

switch (v.getId()) {

case R.id.button0:

case R.id.button1:

case R.id.button2:

case R.id.button3:

case R.id.button4:

case R.id.button5:

case R.id.button6:

case R.id.button7:

case R.id.button8:

case R.id.button9:

case R.id.buttondot:et.setText(str+((Button)v).getText());break;

case R.id.buttonplu:

case R.id.buttonmin:

case R.id.buttonmul:

case R.id.buttondiv:et.setText(str+" "+((Button)v).getText()+" ");break;

case R.id.buttonc:et.setText("");break;

case R.id.buttondel:

if(str!=null&&!str.equals(""))

{

et.setText(str.subSequence(0, str.length()-1));

};break;

case R.id.buttonequal:

break;

}

}

}