Android要使用Listener來監聽物件

//首先需在MainActivity implements監聽動作

public class MainActivity extends AppCompatActivity
implements RadioGroup.OnCheckedChangeListener,TextWatcher
{

RadioGroup unit;
EditText value;
TextView txv;

@Overrideprotected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
//設定要監聽的物件
    unit=(RadioGroup)findViewById(R.id.radioGroup);
    unit.setOnCheckedChangeListener(this);
    value=(EditText)findViewById(R.id.editText);
    value.addTextChangedListener(this);
    txv=(TextView)findViewById(R.id.textView2);

}

//以下是監聽的事件
@Overridepublic void onCheckedChanged(RadioGroup group, int checkedId) {
    calc();
}


@Overridepublic void beforeTextChanged(CharSequence s, int start, int count, int after) {

}

@Overridepublic void onTextChanged(CharSequence s, int start, int before, int count) {

}

@Overridepublic void afterTextChanged(Editable s) {
    calc();
}

protected void calc(){
   
}

}