public class MainActivity extends Activity{private MainActivity(){};private static MainActivity mainActivity;public static MainActivity getmainActivity(){mainActivity=new MainActivity();return mainActivity;}@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Button dailButton= (Button) findViewById(R.id.bt_call);dailButton.setOnClickListener(new Mylistener());}}public class Mylistener implements OnClickListener {@Overridepublic void onClick(View v) {MainActivity mActivity=MainActivity.getmainActivity();EditText telEditText=(EditText)mActivity.findViewById(R.id.et_telNum);String number=telEditText.getText().toString();Intent intent=new Intent();intent.setAction(Intent.ACTION_CALL);intent.setData(Uri.parse("tel:"+number));mActivity.startActivity(intent);}}著了監聽類我不想把它放在mainActivity類的內部，但是在外部調用mainActivity的方法時還得new對象而且new出來的也不是同一個對象。能不能設計成單例的呢？這樣好像編譯不通過，有沒有別的辦法