android開發：退出程式（對話方塊、兩次返回鍵退出）

貼代碼：

public void exitclick(View view)    {        AlertDialog.Builder aa=new AlertDialog.Builder(this);         aa.setTitle("訊息提示");        aa.setMessage("確認退出？");         aa.setIcon(R.drawable.icon);        aa.setPositiveButton("確定",new DialogInterface.OnClickListener() {                        @Override            public void onClick(DialogInterface dialog, int which) {                // TODO Auto-generated method stub                MainActivity.this.finish();            }        });        aa.setNegativeButton("取消", null);        aa.create();         aa.show();         //this.finish();    }

感覺比C#的複雜呀。。。

還有就是按返回鍵提示退出，繼續貼代碼：

private void exitDialog()    {        AlertDialog.Builder aa=new AlertDialog.Builder(this);         aa.setTitle("訊息提示");        aa.setMessage("確認退出？");         aa.setIcon(R.drawable.icon);        aa.setPositiveButton("確定",new DialogInterface.OnClickListener() {                        @Override            public void onClick(DialogInterface dialog, int which) {                // TODO Auto-generated method stub                MainActivity.this.finish();            }        });        aa.setNegativeButton("取消", null);        aa.create();         aa.show();     }        @Override    public boolean onKeyDown(int keyCode, KeyEvent event)    {        if(keyCode == KeyEvent.KEYCODE_BACK)        {        exitDialog();        }        return true;            }

現在還流行連續按兩次返回退出，代碼：

    private static boolean isExit=false;    private static boolean hasTask=false;    Timer tExit=new Timer();    TimerTask task=new TimerTask() {                @Override        public void run() {            // TODO Auto-generated method stub            isExit=false;            hasTask=true;        }    };@Override    public boolean onKeyDown(int keyCode, KeyEvent event)    {        if(keyCode == KeyEvent.KEYCODE_BACK)        {            //exitDialog();            if(isExit==false)            {                isExit=true;                Toast.makeText(this, "再按一次退出程式", Toast.LENGTH_SHORT).show();                 if(!hasTask) {                    tExit.schedule(task, 2000);                }            }            else            {                finish();                System.exit(0);            }                    }        //return true;        return false;            }