Android编辑系统文件

Question

我最近开始为android开发我的第一个应用程序，我有点卡住了。我的应用程序使用了CountDownTimer类，似乎malfuncions - CountDownTimer.cancel()不起作用。我知道如何通过修改CountDownTimer.java文件来修复这个问题，但我没有这样做的权限。我在Android Studio工作。我在网上找不到一个解释，尽管这似乎是一个很基本的问题，不是吗？也许我用的词不对？

非常感谢你的帮助，如果我的问题有点无知，我道歉哈哈。

Answer 1

尝试这样做：

public class Main extends Activity implements OnClickListener
    {
        private static final String tag = "Main";
        private MalibuCountDownTimer countDownTimer;
        private long timeElapsed;
        private boolean timerHasStarted = false;
        private Button startB;
        private TextView text;
        private TextView timeElapsedView;

        private final long startTime = 50000;
        private final long interval = 1000;

        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState)
            {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.main);
                startB = (Button) this.findViewById(R.id.button);
                startB.setOnClickListener(this);

                text = (TextView) this.findViewById(R.id.timer);
                timeElapsedView = (TextView) this.findViewById(R.id.timeElapsed);
                countDownTimer = new MalibuCountDownTimer(startTime, interval);
                text.setText(text.getText() + String.valueOf(startTime));
            }

        @Override
        public void onClick(View v)
            {
                if (!timerHasStarted)
                    {
                        countDownTimer.start();
                        timerHasStarted = true;
                        startB.setText("Start");
                    }
                else
                    {

                        countDownTimer.cancel();
                        timerHasStarted = false;
                        startB.setText("RESET");
                    }
            }

        // CountDownTimer class
        public class MalibuCountDownTimer extends CountDownTimer
            {

                public MalibuCountDownTimer(long startTime, long interval)
                    {
                        super(startTime, interval);
                    }

                @Override
                public void onFinish()
                    {
                        text.setText("Time's up!");
                        timeElapsedView.setText("Time Elapsed: " + String.valueOf(startTime));
                    }

                @Override
                public void onTick(long millisUntilFinished)
                    {
                        text.setText("Time remain:" + millisUntilFinished);
                        timeElapsed = startTime - millisUntilFinished;
                        timeElapsedView.setText("Time Elapsed: " + String.valueOf(timeElapsed));
                    }
            }
    }

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