android studio实现计时器代码

以下是一个简单的计时器实现代码：

public class MainActivity extends AppCompatActivity {

    private TextView mTimerTextView;
    private Button mStartButton;
    private Button mStopButton;
    private Button mResetButton;

    private CountDownTimer mCountDownTimer;
    private long mTimeLeftInMillis;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mTimerTextView = findViewById(R.id.timer_text);
        mStartButton = findViewById(R.id.start_button);
        mStopButton = findViewById(R.id.stop_button);
        mResetButton = findViewById(R.id.reset_button);

        mStartButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startTimer();
            }
        });

        mStopButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                stopTimer();
            }
        });

        mResetButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                resetTimer();
            }
        });
    }

    private void startTimer() {
        mCountDownTimer = new CountDownTimer(mTimeLeftInMillis, 1000) {
            @Override
            public void onTick(long millisUntilFinished) {
                mTimeLeftInMillis = millisUntilFinished;
                updateTimer();
            }

            @Override
            public void onFinish() {
                mStartButton.setEnabled(true);
                mStopButton.setEnabled(false);
            }
        }.start();

        mStartButton.setEnabled(false);
        mStopButton.setEnabled(true);
    }

    private void stopTimer() {
        mCountDownTimer.cancel();
        mStartButton.setEnabled(true);
        mStopButton.setEnabled(false);
    }

    private void resetTimer() {
        mTimeLeftInMillis = 60000; // 初始值为60秒
        updateTimer();
        mStartButton.setEnabled(true);
        mStopButton.setEnabled(false);
    }

    private void updateTimer() {
        int minutes = (int) (mTimeLeftInMillis / 1000) / 60;
        int seconds = (int) (mTimeLeftInMillis / 1000) % 60;

        String timeLeftFormatted = String.format(Locale.getDefault(), "%02d:%02d", minutes, seconds);
        mTimerTextView.setText(timeLeftFormatted);
    }
}

在布局文件中添加以下代码：

<TextView
    android:id="@+id/timer_text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="00:00"
    android:textSize="48sp"
    android:layout_gravity="center_horizontal"/>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:orientation="horizontal"
    android:layout_marginTop="48dp">

    <Button
        android:id="@+id/start_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start"/>

    <Button
        android:id="@+id/stop_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Stop"
        android:enabled="false"
        android:layout_marginLeft="24dp"/>

    <Button
        android:id="@+id/reset_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Reset"
        android:layout_marginLeft="24dp"/>

</LinearLayout>

这样就完成了一个简单的计时器的实现。