android studio 计时器暂停后将时间保存到SQLite数据库

要将计时器暂停后将时间保存到SQLite数据库，您可以按照以下步骤操作：

1. 声明一个变量来保存计时器的当前时间，例如long currentTime。

2. 在计时器的onTick方法中每次更新currentTime变量。

3. 在计时器暂停的时候，将currentTime保存到SQLite数据库中。您可以使用ContentValues类来创建一个包含currentTime的数据行，然后使用SQLiteOpenHelper类的insert方法将其插入到数据库中。

4. 在恢复计时器时，从SQLite数据库中获取之前保存的currentTime值，并使用它来重新开始计时器。

下面是一个示例代码，演示如何实现这个功能：

public class MainActivity extends AppCompatActivity {

    private CountDownTimer mCountDownTimer;
    private TextView mTextViewCountdown;
    private Button mButtonStartPause;
    private Button mButtonReset;

    private boolean mTimerRunning;
    private long mTimeLeftInMillis;
    private long mEndTime;

    private SQLiteDatabase mDatabase;

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

        mTextViewCountdown = findViewById(R.id.text_view_countdown);
        mButtonStartPause = findViewById(R.id.button_start_pause);
        mButtonReset = findViewById(R.id.button_reset);

        mButtonStartPause.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mTimerRunning) {
                    pauseTimer();
                } else {
                    startTimer();
                }
            }
        });

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

        // Initialize the database
        DBHelper dbHelper = new DBHelper(this);
        mDatabase = dbHelper.getWritableDatabase();

        // Load the saved time from the database
        Cursor cursor = mDatabase.query(DBHelper.TABLE_NAME, null, null, null, null, null, null);
        if (cursor.moveToFirst()) {
            mTimeLeftInMillis = cursor.getLong(cursor.getColumnIndex(DBHelper.COLUMN_TIME_LEFT));
            updateCountdownText();
            startTimer();
        } else {
            resetTimer();
        }
        cursor.close();
    }

    private void startTimer() {
        mEndTime = System.currentTimeMillis() + mTimeLeftInMillis;

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

            @Override
            public void onFinish() {
                mTimerRunning = false;
                mButtonStartPause.setText("Start");
                mButtonStartPause.setVisibility(View.INVISIBLE);
                mButtonReset.setVisibility(View.VISIBLE);
            }
        }.start();

        mTimerRunning = true;
        mButtonStartPause.setText("Pause");
        mButtonReset.setVisibility(View.INVISIBLE);
    }

    private void pauseTimer() {
        mCountDownTimer.cancel();
        mTimerRunning = false;
        mButtonStartPause.setText("Start");
        mButtonReset.setVisibility(View.VISIBLE);

        // Save the current time to the database
        ContentValues values = new ContentValues();
        values.put(DBHelper.COLUMN_TIME_LEFT, mTimeLeftInMillis);
        mDatabase.update(DBHelper.TABLE_NAME, values, null, null);
    }

    private void resetTimer() {
        mTimeLeftInMillis = 60000;
        updateCountdownText();
        mButtonStartPause.setVisibility(View.VISIBLE);
        mButtonReset.setVisibility(View.INVISIBLE);

        // Save the default time to the database
        ContentValues values = new ContentValues();
        values.put(DBHelper.COLUMN_TIME_LEFT, mTimeLeftInMillis);
        mDatabase.insert(DBHelper.TABLE_NAME, null, values);
    }

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

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

    private static class DBHelper extends SQLiteOpenHelper {

        private static final String DATABASE_NAME = "timer.db";
        private static final int DATABASE_VERSION = 1;

        private static final String TABLE_NAME = "timer";
        private static final String COLUMN_TIME_LEFT = "time_left";

        private static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" +
                COLUMN_TIME_LEFT + " INTEGER)";

        private static final String DROP_TABLE = "DROP TABLE IF EXISTS " + TABLE_NAME;

        public DBHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL(CREATE_TABLE);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL(DROP_TABLE);
            onCreate(db);
        }
    }
}

在这个示例中，我们在onCreate方法中初始化了SQLite数据库，并在恢复计时器时从中加载了之前保存的时间。当暂停计时器时，我们使用ContentValues类来创建一个包含当前时间的数据行，并使用update方法将其更新到数据库中。在重置计时器时，我们使用insert方法向数据库中插入一个包含默认时间的数据行。