Question

我想从数据库中提取一个值并在倒数计时器中使用它。似乎它不可能与CountDownTimer一起使用，但看起来它可以通过Handler实现。任何人都可以提供一个例子吗？

我正在使用Android Studio

由于

这是我的计时器课程：

    import android.app.Activity;
    import android.database.Cursor;
    import android.os.Bundle;
    import android.os.CountDownTimer;
    import android.widget.TextView;

/**
 * Created by Mat on 14-Feb-17.
 */

    public class Timer extends Activity{

    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        textView = (TextView) findViewById(R.id.text);

        // 15000 is the starting number (in milliseconds)
        // 1000 is the number to count down each time (in milliseconds)


        MyCount counter = new MyCount(DisplayTime2(), 1000); // <--- 
        counter.start();
    }


    private long DisplayTime2(Cursor d) {  //  <------------
        return (d.getLong(2));
    }

    // count down timer is an abstract class, so extend it and fill in methods
    public class MyCount extends CountDownTimer {

        public MyCount(long millisInFuture, long countDownInterval) {
            super(millisInFuture, countDownInterval);
        }

        @Override
        public void onFinish() {
            // it's done
            textView.setText("Done!");
        }

        @Override
        public void onTick(long millisUntilFinished) {
            textView.setText("Left: " + millisUntilFinished / 1000);
        }
    }


    }

这是我的DatabaseAccess类

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import java.util.ArrayList;
import java.util.List;

public class DatabaseAccess {
private SQLiteOpenHelper openHelper;
private SQLiteDatabase database;
private static DatabaseAccess instance;
private static  String DATABASE_TABLE = "Cardio";
static final String KEY_ROWID = "rowid";
static final String KEY_NAME = "Exercise";

/**
 * Private constructor to aboid object creation from outside classes.
 *
 * @param context
 */
public DatabaseAccess(Context context) {
    this.openHelper = new DatabaseOpenHelper(context);
}

/**
 * Return a singleton instance of DatabaseAccess.
 *
 * @param context the Context
 * @return the instance of DabaseAccess
 */
public static DatabaseAccess getInstance(Context context) {
    if (instance == null) {
        instance = new DatabaseAccess(context);
    }
    return instance;
}

/**
 * Open the database connection.
 */
public void open() {
    this.database = openHelper.getWritableDatabase();
}

/**
 * Close the database connection.
 */
public void close() {
    if (database != null) {
        this.database.close();
    }
}

/**
 * Read all quotes from the database.
 *
 * @return a List of quotes
 */
public List<String> getQuotes() {
    List<String> list = new ArrayList<>();
    Cursor cursor = database.rawQuery("SELECT * FROM quotes", null);
    cursor.moveToFirst();
    while (!cursor.isAfterLast()) {
        list.add(cursor.getString(0));
        cursor.moveToNext();
    }
    cursor.close();
    return list;
}
public Cursor getRProgram() {
    Cursor mCursor= database.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_NAME},null,null,null,null,"RANDOM()");
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;

}

}

这是我的MainActivity

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.List;

import android.os.Bundle;
 import android.support.v7.app.ActionBarActivity;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.List;
import android.database.Cursor;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

private ListView listView;


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

    Button generate = (Button) findViewById(R.id.Generate);
    generate.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            DatabaseAccess myDatabaseHelper = new    DatabaseAccess(MainActivity.this);
            myDatabaseHelper.open();
            Cursor d = myDatabaseHelper.getRProgram();
            if (d.moveToFirst()) ;
            DisplayProgram(d);
            myDatabaseHelper.close();

        }

        public void DisplayProgram(Cursor d) {
            TextView result2 = (TextView) findViewById(R.id.result2);
            result2.setText("\n" + d.getString(1));
        }
    });
}
}

Answer 1

以下是从15到0的倒计时示例。您可以获得所需的值并将其传递到我使用15000（毫秒）的地方

 public class YourClass extends Activity {

        TextView textView;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_home);
            textView = (TextView) findViewById(R.id.text);

            // 15000 is the starting number (in milliseconds)
            // 1000 is the number to count down each time (in milliseconds)
            MyCount counter = new MyCount(15000, 1000); // PASS YOUR VALUE INSTEAD  15000 Here
            counter.start();
        }


        // count down timer is an abstract class, so extend it and fill in methods
        public class MyCount extends CountDownTimer {

            public MyCount(long millisInFuture, long countDownInterval) {
                super(millisInFuture, countDownInterval);
            }

            @Override
            public void onFinish() {
                // it's done
                textView.setText("Done!");
            }

            @Override
            public void onTick(long millisUntilFinished) {
                textView.setText("Left: " + millisUntilFinished / 1000);
            }
        }
    }

从数据库中的值创建Coutdown Timer

1 个答案: