Question

我在libGdx中使用数据库时遇到问题，首先我要创建这个类：

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DataBaseHelper extends SQLiteOpenHelper {

public DataBaseHelper(Context context, String name,CursorFactory factory, int version)
{
    super(context, name, factory, version);
}

@Override
public void onCreate(SQLiteDatabase _db)
{
    _db.execSQL(DataBaseClass.DATABASE_RECORD);

}

@Override
public void onUpgrade(SQLiteDatabase _db, int _oldVersion, int _newVersion)
{

    Log.w("TaskDBAdapter", "Upgrading from version " +_oldVersion + " to " +_newVersion + ", which will destroy all old data");

    onCreate(_db);
}
}

和这堂课：

import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.Collections;

public class DataBaseClass {

static final String DATABASE_NAME = "my.database";
static final int DATABASE_VERSION = 1;
public static final int NAME_COLUMN = 1;

static final String DATABASE_RECORD = "create table "+"RECORD"+
        "( " + "SCORE text, GAMES_PLAYED text); ";

public  SQLiteDatabase db;

private final Context context;

private DataBaseHelper dbHelper;


public DataBaseClass(Context _context) {
    context = _context;
    dbHelper = new DataBaseHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
}

public DataBaseClass open() throws SQLException {
    db = dbHelper.getWritableDatabase();
    return this;
}

public void close() {
    db.close();
}

public  SQLiteDatabase getDatabaseInstance() {
    return db;
}




public void updateGamesPlayed(String game) {

    ContentValues updatedValues = new ContentValues();

    updatedValues.put("GAMES_PLAYED", game);

    String where="GAMES_PLAYED = ?";
    db.update("RECORD",updatedValues, where, new String[]{game});
}


public void updateBestScore(String score) {

    ContentValues updatedValues = new ContentValues();

    updatedValues.put("SCORE", score);

    String where="SCORE = ?";
    db.update("RECORD",updatedValues, where, new String[]{score});
}
}

但是当我在实现界面屏幕的我的主要类中调用DataBaseClass时，我遇到了问题：

DBClass = new DataBaseClass(CONTEXT);

这堂课的背景是什么？我尝试使用：＆＃34;这＆＃34;，＆＃34; getContext（）＆＃34;，getActivity＆＃34;，＆＃34; this.getActivity＆＃34;等...但没有任何作用。

有人可以帮助我吗？

Answer 1

这里的上下文指的是您当前的类上下文，您只需传递this或principal.this

如何在实现Screen的类中使用上下文？

1 个答案: