原因：找不到com.example.exampleCombant.Appname.Database：com / Database.class中找到com.example.example.appname.DataBase

Question

我無法運行我的應用程序由於這個問題，我已經使用SQL lite Open Helper創建了一個SQL lite數據庫並添加了我需要的表，但是我無法運行該應用程序嗎？ 我必須在周日完成應用程序才能將其發送給我的老師。 我試圖從測試設備中刪除該應用程序並重新安裝，並檢查了我的應用程序文件，但未找到任何內容

package com.mohnad.theeducationnewera.marksbook;

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

public class DataBase extends SQLiteOpenHelper {
    private static final String database_name = "DB";
    private static final int database_vesion =1;
    private static final String UID = "id";
    private static final String name = "Name";
    private static final String work_mark = "Works Mark";
    private static final String test_mark = "Tests mark";
    private static final String tableName = "Students";
    private Context context;
    private static final String DROP_TABLE = "DROP TABLE IF EXISTS " +tableName;
    private static final String CREATE_TABLE = "CREATE TABLE " +tableName+" " +
        " ("+UID+" INTEGER PRIMARY KEY AUTOINCREMENT," +
        " "+name+" TEXT VARCHAR(255))," +
        " "+work_mark+" INTEGER ," +
        " "+test_mark+" INTEGER ;";

    public DataBase(Context context) {
        super(context, database_name,null, database_vesion);
    }

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

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

Answer 1

首先，您必須確保清單中只有一個發射器

        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>

DBHelper中的第二名

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

運行好運后給我反饋