我在用一个简单的文件创建sqlite db时遇到了问题。我正在记录一些消息,如果创建或升级了数据库,我希望在日志中显示这些消息,但它们没有显示。
代码如下:
package com.example.karim.myandoidapp;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class HomeActivity extends AppCompatActivity {
String msg = "My android app log : ";
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.e(msg, "onCreate() event loading activity_home view");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Log.e(msg, "onCreate() event loading activity_home view");
Context context = myandoidapp.getAppContext();
MySQLiteHelper MySQLiteHelper = new MySQLiteHelper(context);
}
private class MySQLiteHelper extends SQLiteOpenHelper {
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "mydbnamesss";
public MySQLiteHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.e("DEBUG: ", "db created at " + db.getPath());
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.e("DEBUG: ", "db upgraded ");
}
}
}
以下是我的日志中的输出:
06-14 15:02:29.122 6644-6644/com.example.karim.myandoidapp E/My android app log :: Opening HomeActivity
--------- beginning of system
06-14 15:02:29.141 6644-6644/com.example.karim.myandoidapp E/My android app log :: onCreate() event loading activity_home view
06-14 15:02:29.203 6644-6673/com.example.karim.myandoidapp D/EGL_emulation: eglMakeCurrent: 0xa22050c0: ver 3 0 (tinfo 0xa2203360)
06-14 15:02:29.209 6644-6673/com.example.karim.myandoidapp D/EGL_emulation: eglMakeCurrent: 0xa22050c0: ver 3 0 (tinfo 0xa2203360)
06-14 15:02:29.216 6644-6673/com.example.karim.myandoidapp D/EGL_emulation: eglMakeCurrent: 0xa22050c0: ver 3 0 (tinfo 0xa2203360)
06-14 15:02:29.218 6644-6673/com.example.karim.myandoidapp D/OpenGLRenderer: endAllActiveAnimators on 0x8eeae180 (RippleDrawable) with handle 0xa2203ac0
我在这里添加了我是如何获取上下文的,以防它相关:
打包com.example.karim.myandoidapp;
导入android.content.Context;导入android.app.Application;
public class myandoidapp extends Application {
private static Context context;
public void onCreate() {
super.onCreate();
myandoidapp.context = getApplicationContext();
}
public static Context getAppContext() {
return myandoidapp.context;
}
}
谢谢
发布于 2018-06-15 06:13:03
您的代码定义了SQLiteOpenHelper
的一个子类,然后实例化它,但这还不足以创建/打开SQLite数据库。如果我是你,我会读一读谷歌开发的名为Room的新库。这是一个非常棒的库,可以帮助您轻松创建和维护SQLite数据库,而不是手动创建自己的SQLiteOpenHelper
实例、维护迁移等。
https://stackoverflow.com/questions/50866579
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