安卓SQLiteOpenHelper:的onCreate()方法没有被调用。为什么?方法、SQLiteOpenHelper、onCreate

由网友(青橘栀耳)分享简介:我试图让我的第一个Android应用程序。我听说,如果没有创建数据库的SQLiteOpenHelper.onCreate()方法的过程创建表。然而,以为我试图调试的onCreate()方法没有奏效,甚至。请看看下面的code和给我任何建议。任何帮助将AP preciated。======================...

我试图让我的第一个Android应用程序。我听说,如果没有创建数据库的SQLiteOpenHelper.onCreate()方法的过程创建表。然而,以为我试图调试的onCreate()方法没有奏效,甚至。请看看下面的code和给我任何建议。任何帮助将AP preciated。

  ====================================== ===========================
公共类NameToPinyinActivity延伸活动{

    DatabaseOpenHelper帮手= NULL;

    @覆盖
    公共无效的onCreate(包savedInstanceState){
        super.onCreate(savedInstanceState);
        的setContentView(R.layout.nametopinyin);

        按钮searchButton =(按钮)findViewById(R.id.search);
        sea​​rchButton.setOnClickListener(新ButtonClickListener());

        辅助=新DatabaseOpenHelper(NameToPinyinActivity.this);
    }

================================================== ===============
公共类DatabaseOpenHelper扩展SQLiteOpenHelper {

    / ** DB名称* /
    私有静态最后弦乐DB_NAME =拼音;

    / ** CREATE TABLE SQL * /
    私有静态最后弦乐CREATE_TABLE_SQL =CREATE TABLE UNI code_PINYIN
            +(ID INTEGER PRIMARY KEY AUTOINCREMENT,
            +UNI code文本NOT NULL,拼音文字NOT NULL);

    公共DatabaseOpenHelper(上下文的背景下){
        超级(上下文,DB_NAME,空,1);
    }

    @覆盖
    公共无效的onCreate(SQLiteDatabase DB){
        db.beginTransaction();
        尝试 {
            db.execSQL(CREATE_TABLE_SQL);
            db.setTransactionSuccessful();
        }赶上(例外五){
            e.printStackTrace();
        } 最后 {
            db.endTransaction();
        }
    }

================================================== ===============
 

解决方案

我也有过与 SQLiteOpenHelper 的麻烦。什么工作对我来说是存储成员变量

  SQLiteDatabase分贝;
 

在SQLiteOpenHelper的子类,并要求

  DB = getWritableDatabase();
 
华为,加油 他们都宣布封杀华为,却遭到网络大混乱

在构造函数中。

在回答这个问题还包括有用的信息:SQLiteOpenHelper不能打电话的onCreate?

我希望这有助于!

I am trying to make my first android app. I heard that the SQLiteOpenHelper.onCreate() method process to create tables if the database is not created. However, the onCreate() method did not work even thought I tried to debug. Please look at the code below and give me any suggestions. Any help will be appreciated.

=================================================================
public class NameToPinyinActivity extends Activity {

    DatabaseOpenHelper helper = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.nametopinyin);

        Button searchButton = (Button) findViewById(R.id.search);
        searchButton.setOnClickListener(new ButtonClickListener());

        helper = new DatabaseOpenHelper(NameToPinyinActivity.this);
    }

=================================================================
public class DatabaseOpenHelper extends SQLiteOpenHelper {

    /** DB Name */
    private static final String DB_NAME = "pinyin";

    /** CREATE TABLE SQL */
    private static final String CREATE_TABLE_SQL = "CREATE TABLE UNICODE_PINYIN"
            + "(ID INTEGER PRIMARY KEY AUTOINCREMENT, "
            + "UNICODE TEXT NOT NULL, PINYIN TEXT NOT NULL)";

    public DatabaseOpenHelper(Context context) {
        super(context, DB_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.beginTransaction();
        try {
            db.execSQL(CREATE_TABLE_SQL);
            db.setTransactionSuccessful();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            db.endTransaction();
        }
    }

=================================================================

解决方案

I have also had trouble with the SQLiteOpenHelper. What worked for me was storing a member variable

SQLiteDatabase db;

In the SQLiteOpenHelper subclass and calling

 db = getWritableDatabase();

in the constructor.

The answer to this question also includes helpful information: SQLiteOpenHelper failing to call onCreate?

I hope this helps!

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