Question

我想在其上创建一个示例 SQLite 数据库和操作。

我能够 INSERT 数据进入表格。但我无法 RETRIEVE / SELECT 数据从db。

显示以下例外

05-09 12:19:26.163: W/dalvikvm(22638): threadid=1: thread exiting with uncaught 

exception (group=0x40015560)
05-09 12:19:26.183: E/AndroidRuntime(22638): FATAL EXCEPTION: main
05-09 12:19:26.183: E/AndroidRuntime(22638): java.lang.IllegalStateException: Could not execute method of the activity
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.view.View$1.onClick(View.java:2144)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.view.View.performClick(View.java:2485)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.view.View$PerformClick.run(View.java:9080)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.os.Handler.handleCallback(Handler.java:587)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.os.Handler.dispatchMessage(Handler.java:92)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.os.Looper.loop(Looper.java:123)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.app.ActivityThread.main(ActivityThread.java:3683)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at java.lang.reflect.Method.invokeNative(Native Method)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at java.lang.reflect.Method.invoke(Method.java:507)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at dalvik.system.NativeStart.main(Native Method)
05-09 12:19:26.183: E/AndroidRuntime(22638): Caused by: java.lang.reflect.InvocationTargetException
05-09 12:19:26.183: E/AndroidRuntime(22638):    at java.lang.reflect.Method.invokeNative(Native Method)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at java.lang.reflect.Method.invoke(Method.java:507)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.view.View$1.onClick(View.java:2139)
05-09 12:19:26.183: E/AndroidRuntime(22638):    ... 11 more
05-09 12:19:26.183: E/AndroidRuntime(22638): Caused by: android.database.sqlite.SQLiteException: no such table: MYTABLE: , while compiling: SELECT _id, name, password FROM MYTABLE
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteCompiledSql.compile(SQLiteCompiledSql.java:92)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:65)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:83)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:49)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:42)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1356)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1235)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1189)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1271)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at com.example.sqlite.MyDatabase.getDetails(MyDatabase.java:32)
05-09 12:19:26.183: E/AndroidRuntime(22638):    at com.example.sqlite.MainActivity.getDetails(MainActivity.java:43)
05-09 12:19:26.183: E/AndroidRuntime(22638):    ... 14 more

Android 中的代码添加在

下面

MainActivity.Java

package com.example.sqlite;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

MyDatabase myDataHelper;
EditText uid,pwd;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    uid = (EditText)findViewById(R.id.editText1);
    pwd = (EditText)findViewById(R.id.editText2);

    myDataHelper = new MyDatabase(this); 


}

public void addUser(View v)
{
    String username = uid.getText().toString();
    String password = pwd.getText().toString();

    long id = myDataHelper.insertData(username, password);
    if(id<0)
    {
        Toast.makeText(this, "Success", Toast.LENGTH_SHORT).show();
    }
    else
    {
        Toast.makeText(this, "Un Success", Toast.LENGTH_SHORT).show();
    }
}
public void getDetails(View v)
{
    String data = myDataHelper.getDetails();
    Toast.makeText(this,data, Toast.LENGTH_SHORT).show();

}


}

和

MyDatabase.java

package com.example.sqlite;

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

public class MyDatabase  {


myDataHelper helper;

public MyDatabase(Context context)
{
    helper = new myDataHelper(context);
}
public long insertData(String name, String pass){
    SQLiteDatabase db = helper.getWritableDatabase();
    ContentValues cv = new ContentValues();
    cv.put(myDataHelper.NAME, name);
    cv.put(myDataHelper.PASSWORD, pass);
    long id = db.insert(myDataHelper.TABLE_NAME, null, cv);
    db.close();
    return id;
}
public String getDetails()
{
    SQLiteDatabase db = helper.getWritableDatabase();
    String[] columns = {myDataHelper.UID,myDataHelper.NAME,myDataHelper.PASSWORD};
    Cursor cursor = db.query(myDataHelper.TABLE_NAME, columns, null, null, null, null, null);

    StringBuffer buff = new StringBuffer();
    while(cursor.moveToNext())
    {
        int cid = cursor.getInt(0);
        String name =  cursor.getString(1);
        String password = cursor.getString(2);
        buff.append(cid+ " "+name+" "+password);

    }

    return buff.toString();
}


 class myDataHelper extends SQLiteOpenHelper
{
    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "MYDATABASE";
    private static final String TABLE_NAME = "MYTABLE";
    private static final String UID = "_id";
    private static final String NAME = "name";
    private static final String PASSWORD = "password";
    private static final String CREATE_TABLE = "CREATE TABLE "+TABLE_NAME+
                                                " ("+UID+" INTEGER PRIMERY KEY AUTOINCREMENT,"
                                                    +NAME+" VARCHAR(225), " 
                                                    +PASSWORD+" VARCHAR(225));";
    private static final String DROP_TABLE = "DROP TABLE IF EXISTS "+"TABLE_NAME";    
    Context context;

    public myDataHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.context = context;
        Message("In Constructor");
    }



    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        try {
            db.execSQL(CREATE_TABLE);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
        Message("In OnCreate");

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVer, int newVer) {
        // TODO Auto-generated method stub
        try {
            db.execSQL(DROP_TABLE);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Message("In onUpgrade");


    }

    private void Message(String string) {
        // TODO Auto-generated method stub

        Toast.makeText(context, string, Toast.LENGTH_SHORT).show();

    }

}
}

Answer 1

我可以在你的代码中指出两件事。

如果出现问题，您将从onCreate打印堆栈曲目 - 您是否检查了它？
在onUpgrade你正在放弃这张桌子。我不确定原因是什么，但我会说您的onUpgrade方法应该根本不存在或者create table if not exists ...中包含{{1}}。

Answer 2

我能够将数据插入表

可能不是。你的吐司信息是相反的。 insert()会在失败时返回负值，并将其视为成功。

修复插入成功条件。
从数据库帮助程序中删除catch块。当出现问题时，生命周期回调onCreate()和onUpgrade()应该抛出。
卸载并重新安装您的应用，以便删除任何旧版本的数据库文件。

找不到表在SQLite中的异常

2 个答案: