Question

我正在尝试使用SQLite创建数据库，但出现此错误。我不知道原因。

这是我的代码：

MainActivity.java。

import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    private final String TAG = "de.lecture.hska";
    EditText et_Name, et_Age;

    MySQLiteOpenHelper mySQLiteOpenHelper;
    MySQLAdapter mySQLAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et_Name = (EditText) findViewById(R.id.Name);
        et_Age = (EditText) findViewById(R.id.Age);

        mySQLAdapter = new MySQLAdapter(this);
    }

    public void addData(View view) {
        //SQLiteDatabase db = mySQLiteOpenHelper.getWritableDatabase();

        String tmp = et_Name.getText().toString();
        long ok = mySQLAdapter.addMyData(tmp);

        Toast.makeText(this, String.valueOf(ok), Toast.LENGTH_LONG).show();
    }


    public void viewAllData (View view){
        String tmp = mySQLAdapter.showAll();
        Toast.makeText(this, tmp, Toast.LENGTH_LONG).show();
    }
}

MySQLAdapter：

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.util.Log;
import android.widget.Toast;

/**
 * Created by caju1013 on 09.12.2015.
 */

public class MySQLAdapter {
    MySQLiteOpenHelper mySQLiteOpenHelper;

    MySQLAdapter(Context context) {
        mySQLiteOpenHelper = new MySQLiteOpenHelper(context);
    }

    public long addMyData (String Name){
        ContentValues cv = new ContentValues();
        cv.put(MySQLiteOpenHelper.TABLECOLUMN_NAME, "Probandoooo");

        SQLiteDatabase db = mySQLiteOpenHelper.getWritableDatabase();

        return db.insert(MySQLiteOpenHelper.TABLE_NAME, null, cv);
    }

    public String showAll(){
        SQLiteDatabase db = mySQLiteOpenHelper.getWritableDatabase();
        String [] array = {"Name"};

        Cursor cursor = db.query(MySQLiteOpenHelper.TABLE_NAME, null, MySQLiteOpenHelper.TABLECOLUMN_NAME+" = Name", null, null, null, null);

        db.close();

        int index = cursor.getColumnIndex(MySQLiteOpenHelper.TABLECOLUMN_NAME);
        StringBuffer stringBuffer = new StringBuffer();

        while (cursor.moveToNext()) {
            String tempo = cursor.getString(index);
            stringBuffer.append(tempo+"\n");
        }

        return stringBuffer.toString();
    }

    public class MySQLiteOpenHelper extends SQLiteOpenHelper {
        private final static String TAG = "de.lecture.hska";
        private final static String DATABASE_NAME = "mydatabase.db";
        private final static int DATABASE_VERSION = 1;

        private final static String TABLE_NAME = "MYTABLE";
        private final static String TABLECOLUMN_UID = "_id";
        private final static String TABLECOLUMN_NAME = "Name";
        private final static String TABLECOLUMN_AGE = "Age";

        private final static String CREATETABLE = "CREATE TABLE " + TABLE_NAME + "(" + TABLECOLUMN_UID + " INTEGER PRIMARY KEY AUTOINCREMENT , " + TABLECOLUMN_NAME + " VARCHAR(255), " + TABLECOLUMN_AGE + " VARCHAR(255));";

        private final static String DROPTABLE = "DROP TABLE IF EXIST " + TABLE_NAME;
        private Context mycontext;

        public MySQLiteOpenHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);

            this.mycontext = context;
            Toast.makeText(mycontext, "constructor called",Toast.LENGTH_LONG).show();
            Log.i(TAG, "Constructor called");
        }

        public void onCreate(SQLiteDatabase sqLiteDatabase) {
            try {
                sqLiteDatabase.execSQL(CREATETABLE);
                Toast.makeText(mycontext, "onCreate",Toast.LENGTH_LONG).show();
                Log.i(TAG, "onCreate");
            } catch (SQLException e) {
                Toast.makeText(mycontext, e.toString(),Toast.LENGTH_LONG).show();
                Log.i(TAG, Log.getStackTraceString(e));
            }
        }

        public void onUpgrade (SQLiteDatabase sqLiteDatabase, int i, int i1){
            try {
                sqLiteDatabase.execSQL(DROPTABLE);
                onCreate(sqLiteDatabase);
                Toast.makeText(mycontext, "OnUpgrade",Toast.LENGTH_LONG).show();
                Log.i(TAG, "onUpgrade");
            } catch (SQLException e) {
                Toast.makeText(mycontext, e.toString(),Toast.LENGTH_LONG).show();
                Log.i(TAG, Log.getStackTraceString(e));
            }
        }
    }
}

MySQLiteOpenHelper：

import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;

/**
 * Created by caju1013 on 09.12.2015.
 */
class MySQLiteOpenHelper extends SQLiteOpenHelper {
    private final static String TAG = "de.lecture.hska";
    private final static String DATABASE_NAME = "mydatabase.db";
    private final static int DATABASE_VERSION = 1;

    private final static String TABLE_NAME = "MYTABLE";
    private final static String TABLECOLUMN_UID = "_id";
    private final static String TABLECOLUMN_NAME = "Name";
    private final static String TABLECOLUMN_AGE = "Age";

    private final static String CREATETABLE = "CREATE TABLE " + TABLE_NAME + "(" + TABLECOLUMN_UID + " INTEGER PRIMARY KEY, " + TABLECOLUMN_NAME + " VARCHAR(255), " + TABLECOLUMN_AGE + " VARCHAR(255));";
    private final static String DROPTABLE = "DROP TABLE IF EXIST " + TABLE_NAME;
    private Context mycontext;

    public MySQLiteOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.mycontext = context;
        Toast.makeText(mycontext, "constructor called",Toast.LENGTH_LONG).show();
        Log.i(TAG, "Constructor called");
    }

    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        try {
            sqLiteDatabase.execSQL(CREATETABLE);
            Toast.makeText(mycontext, "onCreate",Toast.LENGTH_LONG).show();
            Log.i(TAG, "onCreate");
        } catch (SQLException e) {
            Toast.makeText(mycontext, e.toString(),Toast.LENGTH_LONG).show();
            Log.i(TAG, Log.getStackTraceString(e));
        }
    }

    public void onUpgrade (SQLiteDatabase sqLiteDatabase, int i, int i1){
        try {
            sqLiteDatabase.execSQL(DROPTABLE);
            onCreate(sqLiteDatabase);
            Toast.makeText(mycontext, "OnUpgrade",Toast.LENGTH_LONG).show();
            Log.i(TAG, "onUpgrade");
        } catch (SQLException e) {
            Toast.makeText(mycontext, e.toString(),Toast.LENGTH_LONG).show();
            Log.i(TAG, Log.getStackTraceString(e));
        }
    }

}

activity_main.xml中：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Name"
        android:id="@+id/Name"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Age"
        android:id="@+id/Age"
        android:layout_below="@+id/Name"
        android:layout_alignStart="@+id/Name"
        android:layout_marginTop="64dp" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Add Data"
        android:id="@+id/button"
        android:layout_below="@+id/Name"
        android:layout_centerHorizontal="true"
        android:onClick="addData"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="View all data"
        android:id="@+id/button2"
        android:layout_below="@+id/Age"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="37dp"
        android:onClick="viewAllData"/>
</RelativeLayout>

Answer 1

你在这一行中的问题::

private final static String CREATETABLE = "CREATE TABLE " + TABLE_NAME + "(" + TABLECOLUMN_UID + " INTEGER PRIMARY KEY, " + TABLECOLUMN_NAME + " VARCHAR(255), " + TABLECOLUMN_AGE + " VARCHAR(255));";

因为SQLITE不支持varchar将其更改为TEXT而不需要定义长度。

应该是这样的：

private final static String CREATETABLE = "CREATE TABLE " + TABLE_NAME + "(" + TABLECOLUMN_UID + " INTEGER PRIMARY KEY, " + TABLECOLUMN_NAME + " TEXT, " + TABLECOLUMN_AGE + " TEXT);";

为什么Logcat显示“没有这样的表：MYTABLE（代码1）”

1 个答案: