Question

我已经编写了这段代码，通过使用“for”循环在数据库中插入数据，我也希望看到数据库的数据，但是应用程序崩溃了。我找不到它的问题请帮帮我... < / p>

package com.smshah.database;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;


public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    TextView t1=(TextView)findViewById(R.id.textView1);
    TextView t2=(TextView)findViewById(R.id.textView2);
    TextView t3=(TextView)findViewById(R.id.textView3);

    SQLiteDatabase db = openOrCreateDatabase("mapdb", MODE_PRIVATE, null);
    db.execSQL("CREATE TABLE IF NOT EXISTS maptb (rssi INT(4),xval INT(4),yval INT(4));");
    int x=0;
    int y=0;
    int r=0;

    for (int i = 0; i <= 100; i++) 
    {
        db.execSQL("INSERT INTO maptb VALUES("+r+","+x+","+y+");");
        x = x + 1;
        r = r - 1;
    }

    Cursor resultSet = db.rawQuery("Select * from maptb",null);
    resultSet.moveToFirst();
    int rssi = resultSet.getInt(resultSet.getColumnIndex("rssi"));
    int xval = resultSet.getInt(resultSet.getColumnIndex("xval"));
    int yval = resultSet.getInt(resultSet.getColumnIndex("yval"));

    t1.setText(rssi);
    t2.setText(xval);
    t3.setText(yval);

    db.close();
}

}

logcat的

08-04 03:12:17.842: W/ResourceType(13662): No package identifier when getting value for resource number 0x00000000
08-04 03:12:17.852: D/AndroidRuntime(13662): Shutting down VM
08-04 03:12:17.852: W/dalvikvm(13662): threadid=1: thread exiting with uncaught exception (group=0x40c0ea68)
08-04 03:12:17.882: E/AndroidRuntime(13662): FATAL EXCEPTION: main
08-04 03:12:17.882: E/AndroidRuntime(13662): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.smshah.database/com.smshah.database.MainActivity}: android.content.res.Resources$NotFoundException: String resource ID #0x0
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1970)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.ActivityThread.access$600(ActivityThread.java:128)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.os.Looper.loop(Looper.java:137)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.ActivityThread.main(ActivityThread.java:4517)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at java.lang.reflect.Method.invokeNative(Native Method)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at java.lang.reflect.Method.invoke(Method.java:511)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at dalvik.system.NativeStart.main(Native Method)
08-04 03:12:17.882: E/AndroidRuntime(13662): Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x0
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.content.res.Resources.getText(Resources.java:260)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.widget.TextView.setText(TextView.java:3680)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at com.smshah.database.MainActivity.onCreate(MainActivity.java:47)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.Activity.performCreate(Activity.java:4470)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1053)
08-04 03:12:17.882: E/AndroidRuntime(13662):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1934)
08-04 03:12:17.882: E/AndroidRuntime(13662):

Answer 1

您的崩溃似乎与数据库没有任何关系。它说没有找到资源异常。你能指出MainActivity第47行的内容吗？您应该设置TextView的内容。

修改

您要推送到TextView的是int，文本视图假定这些值是资源标识符而不是字符串。因此，请按照以下步骤使TextViews写入字符串而不是资源标识符。

t1.setText(rssi + ""); t2.setText(xval + ""); t3.setText(yval + "");

Answer 2

尝试创建查询功能，不同于 rawQuery ，它更容易阅读。

    //return false if something goes wrong
 public boolean add(int x, int y, int z) { 

    database = connection.getWritableDatabase();

      ContentValues values = new ContentValues();

      values.put(SQLConnection.COLUMN_X, x);
      values.put(SQLConnection.COLUMN_Y, y);
      values.put(SQLConnection.COLUMN_Z, z);

      return database.insert(SQLConnection.TABLE_MAPXYZ, null, values) != -1 ? true : false;
 }

也读过，试着：

public List<MapXYZ> getAll() {
        List<MapXYZ> mapList = new ArrayList<MapXYZ>();
        database = connection.getReadableDatabase();

        Cursor cursor = database.query(SQLConnection.TABLE_MAPXYZ, GET_ALL, null, null, null, null, null, null);

        if (cursor == null) //something goes wrong
            return null;

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                MapXYZ linemap = new MapXYZ();
                linemap.setX(cursor.getInt(0));
                linemap.setY(cursor.getInt(1));
                linemap.setZ(cursor.getInt(2));

                // Adding line to the list
                mapList.add(linemap);
            } while (cursor.moveToNext());
        }
        return mapList;
    }

一些提示：创建最终变量，不要错过表和列名称...... 有关Android Sqlite query reference

的更多信息，请参阅

PS：我没有测试这段代码，我自己使用并重命名变量

如何在android中插入和获取sqlite数据库中的数据？

2 个答案: