0

我想更新数据库中的数据，但它在 sqldb.update 行中给出 java.lang.NullPointerException ...我已经搜索了如何更新数据但它仍然相同，请告诉我错误

这里有一些 content.java

    package ta.ens;

import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Typeface;
import android.os.Bundle;
import android.text.ClipboardManager;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class Content extends Activity {
    /** Called when the activity is first created. */
    //TextView judul,hadits,arti; 
    ListView content;
    SimpleCursorAdapter adapter;
    MyDB mydb;
    Cursor cursor,populer;
    TextView judul,hadits,arti;
    SQLiteDatabase sqldb;
    Context context=this;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.custom_list_hadits);       
        mydb = new MyDB(this);

        judul = (TextView)findViewById(R.id.textjudul);
        hadits = (TextView)findViewById(R.id.texthadits);
        arti = (TextView)findViewById(R.id.textarti);

        Bundle extras = getIntent().getExtras();
        String id = extras.getString("row");
        String namajudul = extras.getString("rowjudul");                
        ContentValues cv = new ContentValues();
        populer = mydb.getPopularity(id);
        int jumlah = populer.getCount();
        if (jumlah == 0){
            cv.put("totalquery", 1);
            sqldb.update("populer", cv, "_id ?", new String[]{id});
        }else {
            jumlah = jumlah + 1;
            cv.put("totalquery", jumlah);
            sqldb.rawQuery("UPDATE populer SET totalquery = "+jumlah+" WHERE _id =" +id, null);
        }

        judul.setText(namajudul);
        hadits.setTypeface(Typeface.createFromAsset(getAssets(), "dejavusans.ttf"));
        cursor = mydb.getHadits(id);
        int total = cursor.getCount();
        for(int i = 1;i<=total;i++){
            String isihadits = ArabicUtilities.reshape(cursor.getString(cursor.getColumnIndex("hadits")));
            String isiarti = cursor.getString(cursor.getColumnIndex("arti"));
            hadits.setText(isihadits);
            arti.setText(isiarti);
            cursor.moveToNext();
        } 
        hadits.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                ClipboardManager clipboard = (ClipboardManager)getSystemService(CLIPBOARD_SERVICE);
                clipboard.setText(hadits.getText());
                Toast.makeText(context, "Copied to clipboard", Toast.LENGTH_SHORT).show();
            }
        });

        arti.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                ClipboardManager clipboard = (ClipboardManager)getSystemService(CLIPBOARD_SERVICE);
                clipboard.setText(arti.getText());
                Toast.makeText(context, "Copied to clipboard", Toast.LENGTH_SHORT).show();
            }
        });        
    }

     public boolean onCreateOptionsMenu(Menu menu){
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menuhelp, menu);
        return true;

    }

    public boolean onOptionsItemSelected(MenuItem item){
        Intent intent = new Intent();
        switch(item.getItemId()){
        case R.id.helptema :
            finish();
            intent.setClass(Content.this, Tema.class);
            startActivity(intent);
            break;
        case R.id.searchhelp :
            finish();
            intent.setClass(Content.this, Cari.class);
            startActivity(intent);
            break;
        case R.id.tentanghelp :
            finish();
            intent.setClass(Content.this, Tentang.class);
            startActivity(intent);
            break;
        case R.id.quithelp :
            finish();
            System.exit(0);
        }
        return true;
    }
}

这是 mydb.java

    package ta.ens;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import com.readystatesoftware.sqliteasset.SQLiteAssetHelper;

public class MyDB extends SQLiteAssetHelper{

    private static final String DATABASE_NAME = "hadits";
    private static final int DATABASE_VERSION = 1;

    public MyDB(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }

    public Cursor getAllTema(){
        SQLiteDatabase sqldb = getReadableDatabase();

        Cursor c = sqldb.rawQuery("SELECT * FROM tema", null);

        c.moveToFirst();
        return c;
    }

    public Cursor getJudul(String id){
        SQLiteDatabase sqldb = getReadableDatabase();

        Cursor jdl = sqldb.rawQuery("SELECT judul._id,judul.judul FROM judul,tema,temajudul WHERE tema._id = temajudul.idtema AND judul._id = temajudul.idjudul AND tema._id = "+id, null);
        jdl.moveToFirst();
        return jdl;
    }

    public Cursor getHadits(String id){
        SQLiteDatabase sqldb = getReadableDatabase();

        Cursor hadits = sqldb.rawQuery("SELECT hadits.hadits , hadits.arti FROM hadits,judul,judulhadits WHERE judul._id = judulhadits.idjudul AND hadits.rowid = judulhadits.idhadits AND judul._id = "+id, null);
        hadits.moveToFirst();
        return hadits;
    }

    public void virtualtabel(){
        SQLiteDatabase sqldb = getReadableDatabase();
        sqldb.execSQL("INSERT INTO virtualhadits SELECT * FROM hadits");
    }

    public Cursor getAllHadits(){
        SQLiteDatabase sqldb = getReadableDatabase();
        Cursor allcontent = sqldb.rawQuery("SELECT * FROM virtualhadits", null);
        return allcontent;
    }

    public Cursor getCari(String key){
        SQLiteDatabase sqldb = getReadableDatabase();       

        Cursor cari = sqldb.rawQuery("SELECT virtualhadits.rowid AS _id , judul.judul FROM judul,judulhadits,virtualhadits WHERE judul._id = judulhadits.idjudul AND virtualhadits.rowid = judulhadits.idhadits AND virtualhadits MATCH '"+key+"'",
                    null);
        cari.moveToFirst();
        return cari;
    }

    public Cursor getPopularity(String id){
        SQLiteDatabase sqldb = getReadableDatabase();

        Cursor semua = sqldb.rawQuery("SELECT totalquery FROM populer WHERE _id = "+id, null);
        return semua;
    }

    public Cursor getPopularitasJudul(){
        SQLiteDatabase sqldb = getReadableDatabase();

        Cursor populerjudul = sqldb.rawQuery("SELECT judul._id  judul.judul FROM judul,hadits,populer WHERE judul._id = judulhadits.idjudul AND hadits._id = judulhadits.idhadits AND populer._id = hadits._id ORDER BY populer.totalquery DESC", null);

        return populerjudul;
    }
}

这里日志猫

    12-14 13:28:02.821: ERROR/AndroidRuntime(5867): FATAL EXCEPTION: main
12-14 13:28:02.821: ERROR/AndroidRuntime(5867): java.lang.RuntimeException: Unable to start activity ComponentInfo{ta.ens/ta.ens.Content}: java.lang.NullPointerException
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.os.Looper.loop(Looper.java:123)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.app.ActivityThread.main(ActivityThread.java:4627)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at java.lang.reflect.Method.invokeNative(Native Method)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at java.lang.reflect.Method.invoke(Method.java:521)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at dalvik.system.NativeStart.main(Native Method)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867): Caused by: java.lang.NullPointerException
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at ta.ens.Content.onCreate(Content.java:54)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
12-14 13:28:02.821: ERROR/AndroidRuntime(5867):     ... 11 more
4

3 回答 3

0 
Better to use:

if (jumlah == 0){
            cv.put("totalquery", 1);
sqldb=Mydb.getWritableDatabase();
            sqldb.execSQL("update populer set _id=id");
        }
于 2013-08-27T06:48:37.800 回答
0

使用mydb而不是 sqldb用于更新或从数据库中选择数据，因为mydb它是一个类的对象，您在其中扩展SQLiteAssetHelper类以进行数据库操作，如插入、更新或选择。所以需要使用MyDB实例来执行所有操作而不是SQLiteDatabase实例

if (jumlah == 0){
        cv.put("totalquery", 1);
        mydb.update("populer", cv, "_id ?", new String[]{id});
    }else {
        jumlah = jumlah + 1;
        cv.put("totalquery", jumlah);
        mydb.rawQuery("UPDATE populer SET totalquery = 
                         "+jumlah+" WHERE _id =" +id, null);
    }
于 2012-12-14T06:50:24.820 回答
0

我认为您尚未初始化 Variable SQLiteDatabase sqldb。你已经声明了它，但我没有看到你初始化它的任何地方。也许这就是您获得 NUllPointer 的原因 sqldb.update("populer", cv, "_id ?", new String[]{id});

于 2012-12-14T06:42:28.110 回答