0

データベースのデータを更新したいのですが、sqldb.update 行で java.lang.NullPointerException が発生します ... データの更新方法を検索しましたが、それでも同じです。間違いを教えてください

ここに content.java の一部

    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;
    }
}

ここに mydb.java があります

    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;
    }
}

ここで丸太猫

    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 に答える 3

0

データベースからデータを更新または選択するmydb代わりに 使用します。これは、挿入、更新、または選択などのデータベース操作を行うためにクラスを拡張しているクラスのオブジェクトであるためです。そのため、インスタンスの代わりにインスタンスを使用してすべての操作を実行する必要がありますsqldbmydbSQLiteAssetHelperMyDBSQLiteDatabase

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 に答える
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 に答える
0

Variable を初期化していないと思いますSQLiteDatabase sqldb。あなたはそれを宣言しましたが、あなたがそれを初期化した場所はどこにもありません。多分それがあなたが行に NUllPointer を取得している理由です sqldb.update("populer", cv, "_id ?", new String[]{id});

于 2012-12-14T06:42:28.110 に答える