java - SQLite 数据库读取初始化

Question

这是我使用 Eclipse 构建的 Android 应用程序。我有一个小问题是 brojac 的值不会更改为 5，它保持初始化状态。我不知道问题是什么，甚至不知道要尝试什么。无论如何谢谢!

这里是sql数据库代码:

package com.peky.smartornot;

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

public class Sql {
    public static final String KEY_ROWID= "_id";
    public static final String KEY_JOKERS= "joker";
    public static final String KEY_JOKERAMMOUNT= "ammount";

    private static final String DATABASE_NAME= "SQL";
    private static final String DATABASE_TABLE= "peoples_table";
    private static final int DATABASE_VERSION= 1;

    private DbHelper ourHelper;
    private final Context ourContext;
    private SQLiteDatabase ourDatabase;


    private static class DbHelper extends SQLiteOpenHelper{

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

        @Override
        public void onCreate(SQLiteDatabase db) {
            // TODO Auto-generated method stub
            db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
                    KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                    KEY_JOKERS + " INTEGER, " + 
                    KEY_JOKERAMMOUNT + " INTEGER);"
                    );

        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            // TODO Auto-generated method stub
            db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
            onCreate(db);
        }

    }

    public Sql(Context c){
        ourContext=c;
    }
    public Sql open(){
        ourHelper = new DbHelper(ourContext);
        ourDatabase=ourHelper.getWritableDatabase();
        return this;
    }
    public void close(){
        ourHelper.close();
    }
    public long spremi(int brojjokera, int kolicina) {
        // TODO Auto-generated method stub
        ContentValues cv = new ContentValues();
        cv.put(KEY_JOKERS, brojjokera);
        cv.put(KEY_JOKERAMMOUNT, kolicina);
        return ourDatabase.insert(DATABASE_TABLE, null, cv);

    }

    public int procitaj() {
        // TODO Auto-generated method stub
        String[] columns = new String[] { KEY_ROWID, KEY_JOKERS,
                KEY_JOKERAMMOUNT };
        Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null,
                null, null);
        int citac = 0;
        int iJoker = c.getColumnIndex(KEY_JOKERS);
        int iJokerammount = c.getColumnIndex(KEY_JOKERAMMOUNT);
        for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
            if (c.getInt(iJoker) == 1)
                citac = c.getInt(iJokerammount);
        }
        return citac;

    }
}

这里是函数:

package com.peky.smartornot;

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

public class Redeemcode extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_redeemcode);
    }

    public void provjeri(View view){
        EditText josip=(EditText)findViewById(R.id.test);
        TextView proba=(TextView)findViewById(R.id.povrat);
        String provjera=josip.toString();
        int kolicina=5,brojac=0;
        int brojjokera=1;
        Sql ulaz= new Sql(this);
        if (provjera=="josip"){
            ulaz.open();
            ulaz.spremi(brojjokera, kolicina);
            brojac= ulaz.procitaj();
            ulaz.close();

        }
        proba.setText(""+brojac);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.redeemcode, menu);
        return false;
    }
}

Answer 1

brojac= ulaz.procitaj() 未执行，因为 if 条件可能失败，因为您正在使用 == 来压缩字符串

您需要使用 .equals 比较字符串

if (provjera.equals("josip")){
        ulaz.open();
        ulaz.spremi(brojjokera, kolicina);
        brojac= ulaz.procitaj();
        proba.setText("Updated value is "+brojac);
        ulaz.close();

 }else
 {
         proba.setText("Old value is "+brojac);
 }