Question

自从一周以来我一直在努力从数据库填充android中的listview但是遇到大问题请我很高兴如果有人会帮助这里是ma代码 // databasehelper class

package com.example;

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

public class DatabaseHelper extends SQLiteOpenHelper{
 public static final String DBNAME = "company.db";    
  public static final String ENAME="ename";
  public static final String ADD="addr";
  public static final String PNO="pno";
  public static final String FA="fa";
  public static final String tablename="company";


  public DatabaseHelper(Context context) {
        super(context, DBNAME, null, 1);
        // TODO Auto-generated constructor stub
    }
@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL("CREATE TABLE company (_ID INTEGER PRIMARY KEY AUTOINCREMENT,ename TEXT,addr TEXT,pno TEXT,fa TEXT);");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
    db.execSQL("DROP IF TABLE EXISTS company");
    onCreate(db);
}
}

//这里是我试图填充listview的类 package com.example;

import java.util.ArrayList;

import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class Text extends ListActivity {
private ArrayList<String> results = new ArrayList<String>();
private String tableName = DatabaseHelper.tablename;
private SQLiteDatabase newDB;

@Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);

       openAndQueryDatabase();

        displayResultList();
}

private void displayResultList() {
    // TODO Auto-generated method stub
    TextView tView = new TextView(this);
    tView.setText("This data is retrieved from the database and only 4 " +
            "of the results are displayed");
    getListView().addHeaderView(tView);

    setListAdapter(new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_2, results));
    getListView().setTextFilterEnabled(true);
}

private void openAndQueryDatabase() {
    // TODO Auto-generated method stub
    try {
DatabaseHelper dbHelper = new     DatabaseHelper(this.getApplicationContext());

        newDB = dbHelper.getWritableDatabase();
        Cursor c = newDB.rawQuery("SELECT ENAME, PNO  FROM " +
                tableName, null);

        if (c != null ) {
            if  (c.moveToFirst()) {
                do {
                    String ename = c.getString(c.getColumnIndex("ENAME"));
                    String addr = c.getString(c.getColumnIndex("PNO"));
                    results.add("Name: " + ename + ",Age: " + addr);
                }while (c.moveToNext());
            } 
        }           
    } catch (SQLiteException se ) {
        Log.e(getClass().getSimpleName(), "Could not create or Open the database");
    } finally {
        if (newDB != null) 
            newDB.execSQL("DELETE FROM " + tableName);
            newDB.close();
    }

}
}

Answer 1

您不会在数据库中添加任何内容。您没有进行任何insert调用来填充数据库。因此，当您执行查询时，您将获得一个空光标。因此，results没有添加任何内容。这就是为什么你的listview是空的。

没有得到：从android中的SQLITE数据库填充listview

1 个答案: