Question

这可能会成为一个蹩脚的问题，但我是初学者，似乎并不了解我的应用的行为。

我有一个SQLite数据库，以及主要活动中的列表视图。在列表视图中，我显示列表编号（行ID）和其他详细信息。在按下列表项时，会打开一个新活动，在文本视图中显示详细信息，并有2个图像按钮用于删除和同步。

该应用程序正常工作，直到我删除任何条目。

删除任何条目后，listview上的行ID似乎不会更新行号。（如果我删除第一行，则顶部的行显示为2（应为1，因为它是新的第一行）。

然而，当我显示记录的细节时，它出来是正确的。（列表中的第二项显示行号2）

此外，当我按下列表视图中的项目，其位置与我之前删除的位置相同时，应用程序崩溃（假设我删除了第一个条目，之后每当我点击列表视图中的第一个项目时显示应用程序崩溃）

我遇到应用程序崩溃时出错：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aakashmaroti.fillup/com.example.aakashmaroti.fillup.DisplayDetails}: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0

我的主要活动

package com.example.aakashmaroti.fillup;

import android.app.Dialog;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.database.Cursor;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;


public class StartScreen extends ActionBarActivity implements View.OnClickListener {


    FavoriteList favList = new FavoriteList();

    TextView rid,ts,sd;
    ListView lv;
    Context context=this;
    Find db=new Find(this);
    List<FavoriteList> favoriteList;
    LinearLayout layout;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_start_screen);
        Button b = (Button) findViewById(R.id.AddButton);
        b.setOnClickListener(this);
        lv = (ListView) findViewById(R.id.listview);
        try
        {
            populateListViewFromDatabase();
        } catch (Exception e)
        {
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
            e.printStackTrace();
        }

        lv.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id)
            {
                showsDialog(position);
            }
        });


    }


    @Override
    public void onResume()
    {
        super.onResume();
        try
        {
            populateListViewFromDatabase();
        } catch (Exception e)
        {
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
            e.printStackTrace();
        }

    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onClick(View v) {

        switch (v.getId())
        {
            case R.id.AddButton:
                startActivity(new Intent(this,Form.class));
                break;

            default: break;
        }
    }

    public void populateListViewFromDatabase()throws Exception
    {
        Find info=new Find(this);
        try
        {
            info.open();
            SimpleCursorAdapter myCursorAdapter;
            myCursorAdapter = info.listUp();
            lv.setAdapter(myCursorAdapter);
            info.close();

        } catch (SQLException e)
        {
            e.printStackTrace();
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
        }
    }
    public void showsDialog(int pos)
    {

        pos++;
        String s = "";
        s += pos;
        Intent i = new Intent(getApplicationContext(), DisplayDetails.class);
        i.putExtra("position", s);
        startActivity(i);

        try
        {
            populateListViewFromDatabase();
        } catch (Exception e)
        {
            e.printStackTrace();
        }
    }

}

sqlite数据库管理类

package com.example.aakashmaroti.fillup;

import android.app.Dialog;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by Aakash Maroti on 28-Dec-14.
 */
public class Find
{
    public static final String KEY_ROWID = "_id";
    public static final String KEY_TIMESTAMP= "time_stamp";
    public static final String KEY_IS_SYNCED = "sync";
    public static final String KEY_NameOfCompany="name_of_company";



    private static final String DATABASE_NAME = "FillUpFormsDB";
    private static final String DATABASE_TABLE = "FillUpFormsTable";
    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);
        }



        @Override
        public void onCreate(SQLiteDatabase db)
        {
            db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
                    KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                            KEY_IS_SYNCED +" TEXT NOT NULL, " +
                            KEY_TIMESTAMP +" TEXT NOT NULL, " +
                            KEY_NameOfCompany+" TEXT NOT NULL);"
            );
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
        {
            db.execSQL("DROP TABLE IF EXISTS "+DATABASE_TABLE);
            onCreate(db);
        }     

    }  


    public Find(Context c)
    {
        ourContext = c;
    }

    public Find open()throws SQLException
    {
        ourHelper = new DbHelper(ourContext);
        ourDatabase=ourHelper.getWritableDatabase();
        return this;
    }

    public void close()
    {
        ourHelper.close();
    }


    public long createEntry(String isSynced, String timeStamp, String nameOfCompany)
    {
        ContentValues cv=new ContentValues();
        cv.put(KEY_IS_SYNCED,isSynced);
        cv.put(KEY_TIMESTAMP,timeStamp);
        cv.put(KEY_NameOfCompany,nameOfCompany);        

        return ourDatabase.insert(DATABASE_TABLE,null,cv);

    }

    public SimpleCursorAdapter listUp()
    {

        String columns[]=new String[]{KEY_ROWID,KEY_TIMESTAMP,KEY_IS_SYNCED};
        Cursor c= ourDatabase.query(DATABASE_TABLE,columns,null,null,null,null,null);
        int toViewIDs[] = new int[]{R.id.rowno,R.id.timestamp,R.id.syncdetails};
        SimpleCursorAdapter CursorAdapter;
        CursorAdapter = new SimpleCursorAdapter(ourContext,R.layout.design_row,c,columns,toViewIDs,0);
        return CursorAdapter;
    }

    public String getDetails(long row)
    {
        String columns[]=new String[] {KEY_ROWID, KEY_IS_SYNCED, KEY_TIMESTAMP,KEY_NameOfCompany};
        String result="";        
        Cursor c= ourDatabase.query(DATABASE_TABLE,columns,KEY_ROWID+"="+row,null,null,null,null);
        if(c!=null)
        {
            String r;
            c.moveToFirst();
            r="\nRecord No. : "+c.getString(0)+"\n\nSync Status:"+c.getString(1)+"\n\nTime of Creation:\n"+c.getString(2)+"\n\nName of Company:\n"+c.getString(3);
            return r;
        }

        return result;
    }

    public void DeleteRow(int pos)
    {
        ourDatabase.delete(DATABASE_TABLE,KEY_ROWID+"="+pos,null);
    }
}

显示结果的新活动的类。

package com.example.aakashmaroti.fillup;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;

import java.sql.SQLException;


public class DisplayDetails extends ActionBarActivity implements View.OnClickListener

{

    ImageButton ibSync;
    ImageButton ibDelete;
    TextView DispDetails;
    int pos;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        Bundle extras = getIntent().getExtras();

        String value="1";
        if (extras != null) {
           value = extras.getString("position");
        }
        pos=Integer.parseInt(value);
        setContentView(R.layout.activity_display_details);
        ibSync=(ImageButton)findViewById(R.id.imageButtonSync);
        ibDelete=(ImageButton)findViewById(R.id.imageButtonDelete);
        DispDetails = (TextView)findViewById(R.id.textViewDisplayDetails);
        String s="";

        ibSync.setOnClickListener(this);
        ibDelete.setOnClickListener(this);

        Find info1=new Find(this);
        try
        {
            info1.open();
            s=info1.getDetails(pos);
            info1.close();

        } catch (SQLException e)
        {
            e.printStackTrace();
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
        }
        DispDetails.setText(s);

    }


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

    @Override
    public boolean onOptionsItemSelected(MenuItem item)
    {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings)
        {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onClick(View v)
    {
        if(v.getId()==R.id.imageButtonSync)
        {
            Toast.makeText(getApplicationContext(), "This functionality has not yet been added", Toast.LENGTH_LONG).show();
        }
        if(v.getId()==R.id.imageButtonDelete)
        {   Find info1=new Find(this);
            try
            {
                info1.open();
                info1.DeleteRow(pos);
                info1.close();

            } catch (SQLException e)
            {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
            }


            Toast.makeText(getApplicationContext(), "This record has been successfully deleted", Toast.LENGTH_LONG).show();
            cancel();
        }
    }

    public void cancel()
    {
        this.finish();
        return;
    }
}

listview

中单行的Xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent">


    <TextView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text=""
        android:textStyle="bold"
        android:clickable="true"
        android:id="@+id/rowno"/>   

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text=""
        android:clickable="true"
        android:id="@+id/timestamp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:textStyle="bold"
        android:text=""
        android:clickable="true"
        android:id="@+id/syncdetails"/>

</LinearLayout>

非常感谢任何帮助。

提前致谢。

Answer 1

因为您传递列表视图项位置，它应该是数据库行id。

更改

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
    showsDialog(position);
}

到

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
    TextView pos = (TextView) view.findViewById(R.id.rowno);
    showsDialog(pos.getText().toString());
}

你也说过

Once I delete any entry the row id on the listview doesn't seem to update the row number. (if i delete the first row, the row on top shows 2(should be 1, as it is the new first row)).

但它不会因为这是数据库行id而不是列表视图位置。

Answer 2

您只能在onResume或onCreate中获取Cursor。因此，尽管数据发生了变化，您的Cursor仍保查看LoaderManager类。

sqlite行id不匹配listview - ANDROID

2 个答案: