我已经经历了与此相关的在本网站上的各种问题搜索，但我未能解决这个问题我收到。

我想从数据库ID上点击列表视图项目

这是我的类别类：

 包com.example.reminders;

进口的java.util.List;

进口android.app.ListActivity;
进口android.content.Intent;
进口android.database.Cursor;
进口android.os.Bundle;
进口android.view.View;
进口android.widget.AdapterView;
进口android.widget.AdapterView.OnItemClickListener;
进口android.widget.ArrayAdapter;
进口android.widget.ListView;
进口android.widget.Toast;

公共类分类扩展ListActivity {

    @覆盖
    公共无效的onCreate（包savedInstanceState）{
        super.onCreate（savedInstanceState）;
        DBAdapter DB =新DBAdapter（Categories.this）;
        db.open（）;
        名单＆LT;字符串＆GT; CS = db.getAllCategoriesList（）;
        setListAdapter（新ArrayAdapter＆LT;字符串＆GT;（这一点，R.layout.activity_categories，CS））;
        ListView控件的ListView = getListView（）;
        listView.setTextFilterEnabled（真正的）;
        listView.setOnItemClickListener（新OnItemClickListener（）{
            公共无效onItemClick（适配器视图＆LT;＆GT;母公司视图中查看，
                    INT位置，长的id）{
                //单击时，显示出与TextView的文字敬酒

                 光标CUR =（光标）parent.getItemAtPosition（位置）;
                Toast.makeText（getApplicationContext（），
                ID：+编号+的位置：+位置+ROWID：+ cur.getInt（cur.getColumnIndex（_ ID）），Toast.LENGTH_LONG）.show（）;
            }
        }）;
        db.close（）;


    }


}
 

在DBAdapter类中定义的

getAllCategoriesList功能是：

  // ---检索所有类别数据---
    公开名单＆LT;字符串＆GT; getAllCategoriesList（）
    {
        的String []列=新的String [] {KEY_NAME2};
        光标C = db.query（DATABASE_TABLE2，列，NULL，NULL，NULL，NULL，
            KEY_NAME2）;
       //字符串结果=;
        名单＆LT;字符串＆GT;结果=新的ArrayList＆LT;字符串＆GT;（）;
        INT ICM = c.getColumnIndex（KEY_NAME2）;

        为（c.moveToFirst（）;！c.isAfterLast（）; c.moveToNext（））{
            results.add（c.getString（ICM））;
        }
        返回结果;

    }
 

当我跑的例子code以下错误来了：

  10-01 15：05：22.507：E / AndroidRuntime（20846）：java.lang.ClassCastException：java.lang.String中不能转换为android.database.Cursor
 

解决方案

你是不是从数据库（仅KEY_NAME2列）查询_i​​d，所以你不能从适配器得到它。

这行：

 光标CUR =（光标）parent.getItemAtPosition（位置）;
 

是完全错误的。您正在试图施放一个String（这是由返回 ArrayAdapter＆LT;字符串＆GT; 来一个光标，它不能正常工作

您所要做的，就是用的CursorAdapter （或 SimpleCursorAdapter ）为您的ListView。光标应该查询至少_id和KEY_NAME2。

通过这个适配器的getItem（INT位置）将返回一个指针设置为要求的位置。然后，所有你需要做的就是 cursor.getInt（cursor.getColumnIndex（_ ID））和你的存在。

I have searched through various questions related to this on this website but i am unable to resolve the issue i am getting.

I want to get id from database on click of listview item

This is my categories class:

package com.example.reminders;

import java.util.List;

import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class Categories extends ListActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        DBAdapter db = new DBAdapter(Categories.this);
        db.open();
        List<String> cs = db.getAllCategoriesList();
        setListAdapter(new ArrayAdapter<String>(this, R.layout.activity_categories,cs));
        ListView listView = getListView();
        listView.setTextFilterEnabled(true);
        listView.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // When clicked, show a toast with the TextView text

                 Cursor cur = (Cursor) parent.getItemAtPosition(position);
                Toast.makeText(getApplicationContext(),
                "id:"+id+"position:"+position+"rowid:"+cur.getInt(cur.getColumnIndex("_id")), Toast.LENGTH_LONG).show();
            }
        }); 
        db.close();


    }


}

getAllCategoriesList function defined in the DBAdapter class is :

//---retrieves all the category data---
    public List<String> getAllCategoriesList() 
    {
        String[] columns = new String[] {KEY_NAME2};
        Cursor c = db.query(DATABASE_TABLE2, columns, null, null, null, null,
            KEY_NAME2);     
       // String results = "";
        List<String> results = new ArrayList<String>();
        int iCM = c.getColumnIndex(KEY_NAME2);

        for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
            results.add(c.getString(iCM));
        }
        return results;

    }

When i ran the example code the following error comes:

10-01 15:05:22.507: E/AndroidRuntime(20846): java.lang.ClassCastException: java.lang.String cannot be cast to android.database.Cursor

You are not querying the _id from the database (only the KEY_NAME2 column), so you're not able to get it from the adapter.

This line:

Cursor cur = (Cursor) parent.getItemAtPosition(position);

is entirely wrong. You are trying to cast a String (which is returned by ArrayAdapter<String> to a cursor, which can never work.

What you have to do, is use a CursorAdapter (or SimpleCursorAdapter) for your ListView. The cursor should query at least for _id and KEY_NAME2.

With this adapter the getItem(int position) will return a cursor set to requested position. Then all you need to do is cursor.getInt(cursor.getColumnIndex("_id")) and you're there.