Android SimpleCursorAdapter Logcat錯誤消息

Question

單擊我的應用程序中的按鈕后，logcat的結果

02-03 12:40:44.015: E/AndroidRuntime(1259): FATAL EXCEPTION: main
02-03 12:40:44.015: E/AndroidRuntime(1259): java.lang.IllegalStateException: Could not execute method of the activity
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.view.View$1.onClick(View.java:3633)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.view.View.performClick(View.java:4240)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.view.View$PerformClick.run(View.java:17721)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.os.Handler.handleCallback(Handler.java:730)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.os.Handler.dispatchMessage(Handler.java:92)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.os.Looper.loop(Looper.java:137)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.app.ActivityThread.main(ActivityThread.java:5103)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at java.lang.reflect.Method.invokeNative(Native Method)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at java.lang.reflect.Method.invoke(Method.java:525)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at dalvik.system.NativeStart.main(Native Method)
02-03 12:40:44.015: E/AndroidRuntime(1259): Caused by: java.lang.reflect.InvocationTargetException
02-03 12:40:44.015: E/AndroidRuntime(1259):     at java.lang.reflect.Method.invokeNative(Native Method)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at java.lang.reflect.Method.invoke(Method.java:525)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.view.View$1.onClick(View.java:3628)
02-03 12:40:44.015: E/AndroidRuntime(1259):     ... 11 more
02-03 12:40:44.015: E/AndroidRuntime(1259): Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:303)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.support.v4.widget.CursorAdapter.init(CursorAdapter.java:174)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.support.v4.widget.CursorAdapter.<init>(CursorAdapter.java:122)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.support.v4.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:54)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at android.support.v4.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:63)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at com.example.universitybudgetub.MainMenu.populateListViewFromDB(MainMenu.java:174)
02-03 12:40:44.015: E/AndroidRuntime(1259):     at com.example.universitybudgetub.MainMenu.addRecord(MainMenu.java:135)
02-03 12:40:44.015: E/AndroidRuntime(1259):     ... 14 more

我想要實現的是使用“ getAllRows”方法顯示來自數據庫的信息，以下代碼段將顯示我的Java類。

DBAdapter.java-getAllRows方法

public Cursor getAllRows() {
    String where = null;
    Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS, 
                        where, null, null, null, null, null);
    if (c != null) {
        c.moveToFirst();
    }
    return c;
}

MainMenu.java

package com.example.universitybudgetub;

import java.io.File;

import android.database.Cursor;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;


public class MainMenu extends FragmentActivity{

    DBAdapter db = new DBAdapter(this); //Initiate DB class methods
    SectionsPagerAdapter mSectionsPagerAdapter;
    ViewPager mViewPager;


    //OnCreate
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_menu);
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);
    }

    public void onClick(View v){
            String destPath = "/data/data/" + getPackageName() + "/databases/ExpensesDB";
            @SuppressWarnings("unused")
            File f = new File(destPath);
    }

    //OnCreateOptionsMenu 
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return true;
    }

    //SectionsPagerAdapter Controls which Fragment is retrieved for each page
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            Fragment fragment;
            switch (position) {
                case 0:
                    fragment = new Fragment1();
                    break;
                case 1:
                    fragment = new Fragment2();
                    break;
                case 2:
                    fragment = new Fragment3();
                    break;
                case 3:
                    fragment = new Fragment4();
                    break;
                case 4:
                    fragment = new Fragment5();
                    break;
                default:
                    fragment  = null;
                    break;
            }
            return fragment;
        }

        //Returns the amount of pages to display
        @Override
        public int getCount() {
            // Show 3 total pages.
            return 5;
        }

        //Page Title
        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
            case 0:
                return getString(R.string.title_section1);
            case 1:
                return getString(R.string.title_section2);
            case 2:
                return getString(R.string.title_section3);
            case 3:
                return getString(R.string.title_section4);
            case 4:
                return getString(R.string.title_section5);
            }
            return null;
        }
    }

    //Add New Record
    public void addRecord (View v){

        //Get data from form
        EditText foodTxt = (EditText)findViewById(R.id.editText_food);
        EditText taxiTxt = (EditText)findViewById(R.id.editText_taxi);
        EditText clothesTxt = (EditText)findViewById(R.id.editText_clothes);
        EditText sportsTxt = (EditText)findViewById(R.id.editText_sports);
        EditText supermarketTxt = (EditText)findViewById(R.id.editText_supermarket);
        EditText clubs_barsTxt = (EditText)findViewById(R.id.editText_clubs);
        EditText owed_moneyTxt = (EditText)findViewById(R.id.editText_owed_money);
        EditText otherTxt = (EditText)findViewById(R.id.editText_other);
        EditText electric_gasTxt = (EditText)findViewById(R.id.editText_electric_gas);
        EditText waterbillTxt = (EditText)findViewById(R.id.editText_water);
        EditText houseTxt = (EditText)findViewById(R.id.editText_house);
        EditText rentTxt = (EditText)findViewById(R.id.editText_rent);
        EditText internetTxt = (EditText)findViewById(R.id.editText_internet);

        db.open();
        @SuppressWarnings("unused")
        long id = db.insertRecord(foodTxt.getText().toString(), clothesTxt.getText().toString(), 
                supermarketTxt.getText().toString(), taxiTxt.getText().toString(), sportsTxt.getText().toString(), 
                clubs_barsTxt.getText().toString(), owed_moneyTxt.getText().toString(), otherTxt.getText().toString(), 
                electric_gasTxt.getText().toString(), waterbillTxt.getText().toString(), rentTxt.getText().toString(),
                houseTxt.getText().toString(), internetTxt.getText().toString()); 

        populateListViewFromDB(); //Re-populate the list after new record is added

        db.close();

        //Set editText fields to empty
        foodTxt.setText("");
        taxiTxt.setText("");
        clothesTxt.setText("");
        sportsTxt.setText("");
        supermarketTxt.setText("");
        clubs_barsTxt.setText("");
        owed_moneyTxt.setText("");
        otherTxt.setText("");
        electric_gasTxt.setText("");
        waterbillTxt.setText("");
        houseTxt.setText("");
        rentTxt.setText("");
        internetTxt.setText("");
        Toast.makeText(MainMenu.this, "Expenses Added", Toast.LENGTH_LONG).show();
    }

    private void populateListViewFromDB() {
        Cursor cursor = db.getAllRows();

        //Allow activity to manage lifetime of the cursor
        //DEPRECATED!
        startManagingCursor(cursor);

        //Setup mapping from cursor to view fields
        String[] fromFieldNames = new String[] 
                {DBAdapter.KEY_FOOD, DBAdapter.KEY_CLOTHES, DBAdapter.KEY_SUPERMARKET, DBAdapter.KEY_TAXI, DBAdapter.KEY_SPORTS,
                    DBAdapter.KEY_CLUBS_BARS, DBAdapter.KEY_OWED_MONEY, DBAdapter.KEY_OTHER, DBAdapter.KEY_ELECTRIC_GAS, DBAdapter.KEY_WATERBILL,
                        DBAdapter.KEY_RENT, DBAdapter.KEY_HOUSE, DBAdapter.KEY_INTERNETBILL,};
        int[] toViewIDs = new int[]
                {R.id.textView_itemfood, R.id.textView_itemclothes, R.id.textView_itemsupermarket, R.id.textView_itemtaxi, R.id.textView_itemsports,
                    R.id.textView_itemclubs, R.id.textView_itemowed, R.id.textView_itemother, R.id.textView_itemelectric, R.id.textView_itemwater, 
                        R.id.textView_itemrent, R.id.textView_itemhouse, R.id.textView_iteminternet,};

        //Create Adapter to map columns of the DB into elements in the UI
        SimpleCursorAdapter myCursorAdapter = new SimpleCursorAdapter(
                this, //Context
                R.layout.history_expenses_layout, //Row layout template
                cursor, //cursor (set of DB REcords to map)
                fromFieldNames, //DB Column names
                toViewIDs // View IDs to put information in
                );

        //Set the adapter for the list view
        ListView myList = (ListView) findViewById(R.id.listViewFromDB);
        myList.setAdapter(myCursorAdapter);
    }


}

MainMenu.java中要注意的部分是它在片段菜單上運行。 方法addRecord只是將用戶輸入添加到數據庫中，完成此操作后，它將運行方法“ populateListViewFromDB”以在不同的活動中填充listView，從而將信息從數據庫顯示到listView。

任何幫助，將不勝感激！

編輯

我在代碼中添加了“ _id”-但現在它在logcat中說了另一個錯誤：

02-03 16:19:48.172: D/AndroidRuntime(959): Shutting down VM
02-03 16:19:48.182: W/dalvikvm(959): threadid=1: thread exiting with uncaught exception (group=0x41465700)
02-03 16:19:48.322: E/AndroidRuntime(959): FATAL EXCEPTION: main
02-03 16:19:48.322: E/AndroidRuntime(959): java.lang.IllegalStateException: Could not execute method of the activity
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.view.View$1.onClick(View.java:3633)
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.view.View.performClick(View.java:4240)
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.view.View$PerformClick.run(View.java:17721)
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.os.Handler.handleCallback(Handler.java:730)
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.os.Handler.dispatchMessage(Handler.java:92)
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.os.Looper.loop(Looper.java:137)
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.app.ActivityThread.main(ActivityThread.java:5103)
02-03 16:19:48.322: E/AndroidRuntime(959):  at java.lang.reflect.Method.invokeNative(Native Method)
02-03 16:19:48.322: E/AndroidRuntime(959):  at java.lang.reflect.Method.invoke(Method.java:525)
02-03 16:19:48.322: E/AndroidRuntime(959):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
02-03 16:19:48.322: E/AndroidRuntime(959):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
02-03 16:19:48.322: E/AndroidRuntime(959):  at dalvik.system.NativeStart.main(Native Method)
02-03 16:19:48.322: E/AndroidRuntime(959): Caused by: java.lang.reflect.InvocationTargetException
02-03 16:19:48.322: E/AndroidRuntime(959):  at java.lang.reflect.Method.invokeNative(Native Method)
02-03 16:19:48.322: E/AndroidRuntime(959):  at java.lang.reflect.Method.invoke(Method.java:525)
02-03 16:19:48.322: E/AndroidRuntime(959):  at android.view.View$1.onClick(View.java:3628)
02-03 16:19:48.322: E/AndroidRuntime(959):  ... 11 more
02-03 16:19:48.322: E/AndroidRuntime(959): Caused by: java.lang.NullPointerException
02-03 16:19:48.322: E/AndroidRuntime(959):  at com.example.universitybudgetub.MainMenu.populateListViewFromDB(MainMenu.java:184)
02-03 16:19:48.322: E/AndroidRuntime(959):  at com.example.universitybudgetub.MainMenu.addRecord(MainMenu.java:135)
02-03 16:19:48.322: E/AndroidRuntime(959):  ... 14 more

Answer 1

所有CursorAdapter都需要在光標投影中添加一列_id 。

您不會在問題中公開過多的數據庫代碼，而是在此處查詢：

Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS, 
                    where, null, null, null, null, null);

應該在ALL_KEYS包含一個_id列。

添加_id一種簡單方法是為rowid加上別名（如果存在，則rowid本身就是INTEGER PRIMARY KEY列的別名）：添加

"rowid AS _id"

到ALL_KEYS投影。

Answer 2

問題是由於以下原因：

引起原因：java.lang.IllegalArgumentException：列“ _id”不存在

android.support.v4.widget.SimpleCursorAdapter。（SimpleCursorAdapter.java:63）

02-03 12：40：44.015：E / AndroidRuntime（1259）：位於com.example.universitybudgetub.MainMenu.populateListViewFromDB（MainMenu.java:174）

com.example.universitybudgetub.MainMenu.addRecord（MainMenu.java:135）02-03 12：40：44.015：E / AndroidRuntime（1259）：...還有14個

檢查在字符串數組“ fromFieldNames”中使用的列名。