错误：未指定资源类型（在“id”处，值为“@android:id=list”）

Question

错误是什么意思？

package conde.app;

import android.app.Activity;
import android.os.Bundle;
import android.widget.*;
import android.app.*;
import android.view.*;
import android.util.*;
import android.database.sqlite.*;
import android.content.*;
import java.util.*;
import android.database.*;
import android.R.*;

public class MKBApplication extends Activity
{
    /** Called when the activity is first created. */

    Button aBtn = (Button) findViewById(R.id.addBtn);
    Button dBtn = (Button) findViewById(R.id.deleteBtn);
    private GroceryDataSource datasource;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        datasource = new GroceryDataSource(this);
        datasource.open();
        List<Grocery> values = datasource.getAllGroceryItems();
        ArrayAdapter<Grocery> adapter = new ArrayAdapter<Grocery>(this,
            android.R.layout.simple_list_item_2, values);
        setListAdapter(adapter);
    }

    public void onClick(View view) {
        @SuppressWarnings("unchecked")
        ArrayAdapter<Grocery> adapter = (ArrayAdapter<Grocery>) getListAdapter();
        Grocery grocery = null;
        switch(view.getId()){
            case R.id.addBtn:
                String[] name = new String[] { "Pork", "Chicken", "Onion" };
                String[] quantity = new String[] { "1/2 kilo", "3 kilos", "1 kilo" };
                int nextInt = new Random().nextInt(3);
                grocery = datasource.createGroceryItem(name[nextInt], quantity[nextInt]);
                adapter.add(grocery);
            break;
            case R.id.deleteBtn:
                if (getListAdapter().getCount() > 0) {
                    grocery = (Grocery) getListAdapter().getItem(0);
                    datasource.deleteGroceryItem(grocery);
                    adapter.remove(grocery);
                }
            break;
        }
        adapter.notifyDataSetChanged();
    }

    @Override
    protected void onResume() {
        datasource.open();
        super.onResume();
    }

    @Override
    protected void onPause() {
        datasource.close();
        super.onPause();
    }
}

这是我的 xml 文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Hello World, MKBApplication"
    />
<Button
    android:id="@+id/addBtn"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="ADD"
/>
<Button
    android:id="@+id/deleteBtn"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="DELETE"
/>

<ListView
    android:id="@android:id=list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
/>

</LinearLayout>

Answer 1

<ListView
    android:id="@android:id=list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
/>

应该是

<ListView
    android:id="@+id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
/>