问来源Not Found main.xml开始开发Android4应用程序

EN

package net.learn2develop.Basicviews5;

import android.app.ListActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;


public class BasicViews5Activity extends ListActivity {

    String[] presidents;

/** called when there activity is first created */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    ListView lstView = getListView();
    // lstView.setChoiceMode(ListView.CHOICE_MODE_NONE);
    //lstView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    lstView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
    lstView.setTextFilterEnabled(true);

    presidents = 
            getResources().getStringArray(R.array.presidents_array);

    setListAdapter(new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_checked, presidents));
}

public void onListItemClick(
        ListView parent, View v, int position, long id)
{
    Toast.makeText(this,
            "You have selceted " + presidents[position],
            Toast.LENGTH_SHORT).show();
}

public void onClick(View view) {
    ListView lstView = getListView();

    String itemsSelected = "Selcted items: \n";
    for (int i=0; i<lstView.getCount(); i++) {
        if (lstView.isItemChecked(i)) {
            itemsSelected += lstView.getItemAtPosition(i) + "\n";
        }
    }
    Toast.makeText(this, itemsSelected, Toast.LENGTH_LONG).show();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.basic_views5, menu);
    return true;
}

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".BasicViews5Activity" >

<Button 
    android:id="@+id/btn"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Show selceted items"
    android:onClick="onClick" />

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

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<string name="action_settings">Settings</string>
<string name="hello_world">Hello world!</string>
<string name="app_name">BasicViews5</string>
<string-array name="presidents_array">
    <item>Dwight D. Eisenhower</item>
    <item>John F. Kennedy</item>
    <item>Lyndon B. Johnson</item>
    <item>Richard Nixon</item>
    <item>Gerald Ford</item>
    <item>Jimmy Carter</item>
    <item>Ronald Reagen</item>
    <item>George H. W. Bush</item>
    <item>Bill Clinton</item>
    <item>George W. Bush</item>
    <item>Barack Obama</item>
</string-array>

</resources>

setContentView(R.layout.main);