Chapter 2 To Do List errors

louie2107 · November 30th, 2009, 10:54 PM

I keep getting errors from eclipse that the arraylist cannot be resolved. Any help would be great.

Thanks,
Sam

Code:

package com.paad.todolist;

import android.app.Activity;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.ListView;

public class ToDoList extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle icicle) {
        setContentView(R.layout.main);
        ListView myListView = (ListView)findViewById(R.id.myListView);
        final EditText myEditText = (EditText)findViewById(R.id.myEditText);
        final ArrayList<String> todoItems  = new ArrayList<String>();        aa = new ArrayAdapter<String>(this,
        							  android.R.layout.simple_list_item_1,
        							  todoItems);
        myListView.serAdapter(aa);
        myEditText.setOnKeyListener(new OnKeyListener() {
        	public boolean onKey(View v, int keycode, KeyEvent event) {
        		if (event.getAction() == KeyEvent.ACTION_DOWN)
        			if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER)
        			{
        				todoItems.add(0, myEditText.getText().toString());
        				aa.notifyDataSetChanged();
        				myEditText.setText("");
        				return true;
        			}
        		return false;
        			}
        	}
        }
    }
}

ajh158 · December 1st, 2009, 12:22 AM

You need to import the class. To do this manually, place the following line with the other import statements at the top of the file:
import java.util.ArrayList;

In Eclipse, there is an "Organize Imports" action that is useful for doing this automatically. Look under Source->Organize Imports. By default, the hotkey is Control/Command-Shift-O (windows/mac).

Hope that helps!

louie2107 · December 1st, 2009, 12:53 AM

Thanks for the tip, it helped to get rid of the errors on arraylist. I also get errors for the keylistener, keyevent, array, and array adapter. I've been trying to copy things word for word from the book and I am wondering why the tip you gave me isn't in the book. I'm new to all of this and am grateful for any help you can give me.

ajh158 · December 1st, 2009, 02:07 AM

I noticed those other imports were missing... Try using the "Organize Imports" action I mentioned. That should take care of all of the import errors you are getting.

I use "Organize Imports" all the time to keep autocomplete working as I reference external classes for the first time inside a class definition.

louisx · January 12th, 2010, 05:09 PM

When I try to test the first ToDoList example I keep receiving the above message:

"Error:Attempt to include a core VM class in something other than a
core library. "

The message also includes a paragraph of snide comments from whoever programmed the message -- not appreciated by those of us new to Android.

What does the message mean, and how do I fix this? Eclipse shows no errors in the code, so I'm wondering if there is something in the properties or organization of the project that is causing the problem. Does anyone here know?

djanello · March 23rd, 2011, 08:56 AM

[SOLVED]

When trying to run/debug the program, I get "simple_list_item_1 cannot be resolved or is not a field".

I've imported the necessary packages and I have to agree with the error since my R.java somehow doesn't include a variable like 'simple_list_item_1'. Neither has this been mentioned in the example.

I'm left wondering how the program recognises the android simple_list_item_1 when there's no reference or import to it? (I've just started with android, coming from mobile 6.5 with C# and am trying to get a feel for the differences between the two.)

used imports:

Code:

import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnKeyListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;

my R.java looks like this;

Code:

package mypackage.todolist;

public final class R {
    public static final class attr {
    }
    public static final class drawable {
        public static final int icon=0x7f020000;
    }
    public static final class id {
        public static final int myEditText=0x7f050000;
        public static final int myListView=0x7f050001;
    }
    public static final class layout {
        public static final int main=0x7f030000;
    }
    public static final class string {
        public static final int app_name=0x7f040001;
        public static final int hello=0x7f040000;
    }
}

note: EditText and ListView were added to main.xml. I've also already added the onKeyListener.

Anyone know what I'm missing?

EDIT:
It seems that the reference to R should've been Android.R. I was thinking too much and changed that which made the program go awry. Should be ok now, although I'm still getting a fatal error on startup in the emulator, but atleast this's been solved.

Regards,

Djanello.