Why is ID not found?

Question

I'm quite a newbie for the eclipse, and I've just started to write some code (actually it's just copy and paste from the website). Can anyone help me about this?

The error is appeared on the R.id.toggleButton1, I had added the line

android:id="@+id/toggleButton1"

in my layout activity_main.xml, but the error is still there :(

The error was:

toggleButton1 cannot be resolved or is not a field

The java source:

package com.example.ledgo;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Toast;
import android.widget.ToggleButton;

public class MainActivity extends Activity {


    ToggleButton tgbutton;
    private Activity activity;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        activity = this;

        tgbutton = (ToggleButton) findViewById(R.id.toggleButton1);
        tgbutton.setOnClickListener(new OnClickListener() {
        ...

The code for my layout xml or called activity_main:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <ToggleButton
        android:id="@+id/toggleButton1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >
        ...

try this add `import com.example.ledgo.R;` at the top of your activity — M D, Apr 18 '14 at 13:12
try " ctrl + shift + o " in Eclipse to organize imports, clean buil your app, that should work — Pararth, Apr 18 '14 at 13:13
no need to import R if the Activity is in the base package (if `com.example.ledgo` is application base package) — Marek Sebera, Apr 18 '14 at 13:14
@user3548900 That's another question, and the answer is probably in the docs. — Joffrey, Apr 18 '14 at 13:27

Joffrey · Accepted Answer · 2014-04-18T13:18:24.177

Problem: Eclipse is telling you that toggleButton1 is not recognized as a field of R.id. This is probably because R.java was not generated properly.

Solution: To force eclipse to re-generate R.java, clean and rebuild your project. This can be done in Eclipse via Project > Clean...

Note: If R is not even recognized, it is probably because your activity is not in the main package, and you need to import R.java. This shouldn't be your case because you've got the error on the field level, not the R.

However, if ever it was the case, I would assume your base package is com.example. If so, you should add the following line below the other imports, just before your activity class declaration:

import com.example.R;

score 1 · Answer 2 · answered Apr 18 '14 at 13:17

1

No need to import R.java.

In eclipse go to Project->Clean and run your application again.

answered Apr 18 '14 at 13:17

Zohra Khan

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score 1 · Answer 3 · edited Jun 20 '20 at 09:12

try
ctrl + shift + o

in Eclipse to organize imports, clean buil your app, that should work

Regarding the onClickListener(), it lets us tell the O.S what to do when that button is clicked.

onClick()

From View.OnClickListener. This is called when the user either touches the item (when in touch mode), or focuses upon the item with the navigation-keys or trackball and presses the suitable "enter" key or presses down on the trackball.

Why is ID not found?

3 Answers3