OnClick doesn't get real button id

Question

I initialised a button with

Button button1 = null;

in the beginning of my activity. After the layout is set, I do

final   Button button1 = (Button) findViewById(R.id.button1);
        button1.setOnClickListener(this);

The onClick looks like that

public void onClick(View v) {
        if(v == button1) {System.out.println("asd");};
        System.out.println(v);
    }

The print shows "I/System.out(22758): android.widget.Button@**405632f0**" and of course, the println("asd") doesn't show up.

I don't want to get the Button@** code for every single button because working with the id of course is much easier.

Someone has in Idea what I did wrong?

Try if v.equals(button1) instead of ==. – Charlie Collins Apr 17 '13 at 14:44 — Charlie Collins, Apr 17 '13 at 14:44

stinepike · Accepted Answer · 2013-04-17T15:08:08.090

2

instead of this

public void onClick(View v) {
        if(v == button1) {System.out.println("asd");};
        System.out.println(v);
    }

use this

public void onClick(View v) {
        if(v.getId() == R.id.button1) {System.out.println("asd");};
        System.out.println(v);
    }

WHY??

because when you are comparing using '==' the it is comparing two objects wheter it is the same reference. that i checks whether both object refers to the same memory.

To solve this you can check their id which is easily comparable.

edited Apr 17 '13 at 15:08

answered Apr 17 '13 at 14:44

stinepike

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Thank you guys, all of the solution worked. I will mark all as answer. Silly me. And thanks for the advice that v.getId() is better, will use that in future. Have a nice day – user2161301 Apr 17 '13 at 14:50
check updated answer for details.. please acceept if any of our answer is helpful – stinepike Apr 17 '13 at 15:01
sorry there was a time limit and I was afk for a few hours – user2161301 Apr 18 '13 at 01:45

score 1 · Answer 2 · edited May 23 '17 at 12:28

1

R.id.button1 is actually an Integer in R.java, it's not a String or anything else that can be truncated to button1. Instead use:

if(v.getId() == R.id.button1)

Also in Java you cannot use == to test equality on non-primitive objects, you must use equals(). Read about the difference in How do I compare strings in Java?

edited May 23 '17 at 12:28

Community

1
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answered Apr 17 '13 at 14:45

Sam

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Thank you guys, all of the solution worked. I will mark all as answer. Silly me. And thanks for the advice that v.getId() is better, will use that in future. Have a nice day – user2161301 Apr 17 '13 at 14:52

score 1 · Answer 3 · answered Apr 17 '13 at 14:46

1

button1 is null. So you compare null and not null. change this:

final   Button button1 = (Button) findViewById(R.id.button1);

to:

button1 = (Button) findViewById(R.id.button1);

and it will work. But you better compare R.id.button1 and v.getId() numbers. Not views itself.

answered Apr 17 '13 at 14:46

Leonidos

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Thank you guys, all of the solution worked. I will mark all as answer. Silly me. And thanks for the advice that v.getId() is better, will use that in future. Have a nice day – user2161301 Apr 17 '13 at 14:51

score 1 · Answer 4 · answered Apr 19 '13 at 14:37

as @Leonidos said, change:

final   Button button1 = (Button) findViewById(R.id.button1);

to:

button1 = (Button) findViewById(R.id.button1);

and, yes, you can compare references: if you see android sources there are two strategies: some people compare reverences like:

if (v == mSomeButton) {

and some use id like:

if (v.getId() == R.id.some_button) {

OnClick doesn't get real button id

4 Answers4