Array elements have null fields

Question

I've this class:

public class MenuUpElement {

    Class<?> classe;
    String label;
    int viewId;

    public MenuUpElement(int viewId, String label, Class<?> classe) {
        viewId = this.viewId;
        classe = this.classe;
        label = this.label;
    }
}

Then I have a static class StaticClass with this declaration:

public static final MenuUpElement[] menuUpElements = new MenuUpElement[]{
    new MenuUpElement(12, "Main", MainActivity.class)
    , new MenuUpElement(13, "Second", SecondActivity.class)
    };

If I loop through StaticClass.menuUpElements in another class, I found two elements (correct) but all null (wrong):

menuUpElements[0].classe = null
menuUpElements[0].viewId= 0
menuUpElements[0].label= null

menuUpElements[1].classe = null
menuUpElements[1].viewId= 0
menuUpElements[1].label= null

Why?

jedwards · Accepted Answer · 2013-07-30 16:35:36Z

6

The assignments in your constructor are backwards

public MenuUpElement(int viewId, String label, Class<?> classe) {
    viewId = this.viewId;
    classe = this.classe;
    label = this.label;
}

Consider

public MenuUpElement(int viewId, String label, Class<?> classe) {
    this.viewId = viewId;
    this.classe = classe;
    this.label  = label;
}

answered Jul 30, 2013 at 16:35

jedwards

30.3k3 gold badges69 silver badges94 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Geltrude Over a year ago

AH AH AH OH MY GOD DUMB DUMB DUMB!!! I did it tons of times :P Maybe, yesterday I was too tired ;)

Luiggi Mendoza · Accepted Answer · 2013-07-30 16:35:58Z

1

The constructor of MenuUpElement is wrong, you're setting the parameters with the values of the fields. It should be the other way around:

public MenuUpElement(int viewId, String label, Class<?> classe) {
    this.viewId = viewId;
    this.classe = classe;
    this.label = label;
}

answered Jul 30, 2013 at 16:35

Luiggi Mendoza

85.9k16 gold badges159 silver badges354 bronze badges

Collectives™ on Stack Overflow

Array elements have null fields

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related