CODEWITHSUNDEEP
javaarraysnull
Geltrude
Geltrude

Reputation: 1095

Array elements have null fields

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?

Upvotes: 0

Views: 58

Answers (2)

Luiggi Mendoza
Luiggi Mendoza

Reputation: 85779

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;
}

Upvotes: 1

jedwards
jedwards

Reputation: 30210

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;
}

Upvotes: 6

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