java.lang.ClassCastException: com.codename1.ui.Label cannot be cast to com.codename1.components.MultiButton

Question

i have been doing the SearchToolBar CodeNameOne API and ran into CLassCastException

for(Component cmp : f.getContentPane()) {
        MultiButton mb = (MultiButton)cmp;
        String line1 = mb.getTextLine1();
        String line2 = mb.getTextLine2();
        boolean show = line1 != null && line1.toLowerCase().indexOf(text) > -1 ||
                line2 != null && line2.toLowerCase().indexOf(text) > -1;
        mb.setHidden(!show);
        mb.setVisible(show);
    }

the output pointed the error on this line:

MultiButton mb = (MultiButton)cmp;

Answer 1

I believe the error is actually in the preceding code and not in the code you have submitted here. The code you have provided here (pulled from the link you also provided) assumes that f.getContentPane() only contains MultiButton and no other type of Component .

In the example you have linked, the creator is iterating through components, casting each one to a MultiButton . In order for this cast to succeed, the object that is assigned to cmp in each iteration of the loop has to actually be a MultiButton .

In your code, while iterating in your for-loop, at one point cmp is assigned a value of type com.codename1.ui.Label , this type is not a MultiButton so the cast fails and throws the runtime exception java.lang.ClassCastException .

To fix: either ensure that the ContentPane only contains MultiButton s or add a check inside your for loop to skip an iteration if the component isn't a MultiButton like follows:

for(Component cmp : f.getContentPane()) {
    if(cmp instanceof MultiButton) {
        // your original for-loop body here
    }
}