Click listener for ALL buttons

Question

I have multiple buttons in my app and I would like to have a single click listener for all buttons in R.layout.fragment_general . This is what I have tried:

View view = inflater.inflate(R.layout.fragment_general, container, false);
@SuppressLint("ResourceType") ViewGroup group = (ViewGroup) view.findViewById(R.layout.fragment_general);
View v;
for(int i = 0; i < group.getChildCount(); i++) {
    v = group.getChildAt(i);
    if(v instanceof Button) {
        v.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                System.out.println("A button has been clicked");
            }
        });
    }
}

My app will crash and I get the error:

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.ViewGroup.getChildCount()' on a null object reference

How should it be done correctly?

Answer 1

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.ViewGroup.getChildCount()' on a null object reference

It means, that your group is null. That happened brcause of this

@SuppressLint("ResourceType") ViewGroup group = (ViewGroup) view.findViewById(R.layout.fragment_general);

You should write yours ViewGroups id in findViewbyId(), but not the fragments layout name.