I am using the viewfager and fragment on Android, and I would like to find the width of the linear layout in the fragment.

I'm using a viewfager and a fragment on Android. Among them, I want to find the width of the linear layout in one fragment. I'm a student practicing examples.

private View rootView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            rootView = (ViewGroup)inflater.inflate(R.layout.tab_fragment_1, container, false);

        return rootView;
    }

public void onActivityCreated(Bundle savedInstanceState) {
     super.onActivityCreated(savedInstanceState);

    rootView.getViewTreeObserver().addOnGlobalLayoutListener(mGlobalLayoutListener);

    LinearLayout    linearForTime = (LinearLayout) rootView.findViewById(R.id.time);    

    int Width = forTimeWidth.getMeasuredWidth() / 5;
}

The code is as above. I want to find the width of the linear layout in tab_fragment1, but if I write the code as above, it will not be executed with the following error.

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.widget.LinearLayout.getMeasuredWidth()' on a null object reference at example.com.mptermui.TabFragment1.onActivityCreated(TabFragment1.java:149)

Code 149 is int Width = for Time Width.getMeasuredWidth() / 5; here.

fragment android

2022-09-22 21:32

1 Answers

The following code to find the width of the code you wrote,

LinearLayout linearForTime = (LinearLayout) rootView.findViewById(R.id.time);
int Width = forTimeWidth.getMeasuredWidth() / 5;

Please write inside ViewTreeObserver.OnGlobalLayoutListener as shown below.

rootView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
        rootView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
        LinearLayout linearForTime = (LinearLayout) rootView.findViewById(R.id.time);
        int Width = linearForTime.getMeasuredWidth() / 5;
    }
});

If the same error occurs even after writing it like this, it will be necessary to verify that R.id.time exists inside the layout file tab_fragment_1.xml.

2022-09-22 21:32

If you have any answers or tips

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