findViewById在三星平板电脑上返回null

Question

seems to be a frequent problem with many solutions proposed but I don't succeed in solving it.

all calls to findViewById are successful except the one where expandableListview is created. And it seems to be device dependent. It works in Android Studio, also on a Moto E 4G (5.0.2) but not on a Samsung Galaxy Tab 8.0 (5.1.1).

The full project can be found on github : https://github.com/JohanDegraeve/helpdiabetes-android The module that has the problem is https://github.com/JohanDegraeve/helpdiabetes-android/blob/master/app/src/main/java/com/hippoandfriends/helpdiabetes/Show/Food/ShowSelectedFood.java If anyone could clone the project and try to fix this, it would be very helpful.

Here the onCreate method, creating expandablelistview returns null.

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

    View contentView = LayoutInflater.from(getParent()).inflate(
            R.layout.show_selected_food, null);
    setContentView(contentView);

    // track we come here
    ActivityGroupMeal.group.parent
            .trackPageView(TrackingValues.pageShowSelectedFood);

    expandOrNotDBAdapater = new DbAdapter(this);
    expandOrNotDBAdapater.open();

    functions = new Functions();

    mCalendar = Calendar.getInstance();

    btDelete = (Button) findViewById(R.id.buttonDelete);
    btSaveTemplate = (Button) findViewById(R.id.buttonSaveAsTemplate);
    btLoadTemplate = (Button) findViewById(R.id.buttonLoadTemplate);
    btAddSelectedFoodToTracking = (Button) findViewById(R.id.buttonAddSelectedFoodToTracking);

    btBack = (Button) findViewById(R.id.buttonBack);
    btBack.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            ActivityGroupMeal.group.back();
        }
    });

    expandableListview = (ExpandableListView) findViewById(R.id.expandableListview);

    saveFoodAmount = false;

    fInsulineRatio = 0f;
    fCorrectionFactor = 0f;
    fCalculatedInsulineAmount = 0f;

    dbHelper = new DbAdapter(this);

    DisplayMetrics metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);

    adapter = new CustomExpandableListAdapter(this,
            ActivityGroupMeal.group.getFoodData().dbFontSize,
            metrics.densityDpi);

    listOfSelectedFood = new ArrayList<DBSelectedFood>();
    registerForContextMenu(getListView());

    btAddSelectedFoodToTracking.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            onClickAddSelectedFoodToTracking();
        }
    });

    btDelete.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            // track we come here
            ActivityGroupMeal.group.parent.trackEvent(
                    TrackingValues.eventCategoryMeal,
                    TrackingValues.eventCategoryMealDeleteSelectedFood);

            onClickDeleteAll(v);
        }
    });

    btSaveTemplate.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            // track we come here
            ActivityGroupMeal.group.parent.trackEvent(
                    TrackingValues.eventCategoryMeal,
                    TrackingValues.eventCategoryMealSaveTemplate);

            onClickSaveAsTemplate(v);
        }
    });

    btLoadTemplate.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            // track we come here
            ActivityGroupMeal.group.parent.trackEvent(
                    TrackingValues.eventCategoryMeal,
                    TrackingValues.eventCategoryMealLoadTemplate);

            onClickLoadTemplate(v);
        }
    });

    expandableListview
            .setOnGroupExpandListener(new OnGroupExpandListener() {
                public void onGroupExpand(int groupPosition) {
                    setExpand(1);
                }
            });

    expandableListview
            .setOnGroupCollapseListener(new OnGroupCollapseListener() {
                public void onGroupCollapse(int groupPosition) {
                    setExpand(0);
                }
            });
}

Answer 1

solved

actually on a tablet another layout was used where an id was missing