H07000223/FlycoTabLayout · error · IllegalStateException

Titles can not be EMPTY !

Error message

Titles can not be EMPTY !

What it means

In SlidingTabLayout.setViewPager(ViewPager, String[]), a null or zero-length titles array throws IllegalStateException "Titles can not be EMPTY !". Each tab needs a title string; an empty array would leave the tab strip blank and desynchronized from the adapter.

Solutions

1. Pass a titles array with exactly one non-null entry per page.
2. Validate titles != null && titles.length > 0 before the call, and also match vp.getAdapter().getCount() (a later check throws otherwise).
3. Defer setViewPager until titles are loaded, or use the 1-arg setViewPager with an adapter that supplies titles via getPageTitle().
4. Catch IllegalStateException when empty titles can legitimately occur at startup.

Example fix

// before
slidingTabLayout.setViewPager(viewPager, new String[0]);
// after
String[] titles = {"Tab 1", "Tab 2"};
slidingTabLayout.setViewPager(viewPager, titles);

if (titles != null && titles.length > 0 && titles.length == vp.getAdapter().getCount()) {
    slidingTabLayout.setViewPager(vp, titles);
}

boolean isValidTitleSet(ViewPager vp, String[] titles) {
    return titles != null && titles.length > 0
        && vp != null && vp.getAdapter() != null
        && titles.length == vp.getAdapter().getCount();
}

try {
    slidingTabLayout.setViewPager(vp, titles);
} catch (IllegalStateException e) {
    Log.e("SlidingTabLayout", "titles null/empty", e);
}

When it happens

Trigger: Passing titles == null or titles.length == 0 to the two-argument setViewPager; passing an array built from an empty list or missing string resources.

Common situations: Titles loaded asynchronously and not yet populated when setViewPager runs; localized string arrays resolving to nothing; copy-paste of the 1-arg setViewPager call without adding titles.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• TabEntitys can not be NULL or EMPTY !
• Titles can not be NULL or EMPTY !
• Titles length must be the same as the page count !
• ViewPager or ViewPager adapter can not be NULL !
• ViewPager can not be NULL !

AI-assisted analysis of H07000223/FlycoTabLayout@528fcffe88 (2026-09-08). Data as JSON: /api/errors/7ad42adb028e1489. Report an issue: GitHub.

Appendix: source

Thrown at FlycoTabLayout_Lib/src/main/java/com/flyco/tablayout/SlidingTabLayout.java:192

        if (vp == null || vp.getAdapter() == null) {
            throw new IllegalStateException("ViewPager or ViewPager adapter can not be NULL !");
        }

        this.mViewPager = vp;

        this.mViewPager.removeOnPageChangeListener(this);
        this.mViewPager.addOnPageChangeListener(this);
        notifyDataSetChanged();
    }

    /** 关联ViewPager,用于不想在ViewPager适配器中设置titles数据的情况 */
    public void setViewPager(ViewPager vp, String[] titles) {
        if (vp == null || vp.getAdapter() == null) {
            throw new IllegalStateException("ViewPager or ViewPager adapter can not be NULL !");
        }

        if (titles == null || titles.length == 0) {
            throw new IllegalStateException("Titles can not be EMPTY !");
        }

        if (titles.length != vp.getAdapter().getCount()) {
            throw new IllegalStateException("Titles length must be the same as the page count !");
        }

        this.mViewPager = vp;
        mTitles = new ArrayList<>();
        Collections.addAll(mTitles, titles);

        this.mViewPager.removeOnPageChangeListener(this);
        this.mViewPager.addOnPageChangeListener(this);
        notifyDataSetChanged();
    }

    /** 关联ViewPager,用于连适配器都不想自己实例化的情况 */
    public void setViewPager(ViewPager vp, String[] titles, FragmentActivity fa, ArrayList<Fragment> fragments) {
        if (vp == null) {

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