如何使用PagerAdapter在ViewPager中调用destroyItem（）

Question

我有一个场景，我需要在应用程序关闭或调用onDestroy()时销毁ViewPager上的项目，但在ViewPager中没有API可以扩展PagerAdapter。 destroyItem()只在刷页时被调用，这取决于在mViewPager.setOffscreenPageLimit(int)中保存多少页。有没有办法强制ViewPager调用destroyItem()？

Answer 1

我假设您的类从PagerAdapter扩展名为MyPagerAdapter。

my pager adapter.Java

public class MyPageAdapter extends FragmentPagerAdapter {
    ...
}

main activity.Java

public class MainActivity extends AppCompatActivity {

    ViewPager viewPager;
    MyPageAdapter pagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        pagerAdapter = new MyPageAdapter(getSupportFragmentManager());

        viewPager = findViewById(R.id.viewpager);
        viewPager.setAdapter(pagerAdapter);
    }

    @Override
    protected void onDestroy() {
        // For example, call destroyItem when activity get destroyed.
        forceDestroyCurrentItemInViewPager();
        super.onDestroy();
    }

    // Call this method to call destroyItem() for current item in view pager.
    private void forceDestroyCurrentItemInViewPager() {
        int position = viewPager.getCurrentItem();
        Object object = pagerAdapter.getItem(position);
        pagerAdapter.destroyItem(viewPager, position, object);
    }
}