如何知道片段何时在 viewpager 中实际可见 [英] How to know when fragment actually visible in viewpager

问题描述

我在 ViewPager 中使用了 4 个片段，因为 ViewPager 会提前加载上一个和下一个片段，并且在片段之间导航时不会调用生命周期方法.那么有什么方法可以检测 Fragment 何时真正可见.提前致谢.

I am using 4 fragments inside a ViewPager ,as ViewPager load the previous and next fragment in advance ,and no lifecycle method is called when navigating between fragments. So is there any way to detect when Fragment is actually visible. Thanks in Advance.

推荐答案

当然.假设 viewPager 是您的 ViewPager 实例，请使用:viewPager.getCurrentItem().

Of course. Assuming that viewPager is your instance of the ViewPager, use: viewPager.getCurrentItem().

在您的 Fragment 中，您可以检查其实例是否对用户可见，如下所示:

Within your Fragment you can check if its instance is visible to the user like so:

@Override
public void setUserVisibleHint(boolean visible) {
    super.setUserVisibleHint(visible);
    if (visible) {
        Log.i("Tag", "Reload fragment");
    }
}

在提出问题之前，请务必彻底搜索答案.例如，您应该首先检查的地方是:https:///developer.android.com/reference/android/support/v4/view/ViewPager.html

Always make sure that you search for answers throughly before asking your question. For instance, the first place you should check would be: https://developer.android.com/reference/android/support/v4/view/ViewPager.html

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