android - isAdded() 是否与 Android Fragment 中的 null != getActivity() 相同？

Question

我想知道这两种方法是否会导致相同的结果，或者一种比另一种更好。

if(isAdded()){
//do something with activity since fragment is currently added to its activity.
}

和

if(null != getActivity()){
//do something with activity. Its not null
}

Answer 1

isAdded() 更适合在几乎所有情况下使用，原因有以下两个:

1. isAdded() 如果 Fragment 当前已添加到其 Activity 。 getActivity() 只返回关联的 Activity 。在大多数情况下，这将返回相同的 bool 值，但为了安全起见最好

2. 编写的代码更少

源代码:

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/5.1.1_r1/android/app/Fragment.java/

/**
 * Return the Activity this fragment is currently associated with.
 */
final public Activity getActivity() {
    return mActivity;
}

/**
 * Return true if the fragment is currently added to its activity.
 */
final public boolean isAdded() {
    return mActivity != null && mAdded;
}