a.java 文件源码

/**
 * Obtain an {@link Intent} that will launch an explicit target activity specified by
 * this activity's logical parent. The logical parent is named in the application's manifest
 * by the {@link android.R.attr#parentActivityName parentActivityName} attribute.
 * Activity subclasses may override this method to modify the Intent returned by
 * super.getParentActivityIntent() or to implement a different mechanism of retrieving
 * the parent intent entirely.
 *
 * @return a new Intent targeting the defined parent of this activity or null if
 *         there is no valid parent.
 */
@Nullable
public Intent getParentActivityIntent() {
    final String parentName = mActivityInfo.parentActivityName;
    if (TextUtils.isEmpty(parentName)) {
        return null;
    }

    // If the parent itself has no parent, generate a main activity intent.
    final ComponentName target = new ComponentName(this, parentName);
    try {
        final ActivityInfo parentInfo = getPackageManager().getActivityInfo(target, 0);
        final String parentActivity = parentInfo.parentActivityName;
        final Intent parentIntent = parentActivity == null
                ? Intent.makeMainActivity(target)
                : new Intent().setComponent(target);
        return parentIntent;
    } catch (NameNotFoundException e) {
        Log.e(TAG, "getParentActivityIntent: bad parentActivityName '" + parentName +
                "' in manifest");
        return null;
    }
}