安卓分割空字符串数组长度为1

空值分割总有1个长度，困惑了很久。

Java split分割空字符串得到的数组长度为1_java数组length为1的情况-CSDN博客

计数

int count_bookmark = 0;
SharedPreferences SP;

SP = PreferenceManager.getDefaultSharedPreferences(this);
String s = SP.getString("bookmarks", "");        
if (!s.isEmpty()) {
    String[] sa = s.split(":");
    count_bookmark = sa.length;
}

加载

void loadBookmarks() {
    String s = sharedPreferences.getString("bookmarks", "");    
    String[] sa = s.split(":");
    Collections.addAll(list, sa);
    list.remove("");
    adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, list);
    listView.setAdapter(adapter);
}

添加

SharedPreferences SP;
SharedPreferences.Editor SPE;

String s = SP.getString("bookmarks", "");
if (s.isEmpty())
    SPE.putString("bookmarks", path);
else
    SPE.putString("bookmarks", ":" + path);
SPE.apply();