Android : Android java cannot remove empty element

Hello i want to remove all empty element.. i use code below this, but did not working..

sejarahToken.removeAll(Collections.singleton(""));
    sejarahToken.removeAll(Arrays.asList(""));
    for (String st : sejarahToken) {
        writingFile(st);
    }

same as using this code:

 sejarahToken.removeAll(Collections.singleton(null));
 sejarahToken.removeAll(Arrays.asList(null,""));

here's output the sejarahToken arraylist on txt file.. there are still empty values:

Leonardo
da
Vinci
dari
Italia
dan
Otto
Lilienthal
dari
Jerman
telah
mendahuluinya


Tetapi
ternyata
jauh
sebelumnya
semua
sudah
didahului
oleh
seorang