java -- List去重

for (int i = 0; i < newdt.size(); i++) {
    for (int j = newdt.size() - 1; j > i; j--) {
        String one = newdt.get(i).getTask_id();
        String two = newdt.get(j).getTask_id();
        if (two.equals(one)) {
            newdt.remove(j);
        }
    }
}