Delete duplicate lines from a String in Java

My string is:

"EEE
EEE
AAA
BBB
CCC
BBB
DDD
CCC"

But I need to without same lines this string. Like this:

"EEE
AAA
BBB
CCC
DDD"

How can I do it?

Considering you string being stored in String s, how about

String[] tokens = s.split("\n");
StringBuilder resultBuilder = new StringBuilder();
Set<String> alreadyPresent = new HashSet<String>();

boolean first = true;
for(String token : tokens) {

    if(!alreadyPresent.contains(token)) {
        if(first) first = false;
        else resultBuilder.append("\n");

        if(!alreadyPresent.contains(token))
            resultBuilder.append(token);
    }

    alreadyPresent.add(token);
}
String result = resultBuilder.toString();

or:

Set<String> tokens = new HashSet<String>(Arrays.asList(s.split("\n")));
StringBuilder resultBuilder = new StringBuilder();

boolean first = true;
for(String token : tokens) {
    if(first) first = false;
    else resultBuilder.append("\n")

    resultBuilder.append(token);
}

String result = resultBuilder.toString();