String manipulation - split ()

All the answers are correct, but I find it interesting to add that, taking into account that the surname will always be the last word of string , you can do the following:

String nome = "Dan Lucio Prada";
EscreverSobrenome(nome); // A saída será "Prada"

String nome2 = "Joaquim Pedro Soares da Silva";
EscreverSobrenome(nome2); // A saída será "Silva"

public String EscreverSobrenome(String nome){
    sobrenome = nome.split(" ")[nome.split(" ").length - 1]; // Essa linha é a solução pro seu problema
    System.out.println(sobrenome);
}

In this way no matter how many words you have, the variable sobrenome will always receive the last word.

Have, do so:

String nome = "Dan Lucio Prada";
String sobronome = nome.split(" ")[2];

Of course this only works if the name has 3 words.

For registration and (perhaps) usefulness to someone, in this case there is no need to have to do split of string . I do not know if it is mandatory to use split or have the last name, but without using split it is possible to do it in a single line, something like this:

sentence.substring(sentence.lastIndexOf(" ") + 1)

sentence.lastIndexOf(" ") , as it is simply understood, will return the index of the last space in the statement. Then we add 1 , position of the next letter that is the first letter of the last name. With this information substring(int beginIndex) , you'll start of this first letter of the name and will go to the end of the sentence / name, always returning the last word.

For example, this:

public static void main(final String[] args) {
    final String dan = "Dan Lucio Prada";
    System.out.println(lastWordFromSentence(dan));

    final String bruno = "Bruno César";
    System.out.println(lastWordFromSentence(bruno));

    final String name = "Bruno";
    System.out.println(lastWordFromSentence(name));
}

public static String lastWordFromSentence(final String sentence) {
    return sentence.substring(sentence.lastIndexOf(" ") + 1);
}

Generate this result:

Prada
César
Bruno

It is suggested in cases that the use of split is not mandatory:)

Yes, you can do this on a line:

System.out.println("Dan Lucio Prada".split(" ")[2]);

But it's much better to use more than one line and do it right:

String nome = "Dan Lucio Prada";
String[] partes = nome.split(" ");
System.out.println(partes[partes.length - 1]);

You can even do this in a row too but it's inefficient, so you'd better do it right.

See running on ideone .