public void HolaMundo(){
   System.out.println("Hola mundo");
}

HolaMundo();

public void Imprimir(String algo){
       System.out.println(algo);
    }

Imprimir("Hola mundo");

public String Mayusculas(String minúsculas){
           return minúsculas.toUpperCase();
        }

System.out.println(Mayusculas("hola mundo"));

String mayusculas=Mayusculas("hola mundo);