Arquivo Discussoes de Programacao e Tecnologia Hi folks,
I will take the opportunity to leave some questions that for sure will make your heads crazy, let’s go !!
here is the first one:
what happens with this code ?
class TestClass
{
int i;
public TestClass(int i) { this.i = i; }
public String toString()
{
if(i == 0) return null;
else return “”+i;
}
public static void main(String[ ] args)
{
TestClass t1 = new TestClass(0);
TestClass t2 = new TestClass(2);
System.out.println(t2);
System.out.println(""+t1);
}
}
se não to enganado
2
null
ou então
2
<linah em branco>
só se eu testar qui para ter certeza 
Vai imprimir isso:
2
null
Mas, afinal, qual o problema com esse codigo?
what numbers will be printed by this sample?
look twice, before answer, there is a trap below 
public class ForSwitch
{
public static void main(String args[])
{
char i;
LOOP: for (i=0;i<5;i++)
{
switch(i++)
{
case ‘0’: System.out.println(“A”);
case 1: System.out.println(“B”); break LOOP;
case 2: System.out.println(“C”); break;
case 3: System.out.println(“D”); break;
case 4: System.out.println(“E”);
case ‘E’ : System.out.println(“F”);
}
}
}
}