How the braces makes our 'if' statement clearer?

If there is only one statement in an if or else block, the braces are optional.

public class MainClass {

public static void main(String[] args) {
int a = 3;
if (a > 3)
a++;
else
a = 3;
}

}

Consider the following example:

public class MainClass {

public static void main(String[] args) {
int a = 3, b = 1;

if (a > 0 || b < 5)
  if (a > 2)
    System.out.println("a > 2");
  else
    System.out.println("a < 2");

}

}