Exceptions which extend RuntimeException class are known as UnChecked Exceptions. We are not supposed to write the statements (for which we expect UnChecked exception) under try...catch block. ArithmeticException and NullPointerException are some examples of UnChecked exception.

Java Code: 
String [] str = new String[5];
str[5] = "Java Tip";
UnChecked/Runtime exception reported:

Java Code: 
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 5