A common use of nested if's is when the conditions in the nested if's are mutually excluding, i.e., no two of them can be simultaneously true.
Example: Based on the value of the temperature (an integer) print a message according to the following table:
|30 < t||hot|
|20 < t < = 30||warm|
|10 < t < = 20||fine|
|t < = 10||cold|
int temp; ... if (30 < temp) System.out.println("hot"); else if (20 < temp) System.out.println("warm"); else if (10 < temp) System.out.println("fine"); else System.out.println("cold");
(20 < temp) && (temp <= 30), since it appears in the else-branch of the first condition. Hence, we already know that (temp <= 30) is true.