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:
| temperature t | message |
| 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");
Observations:
(20 < temp) && (temp <= 30), since it appears in the else-branch of
the first condition. Hence, we already know that (temp <= 30) is
true.