When do we use the variable argument in Java?

Variable arguments are very useful. Many methods use variable arguments for handling when the number of parameters is uncertain. One good example is the String.format method. This method accepts multiple parameters.

String.format("This is an integer: %d", myInt);
String.format("This is an integer: %d and a string: %s", myInt, myString);

Like this. Instead, you'll have to set some rules and make them throw errors when they go against the rules.