You verify if an object is an instance of a particular class. You usually apply it, when you have a recommendation or parameter to an object that is of a superclass or interfaces standard and demands to know whether the original object has unusual another type (usually more concrete).
Example:
public void doSomething(Number param) {
if( param instanceof Double) {
System.out.println("param is a Double");
}
else if( param instanceof Integer) {
System.out.println("param is an Integer");
}
if( param instanceof Comparable) {
//subclasses of Number like Double etc. implement Comparable
//other subclasses might not -> you could pass Number instances that don't implement that interface
System.out.println("param is comparable");
}
}
Remark that if you ought to work that operator very frequently it is usually a hint that your plan has some flaws. So in a well-designed application, you should use that operator as concise as feasible (of the way there are limitations to that common rule).
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