What causes class cast exception?

ClassCastException is a runtime exception raised in Java when we try to improperly cast a class from one type to another. It’s thrown to indicate that the code has attempted to cast an object to a related class, but of which it is not an instance.

Why do we get ClassCastException in TreeSet?

This error is thrown by TreeSet because TreeSet is used to store elements in sorted order and if the specified element cannot be compared with the elements currently in the set then TreeSet won’t be able to store elements in sorted order and hence, TreeSet throws class cast exception.

What is class cast exception in Java?

ClassCast Exception in Java is one of the unchecked exceptions that occur when we try to convert one class type object into another class type. ClassCast Exception is thrown when we try to cast an object of the parent class to the child class object.

Why heterogeneous objects are not allowed in TreeSet?

TreeSet does not allow to insert heterogeneous objects because it must compare objects to determine sort order. TreeSet is not synchronized. If multiple threads access a hash set concurrently, and at least one of the threads modifies the set, it must be synchronized externally.

What is class cast?

Class class is used to cast the specified object to the object of this class. The method returns the object after casting in the form of an object. Syntax: public T[] cast(Object obj)

How do you stop ClassCastException?

Be careful when trying to cast an object of a class into another class. Ensure that the new type belongs to one of its parent classes. You can prevent the ClassCastException by using Generics, because Generics provide compile time checks and can be used to develop type-safe applications.

How do you solve ClassCastException?

In order to deal with ClassCastException be careful that when you’re trying to typecast an object of a class into another class ensure that the new type belongs to one of its parent classes or do not try to typecast a parent object to its child type.

What is Java comparable interface?

The Java Comparable interface, java. lang. Comparable , represents an object which can be compared to other objects. For instance, numbers can be compared, strings can be compared using alphabetical comparison etc. Several of the built-in classes in Java implements the Java Comparable interface.

How do you find class cast exception?

It’s really pretty simple: if you are trying to typecast an object of class A into an object of class B, and they aren’t compatible, you get a class cast exception.

Why TreeSet does not allow null?

The reason is, if you look at the internal implementation of the TreeSet, it uses natural ordering, that means TreeSet uses Comparable interface by default to sort its value by comparing other value. …

What is difference between SortedSet and TreeSet?

It also implements NavigableSet interface. NavigableSet extends SortedSet and Set interfaces….Java.

How do you cast a class?

Upcasting is casting a subtype to a super type in an upward direction to the inheritance tree. It is an automatic procedure for which there are no efforts poured in to do so where a sub-class object is referred by a superclass reference variable. One can relate it with dynamic polymorphism.