Why is casting necessary in java

This leads into java. ClassCastException , when we try to type, cast the second object, which is an Integer, into String. This problem can be avoided b y usin g Generics in Java which we will see in next section. You can also perform casting with primitive data types e.

This is known as down-casting in Java. See these core Java online courses for more details on type casting of primitive and reference type in Java.

Generics and Type Casting in Java. Generics was introduced in Java 5 along with another type-saf e feat ure Enum , whic h en sures type safety of code during compile time, So rather you getting ClassCastException during runtime by type casting you get compile timer error why your code violates type safety.

Use of Generics also removes casting from many places e. Here is the modified version of same code which is free of ClassCastException b ecau se of the use of Generics :.

If you are new to Generics, those angle bracket denotes type. In this Java tutorial, we learn What is type casting in Java , how to cast one class to another class or interface in Java with a simple type casting Example. We have also seen the risk of ClassCastException related to type casting and How can we reduce that risk by using Generics in Java. In Summary, minimize type casting in Java program and use type-safe Enum and Generics to reduce or completely eliminate type casting from Java code.

Share to Twitter Share to Facebook. Labels: coding , core java , object oriented programming. Anonymous, you are right. Thanks for pointing it out. February 6, at AM Anonymous said February 3, at PM P. Rakesh Sharma said June 11, at AM Anonymous said You can not access them with any other type December 11, at PM Unknown said Can anyone explain about ClassCastException in detail please March 15, at AM javin paul said March 18, at AM Swanandd said December 15, at AM.

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Dart Hell In the example above, we converted the double data type into an int data type. The decimal part of the value is lost after type casting. To convert a primitive data type into an object, we need the wrapper classes.

We can take string inputs from the users e. For example:. In Java, all primitive wrapper classes are immutable i. We can cast an int to double data type by passing the value of int to the constructor of the Double wrapper class.

In this method, we convert int to double using the valueOf method in the Double wrapper class. In this article, we have looked at the different ways of type casting our data type.

We can now easily type cast from one data type to another. Terrypha is an undergraduate computer science student at Meru university. She is passionate about computer programing, Machine Learning, and Artificial Intelligence. She is open to research and collaborations. Discover Section's community-generated pool of resources from the next generation of engineers.

The simple, flexible deployment options your customers expect with the low overhead your team craves. The advantages of Java features such as portability, scalability, and platform independence largely arise from the basic functionalities of Java.

The following discussion would aim at exploring the different types of casting, such as upcasting and downcasting in Java. Furthermore, the discussion would also focus on exploring the necessity, benefits, and rules of casting. The start of a good tutorial on casting in Java should always start with a definition of the term.

Casting involves taking one object of a specific type and transforming it into another object type. This is one of the prominent reasons for which you can find casting and conversion as analogous processes in Java. You should note that casting is not specific only to Java because many other programming languages also support the casting of variable types.

However, Java has certain restrictions for casting variables so that you cannot cast any variable to a random type. Therefore, you need to focus on java casting rules for understanding the best ways for casting.

One of the foremost rules is evident in the casting of classes and interfaces in the same type of hierarchy into each other. The casting of two objects without a similar type of hierarchy could result in a compile-time error. Another important consequence of Java casting rules is evident in typecasting objects in a similar type hierarchy, albeit with the difference in the type of the object that you are casting and the object on which you are casting.

The outcome of this deviation would be the ClassCastException in Java. The release of Java SE 11 has come up with a number of new features. One of the foremost concerns related to casting in Java refers directly to the two type groups in Java.

The two types of groups are primitive and reference. The first attention of this discourse would go to the casting of primitives to ensure type conversion. The primitives refer to int, double, float, long, and other data types. On the other hand, references include type classes, arrays, or interfaces.

However, one of the important points related to casting in Java refers to implicit and explicit changes. In certain cases, the system could itself change the type of expression based on certain requirements. Take the following example into consideration,.

Also Check: Java 11 Features. The next important point of concern arises with explicit casting, which is also known as type casting in Java.

The programmer has to specify the type in which an object should be cast if certain changes do not happen automatically. The basic syntax for type casting is as follows,.

Continuing ahead with the narrowing and widening of primitives, it becomes easier to develop an overall understanding of casting in Java. Widening of primitive types or upscaling involves conversion from a smaller primitive to a larger destination primitive. In the course of widening primitives, smaller primitive value assumes the larger container leaving lots of extra space. As a result, the space on the left is filled with zeros, and you could then proceed towards the floating-point from the integer group.

Take the following example to understand the widening of primitives in Java typecasting. The above example is feasible because the movement to a wider primitive does not result in loss of information.

Simply, the widening of primitives explains the basics of upcasting in Java. Narrowing primitives is also another form of casting in which you fit a large value than the type specified in variable declaration. As a result, information loss is imperative due to discarding some bytes. Narrowing primitives also demands explicit expression about the use of a cast, and it provides a basic idea about downcasting in Java.

Take a look at the following example to understand it better. Now, let us focus on the two types of casting, i. Upcasting involves casting to a supertype, while downcasting refers to casting to a subtype.