Generics in java were introduced as one of features in JDK 5.
generics sole purpose i.e. Type Safety.
Generic types are instantiated to form parameterized types by providing actual type arguments that replace the formal type parameters. A class like LinkedList<E> is a generic type, that has a type parameter E . Instantiations, such as LinkedList<Integer> or a LinkedList<String>, are called parameterized types, and String and Integer are the respective actual type arguments.
If you closely look at java collection framework classes then you will observe that most classes take parameter/argument of type Object and return values from methods as Object. Now, in this form, they can take any java type as argument and return the same. They are essentially heterogeneous i.e. not of a particular similar type.
In original collection framework, having homogeneous collections was not possible without adding extra checks before adding some checks in code. Generics were introduced to remove this limitation to be very specific. They add this type checking of parameters in your code at compile time, automatically. This saves us writing a lot of unnecessary code which actually does not add any value in run-time, if written correctly.
Without this type safety, your code could have infected by various bugs which get revealed only in runtime. Using generics, makes them highlighted in compile time itself and make you code robust even before you get the bytecode of your java source code files.
In the heart of generics is “type safety“. What exactly is type safety? It’s just a guarantee by compiler that if correct Types are used in correct places then there should not be any ClassCastException in runtime.
Another important term in java generics is “type erasure“. It essentially means that all the extra information added using generics into source code will be removed from bytecode generated from it. Inside bytecode, it will be old java syntax which you will get if you don’t use generics at all. This necessarily helps in generating and executing code written prior java 5 when generics were not added in language.
generics sole purpose i.e. Type Safety.
Generic types are instantiated to form parameterized types by providing actual type arguments that replace the formal type parameters. A class like LinkedList<E> is a generic type, that has a type parameter E . Instantiations, such as LinkedList<Integer> or a LinkedList<String>, are called parameterized types, and String and Integer are the respective actual type arguments.
If you closely look at java collection framework classes then you will observe that most classes take parameter/argument of type Object and return values from methods as Object. Now, in this form, they can take any java type as argument and return the same. They are essentially heterogeneous i.e. not of a particular similar type.
In original collection framework, having homogeneous collections was not possible without adding extra checks before adding some checks in code. Generics were introduced to remove this limitation to be very specific. They add this type checking of parameters in your code at compile time, automatically. This saves us writing a lot of unnecessary code which actually does not add any value in run-time, if written correctly.
Without this type safety, your code could have infected by various bugs which get revealed only in runtime. Using generics, makes them highlighted in compile time itself and make you code robust even before you get the bytecode of your java source code files.
In the heart of generics is “type safety“. What exactly is type safety? It’s just a guarantee by compiler that if correct Types are used in correct places then there should not be any ClassCastException in runtime.
Another important term in java generics is “type erasure“. It essentially means that all the extra information added using generics into source code will be removed from bytecode generated from it. Inside bytecode, it will be old java syntax which you will get if you don’t use generics at all. This necessarily helps in generating and executing code written prior java 5 when generics were not added in language.
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