The Angle Bracket in Java

1. Angle Bracket(<>) in Java
2. Usage of Angle Bracket(<>) in Built-In Data Types in Java

The Angle Bracket is used to define the Generics in Java. Generic is a way to parameterize a class, method, or interface.

For example, the types like Arraylist, HashMap and Hashset use generics. Generics can also be used for any type.

This tutorial demonstrates what is an Angle Bracket(<>) in Java and how to use it.

Angle Bracket(<>) in Java

Let’s have an example; we have a class named Delftstack which will accept unspecified object types. Then there is a field EmployeeSalary, which will also accept any object type.

Finally, we declare a parameterized constructor to print the employee salary. That is on the user to decide if the salary is an integer, float, double or string etc.

Code:

package delftstack;

public class Delftstack<T> {
  T EmployeeSalary;

  public Delftstack(T EmployeeSalary) {
    this.EmployeeSalary = EmployeeSalary;
  }

  public void print() {
    System.out.println("The Employee Salary is: " + this.EmployeeSalary);
  }
  public static void main(String[] args) {
    int EmployeeSalary = 1000;
    Delftstack Demo = new Delftstack(EmployeeSalary);
    Demo.print();
  }
}

The code above uses the <T> with the class name. We can use anything instead of T here.

Output:

The Employee Salary is: 1000

As mentioned, <T> is used for any type. There are also some other generic terms for a specific type, and these terms are described in the following.

1. <T> is referred to as any type.
2. <E> is referred to as element type.
3. <N> is referred to as number type.
4. <V> as referred to as value.
5. <K> as referred to as a key.

A few important benefits of using generics <> in Java are stated below.

• Reusability: We can use the generic method, class of interface multiple times because we apply the object type based on the task we are trying to achieve.
• Better output: If we use an Object type that is different from the one we specified, the compiler will tell us on time.
• Great with Data Structures: The generics work great with data structures, for example, the Arraylist or Hashmap.

Usage of Angle Bracket(<>) in Built-In Data Types in Java

As mentioned above <> is also used in built-in classes like ArrayList, HashMap, and HashSet. Let’s try an example with these three data types.

Code:

package delftstack;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;

public class Delftstack<T> {
  public static void main(String[] args) {
    ArrayList<String> Demo_List = new ArrayList<String>();
    Demo_List.add("Delftstack1");
    Demo_List.add("Delftstack2");
    Demo_List.add("Delftstack3");
    System.out.println(Demo_List);

    HashMap<String, Integer> Demo_Map = new HashMap<String, Integer>();
    Demo_Map.put("Jack", 1000);
    Demo_Map.put("Mike", 1500);
    Demo_Map.put("Michelle", 1800);
    System.out.println(Demo_Map);

    HashSet<String> Demo_Set = new HashSet<String>();
    Demo_Set.add("Delftstack1");
    Demo_Set.add("Delftstack2");
    Demo_Set.add("Delftstack3");
    System.out.println(Demo_Set);
  }
}

The Angle Bracket(<>) defines data types for ArrayList, HashMap, and HashSet.

Output:

[Delftstack1, Delftstack2, Delftstack3]
{Michelle=1800, Mike=1500, Jack=1000}
[Delftstack1, Delftstack2, Delftstack3]