Supplier Interface is a part of the java.util.function package which is introduced in Java 8. It is an in-built Functional Interface. This function doesn’t expect any input but produces an output in the form of a value of type T. In this post, we are going to see several implementations of Supplier Interface by using different examples.
Supplier Interface in Java 8 Examples...!!! Share on X
Look at Supplier Javadoc description below:
As you’ve seen in the above screenshot, Supplier Interface contains only the following function:
T get();
This signifies that this method doesn’t take any argument as an input but produces an output value of type T.
Several Implementations of Supplier Interface in Java 8...!!! Share on X
Let’s begin:
Example 1. Supplier resulting a string value
1 2 3 4 5 6 7 8 9 10 11 12 13 | import java.util.function.Supplier; public class SupplierInterfaceJava8Example1 { public static void main(String args[]) { System.out.println("Ex. 1 - Java 8 Supplier Interface\n"); Supplier <String> simpleString = () -> "Hello Basic Supplier"; System.out.println(simpleString.get()); } } |
Example 2. Supplier resulting a HashMap
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | import java.util.HashMap; import java.util.function.Supplier; public class SupplierInterfaceJava8Example2 { public static void main(String[] args) { System.out.println("Ex. 2 - Java 8 Supplier Interface\n"); HashMap <Integer, String> personHashMap = new HashMap <Integer, String> (); personHashMap.put(19, "Isha"); personHashMap.put(43, "Gaurangee"); personHashMap.put(4, "Yashika"); Supplier <HashMap <Integer, String>> supplierPersonObj = () -> personHashMap; printMap(supplierPersonObj); } public static void printMap(Supplier < HashMap < Integer, String >> supplierObj) { System.out.println(supplierObj.get()); } } |
Example 3. Supplier resulting an ArrayList using Stream API
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | import java.util.ArrayList; import java.util.List; import java.util.function.Supplier; public class SupplierInterfaceJava8Example3 { public static void main(String[] args) { System.out.println("Ex. 3 - Java 8 Supplier Interface\n"); List <String> studentNames = new ArrayList <String> (); studentNames.add("Yogi"); studentNames.add("Yash"); studentNames.add("Yashika"); studentNames.add("Pulkit"); studentNames.add("Noni"); studentNames.add("Isha"); studentNames.add("DV"); studentNames.stream().forEach((item) -> { printName(() -> item); }); } public static void printName(Supplier <String> supplier) { System.out.println(supplier.get()); } } |
Example 4. Supplier resulting a custom Class object (like ‘Students’ in this case)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | import java.util.function.Supplier; import org.personal.samples.Students; public class SupplierInterfaceJava8Example4 { public static void main(String[] args) { System.out.println("Ex. 4 - Java 8 Supplier Interface\n"); Supplier <Students> supplierStudentObj = () -> { return new Students(25, "Isha Durani"); }; System.out.println("Student details: \n" + "Name: " + supplierStudentObj.get().getName() + "\nAge: " + supplierStudentObj.get().getAge()); } } |
Students Class:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | public class Students { int age; String name; public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Students() {} public Students(int age, String name) { this.age = age; this.name = name; } } |
Java 8 Supplier Interface is an absolute useful addition as part of ‘Functional Interfaces’ and can serve variety of purposes. It is quite powerful as it can be used as a higher order functions through lambda functions and above examples could help you to get better idea on how to implement it.
Supplier Interface in Java 8 Examples...!!! Share on X
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