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
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
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
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)
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:
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
Do you like this Post? – then check my other helpful posts:
- Passing Function as a Parameter in another Method in Java 8
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