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How to use Consumer and BiConsumer interfaces in lambda expression in Java?
A Consumer interface is a predefined functional interface that can be used when creating lambda expressions or method references. This interface represents an operation that accepts a single input parameter and doesn't return anything. It contains only one method named accept(). The BiConsumer interface is similar to a Consumer interface and accepts two input parameters and doesn’t return anything.
Syntax
@FunctionalInterface public interface Consumer<T> @FunctionalInterface public interface BiConsumer<T, U>
Example
import java.util.*;
import java.util.function.*;
public class ConsumerBiConsumerTest {
public static void main(String[] args) {
Consumer<String> c = (x) -> System.out.println(x.toLowerCase()); // lambda expression
c.accept("Raja");
Consumer<Integer> con = (x) -> { // lambda expression
System.out.println(x + 10);
System.out.println(x - 10);
};
con.accept(10);
BiConsumer<Strng, String> bc = (x, y) -> { System.out.println(x + y);};
bc.accept("1", "2");
List<Person> plist = Arrays.asList(new Person("RAJA"), new Person("ADITHYA"));
acceptAllEmployee(plist, p -> System.out.println(p.name));
acceptAllEmployee(plist, p -> {p.name = "unknown";});
acceptAllEmployee(plist, p -> System.out.println(p.name));
}
public static void acceptAllEmployee(List<Person> plist, Consumer<P> con) {
for(Person p : plist) {
con.accept(p);
}
}
}
// Person class
class Person {
public String name;
public Person(String name) {
this.name = name;
}
}Output
raja 20 0 12 RAJA ADITHYA unknown unknown
Updated on: 13-Jul-2020
2K+ Views
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