Java 8 : Predicates

Java 8 : Predicates

December 21, 2019


Predicate Example to find out all the even numbers in the given array.


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package com.blogspot.ekumeedkiasha;

import java.util.function.Predicate;

/*
 * find out all the even numbers in the given array
 */
public class PredicateExample2 {

 public static void main(String[] args) {

  int[] num = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

  Predicate<Integer> even = x -> x % 2 == 0;

  for (int i : num) {
   if (even.test(i)) {
    System.out.println(i);
   }
  }

 }

}




Predicate Joining Example:  

Interface predicate has three default methods.

1. and(Predicate p)
2. or(Predicate p)
3. negate()

find out all the even numbers which are greater than 5 in the given array.

 
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package com.blogspot.ekumeedkiasha;

import java.util.function.Predicate;

/*
 * Q1. Find out all the even numbers in the given array.
 * 
 * Q2. Find out all the number which is greater than 5 in the given array.
 */
public class PredicateExample2 {

 public static void main(String[] args) {

  int[] num = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

  Predicate<Integer> even = x -> x % 2 == 0;

  Predicate<Integer> grt = y -> y > 5;

  for (int i : num) {
   if (grt.or(even).test(i)) {
    System.out.println(i);
   }

}

}

}


For equality predicate interface has isEqual(Object o) method which is static.

Example: 
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package com.blogspot.ekumeedkiasha;

import java.util.function.Predicate;

public class PredicateExample3 {

 public static void main(String[] args) {
  Predicate<String> name = Predicate.isEqual("Mumbai");
  System.out.println(name.test("Mumbai"));
 }

}

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