In this article, we will discuss Stream’s anyMatch() method in details with examples
Read below methods which are similar to anyMatch() method
1. Stream anyMatch() method :
- This Stream method is a terminal operation which returns true for the provided Predicate, otherwise returns false
- In other words, anyMatch() method returns true if at least any one of the element of the original Stream satisfies the provided Predicate condition, else false
- Stream’s anyMatch() method is stateless which means it is non-interfering with other elements in the stream
- May not evaluate the predicate on all elements if not necessary for determining the result
- It is a short-circuiting terminal operation, as Stream pipeline ends on the first match of the provided Predicate
- If the stream is empty then false is returned and the predicate is not evaluated
- Method signature :- boolean anyMatch(Predicate<? super T> predicate)
2. Stream anyMatch() method examples :
2.1 To find specific element present or not
- First list contains integers numbers
- For integer list, we are applying Predicate condition to find if there is any number greater than 9 and 10 and it returns true for 1st condition and false for second condition
- Second list contains String elements and we are trying to find specific element by providing Predicate condition
- anyMatch() returns true for the satisfied condition if at least one element is present in the given Stream
package net.bench.resources.stream.anymatch.example;
import java.util.Arrays;
import java.util.List;
public class StreamAnyMatchMethod {
public static void main(String[] args) {
// 1. list of 10 natural numbers
List<Integer> numbers = Arrays
.asList(1,2,3,4,5,6,7,8,9,10);
// 1.1 predicate to find number greater than 9
boolean bool1 = numbers
.stream()
.anyMatch(num -> num > 9);
// 1.2 print to console
System.out.println("Original list of integers : " + numbers);
System.out.println("\nWhether integer list contains"
+ " number greater than 9 = " + bool1);
// 1.3 in line Predicate condition
System.out.println("Whether integer list"
+ " contains number greater than 10 = "
+ numbers.stream()
.anyMatch(num -> num > 10));
// 2. list of 5 Strings
List<String> sectors = Arrays.asList(
"Motor",
"Power",
"Steel",
"Chemicals",
"Capital"
);
// 2.1 predicate to find whether String element present or Not
boolean bool2 = sectors
.stream()
.anyMatch(str -> str.contains("Power"));
// 2.2 print to console
System.out.println("\n\nOriginal list of Strings : " + sectors);
System.out.println("\nWhether String list contains"
+ " element 'Power' = " + bool2);
// 2.3 in line Predicate condition
System.out.println("Whether String list contains"
+ " element 'Consumer' = "
+ sectors.stream()
.anyMatch(str -> str.contains("Consumer")));
}
}
Output:
Original list of integers : [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Whether integer list contains number greater than 9 = true
Whether integer list contains number greater than 10 = false
Original list of Strings : [Motor, Power, Steel, Chemicals, Capital]
Whether String list contains element 'Power' = true
Whether String list contains element 'Consumer' = false
2.2 To find Student from multiple Predicates
- A Student POJO is defined with 3 attributes
- A list contains 5 Student objects defining their attributes like rollNumber, name, and age
- We have defined 2 simple Predicate namely p1 and p2 and one more joined Predicate which is the combined Predicate of p1 && p2
- 1st Predicate – find Student whose name starts with ‘K // returns true
- 2nd Predicate – find Student with Age greater than 22 // returns true
- 3rd Predicate – Student whose name starts with ‘K‘ and their Age is greater than 22 // returns false
- inline Predicate – Student whose name starts with ‘V‘ and their Age is less than 18 // returns true
Student.java
package net.bench.resources.stream.anymatch.example;
public class Student {
// member variables
private int rollNumber;
private String name;
private int age;
// constructors
public Student(int rollId, String name, int age) {
super();
this.rollNumber = rollId;
this.name = name;
this.age = age;
}
// getters & setters
public int getRollId() {
return rollNumber;
}
public void setRollId(int rollId) {
this.rollNumber = rollId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
// toString()
@Override
public String toString() {
return "Student [rollNumber=" + rollNumber
+ ", name=" + name
+ ", age=" + age
+ "]";
}
}
StreamAnyMatchMethodForStudents.java
package net.bench.resources.stream.anymatch.example;
import java.util.Arrays;
import java.util.List;
import java.util.function.Predicate;
import net.bench.resources.stream.min.max.example.Student;
public class StreamAnyMatchMethodForStudents {
public static void main(String[] args) {
// list of students
List<Student> students = Arrays.asList(
new Student(1, "Viraj", 17),
new Student(2, "Krishnanand", 18),
new Student(3, "Rishi", 16),
new Student(4, "Suresh", 23),
new Student(5, "Aditya", 21)
);
// predicate 1 - name starts with K
Predicate<Student> p1 = stud -> stud.getName().startsWith("K");
// predicate 2 - age older than 22
Predicate<Student> p2 = stud -> stud.getAge() > 22;
// combined predicate - p1 && p2
Predicate<Student> p3 = p1.and(p2);
// print all Students to console
System.out.println("List of Students :-");
students.stream().forEach(student -> System.out.println(student));
// 1. find whether any Student name starts with 'K'
boolean boolP1 = students.stream().anyMatch(p1);
System.out.println("\n1. Whether Student whose name starts"
+ " with 'K' present ? " + boolP1);
// 2. find whether any Student name starts with 'K'
boolean boolP2 = students.stream().anyMatch(p2);
System.out.println("\n2. Student with Age greater"
+ " than 22 present ? " + boolP2);
// 3. Student Name starts with 'K' && Age greater than 22
boolean boolP3 = students.stream().anyMatch(p3);
System.out.println("\n3. Student Name starts with 'K' and"
+ " Age greater than 22 present ? " + boolP3);
// 4. in line multiple Predicate condition
boolean boolP4 = students.stream().anyMatch(
stud -> (stud.getName().startsWith("V") && stud.getAge() < 18));
System.out.println("\n4. Student Name starts with 'V' "
+ "and Age greater than 18 present ? " + boolP4);
}
}
Output:
List of Students :-
Student [rollNumber=1, name=Viraj, age=17]
Student [rollNumber=2, name=Krishnanand, age=18]
Student [rollNumber=3, name=Rishi, age=16]
Student [rollNumber=4, name=Suresh, age=23]
Student [rollNumber=5, name=Aditya, age=21]
1. Whether Student whose name starts with 'K' present ? true
2. Student with Age greater than 22 present ? true
3. Student Name starts with 'K' and Age greater than 22 present ? false
4. Student Name starts with 'V' and Age greater than 18 present ? true
References:
- https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Collection.html
- https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html
Happy Coding !!
Happy Learning !!
