Java 8 – Find Longest String in an Arrays or List or Stream ?

July 2, 2022 SJ Collection, Java 8 0

In this article, we will discuss how to find longest String in an Arrays and List using Java 1.8 version

1. Finding Longest String in List or ArrayList :

We will find Longest String in a List or ArrayList using different methods of Java 8 Stream

  • Using Stream.max() method
  • Using Stream.collect() method
  • Using Stream.reduce() method
  • Using Stream.sorted() method
  • Using IntStream.summaryStatistics() method
  • Using Collection.max() method

1.1 Using Stream.max() method

  • Stream.max() method allows to get maximum value from the processing Stream elements by passing java.util.Comparator as argument
  • In the below illustration we used different Comparators as method-reference to max() method,
    • Comparator.comparingInt(String::length) for finding Longest String from List
    • Integer::compare for finding length of Longest String
  • Stream.max() method returns Optional<T>
    • get() method of Optional<T> returns longest String from the List or ArrayList
  • Finally, printing longest String and its length to the console

FindLongestStringInListUsingJava8StreamMaxMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

public class FindLongestStringInListUsingJava8StreamMaxMethod {

	public static void main(String[] args) {

		// 1. names with different length
		List<String> names = Arrays.asList(
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
				);


		// 1.1 print to console=
		System.out.println("Original String List :- \n" + names);


		// 2. find Longest name in List using max(Integer::compare).get()
		String longestString = names
				.stream()
				.max(Comparator.comparingInt(String::length))
				.get();
		System.out.println("\nLongest String is = " 
				+ longestString);


		// 2.1 find Length of Longest name in List using max(Integer::compare).get()
		int lengthOflongestString = names
				.stream()
				.map(String::length)
				.max(Integer::compare)
				.get();
		System.out.println("\nLength of Longest String is = " 
				+ lengthOflongestString);
	}
}

Output:

Original String List :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

1.2 Using Stream.collect() method

  • Stream.collect() method accepts java.util.stream.Collectors as argument
  • Collectors class has many useful methods to get maximum value from the processing Stream elements like
    • Collectors.maxBy() for finding Longest String from List
    • Collectors.summarizingInt() for finding length of Longest String
  • Collectors.maxBy() accepts Comparator.comparingInt(String::length) as method-argument and returns Optional<T>
    • get() method of Optional<T> returns longest String from the List or ArrayList
  • Collectors.summarizingInt() accepts String::length as method-reference and returns IntSummaryStatistics
    • getMax() method of IntSummaryStatistics returns length of the longest String from the List or ArrayList
  • Finally, printing longest String and its length to the console

FindLongestStringInListUsingJava8StreamCollectMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

public class FindLongestStringInListUsingJava8StreamCollectMethod {

	public static void main(String[] args) {

		// 1. names with different length
		List<String> names = Arrays.asList(
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
				);


		// 1.1 print to console
		System.out.println("Original String List :- \n" + names);


		// 2. find Longest name using collect(Collectors.maxBy(Comparator.comparingInt(String::length)))
		String longestStr = names
				.stream()
				.collect(Collectors.maxBy(Comparator.comparingInt(String::length)))
				.get();
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find length of Longest name using collect(Collectors.summarizingInt(String::length))
		int lengthofLongestStr = names
				.stream()
				.collect(Collectors.summarizingInt(String::length))
				.getMax();
		System.out.println("\nLength of Longest String is = " + lengthofLongestStr);
	}
}

Output:

Original String List :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

1.3 Using Stream.reduce() method

  • Stream.reduce() method accepts BinaryOperator to get maximum value from the processing Stream elements by passing lambda-expression as argument
  • In the below illustration we used different lambda-expression to reduce() method,
    • Lambda expression :- (x, y) -> x.length() > y.length() ? x : y for finding Longest String from List
    • Lambda expression :- (x, y) -> Integer.max(x, y) for finding length of Longest String
  • Stream.reduce() method returns Optional<T>
    • get() method of Optional<T> returns longest String from the List or ArrayList
  • Finally, printing longest String and its length to the console

FindLongestStringInListUsingJava8StreamReduceMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.List;

public class FindLongestStringInListUsingJava8StreamReduceMethod {

	public static void main(String[] args) {

		// 1. names with different length
		List<String> names = Arrays.asList(
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
				);


		// 1.1 print to console
		System.out.println("Original String List :- \n" + names);


		// 2. find Longest String using .reduce((x, y) -> x.length() > y.length() ? x : y).get()
		String longestStr = names
				.stream()
				.reduce((x, y) -> x.length() > y.length() ? x : y)
				.get();
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find Length of Longest String using .reduce((x, y) -> Integer.max(x, y)).getAsInt();
		int lengthOfLongestStr = names
				.stream()
				.mapToInt(String::length)
				.reduce((x, y) -> Integer.max(x, y))
				.getAsInt();
		System.out.println("\nLength of Longest String is = " + lengthOfLongestStr);
	}
}

Output:

Original String List :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

1.4 Using Stream.sorted() method

  • Stream.sorted() method sorts String list on the basis of String length
  • In the below illustration we are passing lambda-expression to sorted() method to sort according to String length with
    • higher length String element at the top
    • lower length String element at the bottom
  • findFirst() method returns 1st String which has highest length in the String list and it returns Optional<T>
    • get() method of Optional<T> returns longest String from the List or ArrayList
  • Finally, printing longest String and its length to the console

FindLongestStringInListUsingJava8StreamSortedMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.List;

public class FindLongestStringInListUsingJava8StreamSortedMethod {

	public static void main(String[] args) {

		// 1. names with different length
		List<String> names = Arrays.asList(
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
				);


		// 1.1 print to console
		System.out.println("Original String List :- \n" + names);


		// 2. find Longest name using .sorted((str1, str2) -> str1.length() > str2.length() ? -1 : 1)
		String longestStr = names
				.stream()
				.sorted((str1, str2) -> str1.length() > str2.length() ? -1 : 1)
				.findFirst()
				.get();
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find length of Longest name
		int lengthofLongestStr = longestStr.length();
		System.out.println("\nLength of Longest String is = " + lengthofLongestStr);
	}
}

Output:

Original String List :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

1.5 Using IntStream.summaryStatistics() method

  • We can get summaryStatistics from the processing Stream elements which has useful methods to get,
    • minimum value
    • maximum value
  • getMax() method of IntSummaryStatistics returns maximum value/element from the processing Stream elements or List or ArrayList
  • Finally, printing length of longest String to the console

FindLongestStringInListUsingJava8IntSummaryStatistics.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.List;

public class FindLongestStringInListUsingJava8IntSummaryStatistics {

	public static void main(String[] args) {

		// 1. names with different length
		List<String> names = Arrays.asList(
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
				);


		// 1.1 print to console
		System.out.println("Original String List :- " + names + "\n");


		// 2. find Longest name and its length in List using .summaryStatistics().getMax()
		int lengthOfLongestStr = names
				.stream()
				.peek(System.out::print)
				.mapToInt(String::length)
				.peek(length -> System.out.println("=" + length))
				.summaryStatistics()
				.getMax();
		System.out.println("\nLength of Longest String is = " + lengthOfLongestStr);
	}
}

Output:

Original String List :- [Bond, Einstein, Alice, Whitman, Bob, Spider]

Bond=4
Einstein=8
Alice=5
Whitman=7
Bob=3
Spider=6

Length of Longest String is = 8

1.6 Using Collection.max() method

  • Collections.max() method accepts 2 input-arguments where
    • 1st argument is the original list
    • 2nd argument is the Comparator, here we are comparing on the basis of String length
  • Collections.max() method returns maximum value/element according to the passed Comparator which here is String length
  • Finally, printing longest String and its length to the console

FindLongestStringInListUsingJava8CollectionMaxMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class FindLongestStringInListUsingJava8CollectionMaxMethod {

	public static void main(String[] args) {

		// 1. names with different length
		List<String> names = Arrays.asList(
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
				);


		// 1.1 print to console=
		System.out.println("Original String List :- \n" + names);


		// 2. find Longest name using Collections.max()
		String longestString = Collections.max(
				names, // List
				Comparator.comparing(String::length) // Comparator
				);
		System.out.println("\nLongest String is = " 
				+ longestString);


		// 2.1 find Length of Longest name
		int lengthOflongestString = longestString.length();
		System.out.println("\nLength of Longest String is = " 
				+ lengthOflongestString);
	}
}

Output:

Original String List :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

2. Finding Longest number in an Arrays:

We will find Longest String in an Arrays using different methods of Java 8 Stream

  • Using Arrays.stream.max() method
  • Using Arrays.stream.collect() method
  • Using Arrays.stream.reduce() method
  • Using Arrays.stream.sorted() method
  • Using IntStream.summaryStatistics() method
  • Using Collection.max() method

2.1 Using Arrays.stream.max() method

  • Arrays.stream.max() method returns maximum value from the processing Stream elements and this method returns Optional<T>
    • get() method of Optional<T> returns longest String from the Arrays
  • Finally, printing longest String and its length to the console

FindLongestStringInAnArraysUsingJava8StreamMaxMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.Comparator;

public class FindLongestStringInAnArraysUsingJava8StreamMaxMethod {

	public static void main(String[] args) {

		// 1. names with different length
		String[] names = new String[] {
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
		};


		// 1.1 print to console
		System.out.println("Original String Arrays :- \n" 
				+ Arrays.toString(names));


		// 2. find Longest name in an Arrays using .max(Comparator.comparingInt(String::length)).get()
		String longestStr = Arrays
				.stream(names)
				.max(Comparator.comparingInt(String::length))
				.get();
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find Length of Longest name in an Arrays using max(Integer::compare).get()
		int lengthOflongestString = Arrays
				.stream(names)
				.map(String::length)
				.max(Integer::compare)
				.get();
		System.out.println("\nLength of Longest String is = " 
				+ lengthOflongestString);
	}
}

Output:

Original String Arrays :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

2.2 Using Arrays.stream.collect() method

  • Pass below arguments to Stream’s collect() method
    • Collectors.maxBy() for finding Longest String from Arrays
    • Collectors.summarizingInt() for finding length of Longest String
  • Collectors.maxBy() accepts Comparator.comparingInt(String::length) as method-argument and returns Optional<T>
    • get() method of Optional<T> returns longest String from Arrays
  • Collectors.summarizingInt() accepts String::length as method-reference and returns IntSummaryStatistics
    • getMax() method of IntSummaryStatistics returns length of longest String from Arrays
  • Finally, printing longest String and its length to the console

FindLongestStringInAnArraysUsingJava8StreamCollectMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.Comparator;
import java.util.stream.Collectors;

public class FindLongestStringInAnArraysUsingJava8StreamCollectMethod {

	public static void main(String[] args) {

		// 1. names with different length
		String[] names = new String[] {
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
		};


		// 1.1 print to console
		System.out.println("Original String Arrays :- \n" 
				+ Arrays.toString(names));


		// 2. find Longest name using collect(Collectors.maxBy(Comparator.comparingInt(String::length)))
		String longestStr = Arrays
				.stream(names)
				.collect(Collectors.maxBy(Comparator.comparingInt(String::length)))
				.get();
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find length of Longest name using collect(Collectors.summarizingInt(String::length))
		int lengthofLongestStr = Arrays
				.stream(names)
				.collect(Collectors.summarizingInt(String::length))
				.getMax();
		System.out.println("\nLength of Longest String is = " + lengthofLongestStr);
	}
}

Output:

Original String Arrays :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

2.3 Using Arrays.stream.reduce() method

  • Arrays.stream.reduce() method accepts IntBinaryOperator to get maximum value from the processing Stream elements by passing lambda-expression as argument
  • In the below illustration we used different lambda-expression to reduce() method,
    • Lambda expression :- (x, y) -> x.length() > y.length() ? x : y for finding Longest String from Arrays
    • Lambda expression :- (x, y) -> Integer.max(x, y) for finding length of Longest String
  • Arrays.stream.reduce() method returns OptionalInt
    • getAsInt() method of OptionalInt returns longest String from Arrays
  • Finally, printing longest String and its length to the console

FindLongestStringInAnArraysUsingJava8StreamReduceMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;

public class FindLongestStringInAnArraysUsingJava8StreamReduceMethod {

	public static void main(String[] args) {

		// 1. names with different length
		String[] names = new String[] {
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
		};


		// 1.1 print to console
		System.out.println("Original String Arrays :- \n" 
				+ Arrays.toString(names));


		// 2. find Longest String using .reduce((x, y) -> x.length() > y.length() ? x : y).get()
		String longestStr = Arrays
				.stream(names)
				.reduce((x, y) -> x.length() > y.length() ? x : y)
				.get();
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find Length of Longest String using .reduce((x, y) -> Integer.max(x, y)).getAsInt();
		int lengthOfLongestStr = Arrays
				.stream(names)
				.mapToInt(String::length)
				.reduce((x, y) -> Integer.max(x, y))
				.getAsInt();
		System.out.println("\nLength of Longest String is = " + lengthOfLongestStr);
	}
}

Output:

Original String Arrays :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

2.4 Using Arrays.stream.sorted() method

  • Arrays.stream.reduce() method sorts String[] Arrays on the basis of String length
  • In the below illustration we are passing lambda-expression to sorted() method to sort according to String length with,
    • higher length String element at the top
    • lower length String element at the bottom
  • findFirst() method returns 1st String which has highest length in the String[] Arrays and it returns Optional<T>
    • get() method of Optional<T> returns longest String from the Arrays
  • Finally, printing longest String and its length to the console

FindLongestStringInAnArraysUsingJava8StreamSortedMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;

public class FindLongestStringInAnArraysUsingJava8StreamSortedMethod {

	public static void main(String[] args) {

		// 1. names with different length
		String[] names = new String[] {
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
		};


		// 1.1 print to console
		System.out.println("Original String[] Arrays :- \n" 
				+ Arrays.toString(names));


		// 2. find Longest name using .sorted((str1, str2) -> str1.length() > str2.length() ? -1 : 1)
		String longestStr = Arrays
				.stream(names)
				.sorted((str1, str2) -> str1.length() > str2.length() ? -1 : 1)
				.findFirst()
				.get();
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find length of Longest name
		int lengthofLongestStr = longestStr.length();
		System.out.println("\nLength of Longest String is = " + lengthofLongestStr);
	}
}

Output:

Original String[] Arrays :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

2.5 Using IntStream.summaryStatistics() method

  • We can get summaryStatistics from the processing Stream elements which has useful methods to get,
    • minimum value
    • maximum value
  • getMax() method of IntSummaryStatistics returns maximum value/element from the processing Stream elements or Arrays
  • Finally, printing length of longest String to the console

FindLongestStringInAnArraysUsingJava8IntSummaryStatistics.java

package in.bench.resources.longest.string;

import java.util.Arrays;

public class FindLongestStringInAnArraysUsingJava8IntSummaryStatistics {

	public static void main(String[] args) {

		// 1. names with different length
		String[] names = new String[] {
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
		};


		// 1.1 print to console
		System.out.println("Original String Arrays :- \n" 
				+ Arrays.toString(names) + "\n");


		// 2. find Longest name and its length in List using .summaryStatistics().getMax()
		int lengthOfLongestStr = Arrays
				.stream(names)
				.peek(System.out::print)
				.mapToInt(String::length)
				.peek(length -> System.out.println("=" + length))
				.summaryStatistics()
				.getMax();
		System.out.println("\nLength of Longest String is = " + lengthOfLongestStr);
	}
}

Output:

Original String Arrays :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Bond=4
Einstein=8
Alice=5
Whitman=7
Bob=3
Spider=6

Length of Longest String is = 8

2.6 Using Collection.max() method

  • Collections.max() method accepts 2 input-arguments where,
    • 1st argument is the list (convert original Arrays into List using Arrays.asList(); method)
    • 2nd argument is the Comparator, here we are comparing on the basis of String length
  • Collections.max() method returns maximum value/element according to the passed Comparator which here is String length
  • Finally, printing longest String and its length to the console

FindLongestStringInAnArraysUsingJava8CollectionMaxMethod.java

package in.bench.resources.longest.string;

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;

public class FindLongestStringInAnArraysUsingJava8CollectionMaxMethod {

	public static void main(String[] args) {

		// 1. names with different length
		String[] names = new String[] {
				"Bond",
				"Einstein",
				"Alice",
				"Whitman",
				"Bob",
				"Spider"
		};


		// 1.1 print to console
		System.out.println("Original String[] Arrays :- \n" 
				+ Arrays.toString(names));


		// 2. find Longest name in an Arrays using Collections.max()
		String longestStr = Collections.max(
				Arrays.asList(names), // Arrays converted to List
				Comparator.comparing(String::length) // Comparator
				);
		System.out.println("\nLongest String is = " + longestStr);


		// 2.1 find Length of Longest name
		int lengthOflongestString = longestStr.length();
		System.out.println("\nLength of Longest String is = " 
				+ lengthOflongestString);
	}
}

Output:

Original String[] Arrays :- 
[Bond, Einstein, Alice, Whitman, Bob, Spider]

Longest String is = Einstein

Length of Longest String is = 8

Related Articles:

References:

Happy Coding !!
Happy Learning !!

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