[Java] Sort the list using streams and lambda expressions

Sort the list using streams and lambda expressions

By using streams and lambda expressions, you can reduce the coding of list sorting.

Code example

Main.java


package sample;
import java.util.List;
import java.util.stream.Collectors;

public class Main {
	public static void main(String[] args) {
		//List setting (method without add method)
		List<String> sampleList = List.of("Ishikari","Sorachi","Shiribeshi","Iburi","Hidaka","Hiyama","Oshima","Rumoi","Kamikawa","Soya","Tokachi","Kushiro","Okhotsk","Nemuro");

		//Check the created list samples

		System.out.println(sampleList);
		System.out.println("");

		//Sort the created list samples using streams and lambda expressions
		// A → Z
		List<String> sortedSampleList1 = sampleList.stream().sorted((a,b) -> (a.compareTo(b))).collect(Collectors.toList());
		System.out.println("A → Z");
		System.out.println(sortedSampleList1);
		System.out.println("");

		// Z → A
		System.out.println("Z → A");
		List<String> sortedSampleList2 = sampleList.stream().sorted((a,b) -> (b.compareTo(a))).collect(Collectors.toList());
		System.out.println(sortedSampleList2);
	}
}

Output result

[Ishikari, Sorachi, Shiribeshi, Iburi, Hidaka, Hiyama, Oshima, Rumoi, Kamikawa, Soya, Tokachi, Kushiro, Okhotsk, Nemuro]

A → Z
[Hidaka, Hiyama, Iburi, Ishikari, Kamikawa, Kushiro, Nemuro, Okhotsk, Oshima, Rumoi, Shiribeshi, Sorachi, Soya, Tokachi]

Z → A
[Tokachi, Soya, Sorachi, Shiribeshi, Rumoi, Oshima, Okhotsk, Nemuro, Kushiro, Kamikawa, Ishikari, Iburi, Hiyama, Hidaka]

Remarks

In programming (Java) of the Fundamental Information Technology Engineer Examination, code using stream lambda expressions is sometimes given as a subject.

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