public/subjects/java-piscine/ListSearchIndex

ListSearchIndex

Instructions

Create a file ListSearchIndex.java.

Write a function findLastIndex that returns the last index of an element in a list. Returns null otherwise.
Write a function findFirstIndex that returns the first index of an element in a list. Returns null otherwise.
Write a function findAllIndexes that returns a list of all indexes of an element in a list. Returns an empty list otherwise.

Expected Functions

import java.util.List;

public class ListSearchIndex {
    public static Integer findLastIndex(List<Integer> list, Integer value) {
        // your code here
    }
    public static Integer findFirstIndex(List<Integer> list, Integer value) {
        // your code here
    }
    public static List<Integer> findAllIndexes(List<Integer> list, Integer value) {
        // your code here
    }
}

Usage

Here is a possible ExerciseRunner.java to test your function :

import java.util.List;

public class ExerciseRunner {
    public static void main(String[] args) {
        System.out.println(ListSearchIndex.findLastIndex(List.of(9, 13, 89, 8, 23, 1, 0, 89), 89));
        System.out.println(ListSearchIndex.findFirstIndex(List.of(9, 13, 89, 8, 23, 1, 0, 89), 89));
        System.out.println(ListSearchIndex.findAllIndexes(List.of(9, 13, 89, 8, 23, 1, 0, 89), 89).toString());
    }
}

and its output :

$ javac *.java -d build
$ java -cp build ExerciseRunner 
7
2
[2, 7]
$ 

Notions

List
ArrayList