Question

How to initialize a list in one line with Java

Answer 1

import java.util.List;
import java.util.Arrays;
import java.util.ArrayList;
 
public class InitList {
 
    static void printList(List<Character> list) {
        for (char ch : list) {
            System.out.print(ch + " ");
        }
        System.out.println();
    }
 
 
    public static void main(String[] args) {
        List<Character> list1 = new ArrayList<>(Arrays.asList('a', 'b', 'c'));
        List<Character> list2 = List.of('a', 'b', 'c');
        List<Character> list3 = Arrays.asList('a', 'b', 'c');
 
        System.out.println(list1);
        System.out.println(list2);
        System.out.println(list3);
         
        printList(list1);
        printList(list2);
        printList(list3);
    }
}
 
 
 
/*
run:
 
[a, b, c]
[a, b, c]
[a, b, c]
a b c 
a b c 
a b c 
 
*/

 

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Answer 2

import java.util.List;
import java.util.Arrays;
import java.util.ArrayList;
 
public class InitList {
 
    static void printList(List<String> list) {
        for (String s : list) {
            System.out.print(s + " ");
        }
        System.out.println();
    }
 
 
    public static void main(String[] args) {
        List<String> list1 = Arrays.asList(new String[]{"java", "c", "c++"});
        List<String> list2 = List.of("java", "c", "c++");
        List<String> list3 = Arrays.asList("java", "c", "c++");
 
        System.out.println(list1);
        System.out.println(list2);
        System.out.println(list3);
         
        printList(list1);
        printList(list2);
        printList(list3);
    }
}
 
 
 
/*
run:
 
[java, c, c++]
[java, c, c++]
[java, c, c++]
java c c++ 
java c c++ 
java c c++ 
 
*/

 

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Answer 3

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

public class InitList {

    static void printList(List<Long> list) {
        for (Long l : list) {
            System.out.print(l + " ");
        }
        System.out.println();
    }


    public static void main(String[] args) {
        List<Long> list1 = new ArrayList<Long>(Arrays.asList(1L, 2L, 3L));
        List<Long> list2 = List.of(1L, 2L, 3L);
        List<Long> list3 = Arrays.asList(1L, 2L, 3L);

        System.out.println(list1);
        System.out.println(list2);
        System.out.println(list3);
        
        printList(list1);
        printList(list2);
        printList(list3);
    }
}


/*
run:

[1, 2, 3]
[1, 2, 3]
[1, 2, 3]
1 2 3 
1 2 3 
1 2 3 

*/

 

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Answer 4

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

public class InitList {

    // Print a list of characters
    static void printList(List<Integer> list) {
        for (Integer i : list) {
            System.out.print(i + " ");
        }
        System.out.println();
    }


    public static void main(String[] args) {
        List<Integer> list1 = new ArrayList<Integer>(Arrays.asList(1, 2, 3));
        List<Integer> list2 = List.of(1, 2, 3);
        List<Integer> list3 = Arrays.asList(1, 2, 3);

        System.out.println(list1);
        System.out.println(list2);
        System.out.println(list3);
        
        printList(list1);
        printList(list2);
        printList(list3);
    }
}


/*
run:

[1, 2, 3]
[1, 2, 3]
[1, 2, 3]
1 2 3 
1 2 3 
1 2 3 

*/

 

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