Java Array 2D not working with parameters

Question

I'm new in the community and I need help with Array 2d in Java Is a project for school this is my problem

I build Array 2D with static length and work but the same code with parameters not work.

First print the System.out.print("Insert Name");

after that not execute the statement matrix[i][0] = input.nextLine();

third print System.out.print("Insert Last Name");

now works but the index [0],[0] is empty

Example of print:

a

b b

c c

Thanks!!!

import java.util.*;

public class Students {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner input = new Scanner(System.in);

    System.out.println("Insert number of Students");

    int numStudents = input.nextInt();

    String[][] matrix = new String[numStudents][2];

    for (int i = 0; i < numStudents; i++) {

        System.out.print("Insert Name");

        matrix[i][0] = input.nextLine();                                                                            

        for (int j = 1; j < 2; j++) {

            System.out.print("Insert Last Name");

            matrix[i][j] = input.nextLine();

        }
    }

    for(int z=0; z<numStudents ;z++) {

        System.out.println();

        for(int h=0; h<2;h++) {

            System.out.printf(matrix[z][h]);
            System.out.printf(" ");
        }

    }

   }
  }

Duplicate of stackoverflow.com/questions/13102045/… Add a input.nextLine() after your input.nextInt() — RaffleBuffle
– RaffleBuffle, Commented Oct 8, 2018 at 2:04
Possible duplicate of Scanner is skipping nextLine() after using next() or nextFoo()? — GBlodgett
– GBlodgett, Commented Oct 8, 2018 at 2:34

Parivesh Chamoli · Accepted Answer · 2018-10-08 02:40:13Z

1

Use String value= input.next(); instead of input.nextLine(); or use an extra input.nextLine(); after input.nextInt(); i.e.

int numStudents = input.nextInt();
input.nextLine()

This happens because input.nextInt() just reads one integer and does not finishes the line.

answered Oct 8, 2018 at 2:40

Parivesh Chamoli

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Comments

Amit Phaltankar · Accepted Answer · 2018-10-08 02:22:51Z

I think this should work for you. No need of a nested for loop to read last name.

   public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);

        System.out.println("Insert number of Students");

        int numStudents = input.nextInt();
        input.nextLine();
        String[][] matrix = new String[numStudents][2];

        for (int i = 0; i < numStudents; i++) {

            System.out.println("Insert Name");
            matrix[i][0] = input.nextLine();
            System.out.println("Insert Last Name");
            matrix[i][1] = input.nextLine();
        }

        for (int z = 0; z < numStudents; z++) {
            System.out.println();
            for (int h = 0; h < 2; h++) {
                System.out.print(matrix[z][h]);
                System.out.print(" ");
            }
            System.out.println();
        }
    }

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