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 https://stackoverflow.com/questions/13102045/scanner-is-skipping-nextline-after-using-next-or-nextfoo Add a `input.nextLine()` after your `input.nextInt()` — RaffleBuffle, Oct 08 '18 at 02:04
Possible duplicate of [Scanner is skipping nextLine() after using next() or nextFoo()?](https://stackoverflow.com/questions/13102045/scanner-is-skipping-nextline-after-using-next-or-nextfoo) — GBlodgett, Oct 08 '18 at 02:34

score 1 · Accepted Answer · answered Oct 08 '18 at 02:40

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.

score 0 · Answer 2 · answered Oct 08 '18 at 02:22

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();
        }
    }

Java Array 2D not working with parameters

2 Answers2