Passing an array into another method in java

Question

I have a class called Player that defines the characteristics of a Player. I have a method called readPlayer in another class:

void readPlayer(String playerInfo) {
    int j = 0;
    int playerNumber = 0;
    int playerCount = 0;
    String splitPipe = "\\|"; // split by pipe
    String splitColon = "\\:"; // split by colon
    String splitInput[] = playerInfo.split(splitPipe + "|" + splitColon);
    for (int i = 0; i < splitInput.length; i += 5) {
        playerCount++; // keeps track of how many players there are
    }
    players = new Player[playerCount];// initializes array to amount of players
    while (playerNumber < playerCount) {
        players[playerNumber] = new Player(Integer.parseInt(splitInput[j]), splitInput[j + 1], splitInput[j + 2],
                splitInput[j + 3], splitInput[j + 4]);
        j += 5;
        playerNumber++;
    }
    pR.printPlayers(players); //ERROR: NullPointerException thrown here
}

But when I try to pass the players array to printPlayers in another class it gives me and NullPointerException error

Details of error:

Exception in thread "main" java.lang.NullPointerException
    at ca.bcit.comp2613.PlayerReader.readPlayer(PlayerReader.java:30)
    at ca.bcit.comp2613.Lab2.main(Lab2.java:16)

This is my main method:

static PlayerReader p = new PlayerReader(); 
public static void main(String[] args) {
    if(args.length == 0) { 
        System.out.println("Usage java -jar project.jar <input String>");
        System.exit(-1);
    } else { 
        p.readPlayer(args[0]);
    }
}
}

This is my printPlayer method - Nothing special not doing anything with it right now

public class PlayerReport {

    public void printPlayers(Player players[]) {

    }
}

You should show printPlayers method as exception is being thrown there. — Ouney, May 28 '15 at 04:38
That's a `NullPointerException` you got right there, not an `ArrayIndexOutOfBoundsException`. — Robby Cornelissen, May 28 '15 at 04:41
where did you initialized `pR` ? give the full code of class which contain `void readPlayer(String playerInfo)` — Saif, May 28 '15 at 04:51
Since you have initialized the array `Players`, the only option is that the variable `pR` is `null`. So not related at all to "passing an array to another method" as mentioned in the title. — Erwin Bolwidt, May 28 '15 at 05:05
I have tried running the code with adding instance of PlayerReport and changing Player constructor to "no arguments constructor". It works all right, throwing no exception. The problem may be with pR. — RehanZahoor, May 28 '15 at 05:10
PlayerReport pR = new PlayerReport(); if the constructor is parameterized constructor, provide the parameters — Mideesh Punathil, May 28 '15 at 05:12
NPE at line `pR.printPlayers(players);` implies `pR` is not initialized. — Naman Gala, May 28 '15 at 05:13

score 0 · Answer 1 · edited May 28 '15 at 06:03

    public class Player {
    public Player(int parseInt, String string, String string2, String string3,
            String string4) {
        // Do initialization
    }

    public static void main(String args[]) {
        // if(args.length == 0) {
        // System.out.println("Usage java -jar project.jar <input String>");
        // System.exit(-1);
        // } else {
        // p.readPlayer(args[0]);
        // }
        PlayerReader p = new PlayerReader();
        p.readPlayer("playerInfo");
    }
}

class PlayerReport {

    public void printPlayers(Player players[]) {
        System.out.println("Printing....");
    }
}

class PlayerReader {

    void readPlayer(String playerInfo) {
        int j = 0;
        int playerNumber = 0;
        int playerCount = 0;
        String splitPipe = "\\|"; // split by pipe
        String splitColon = "\\:"; // split by colon
        String splitInput[] = playerInfo.split(splitPipe + "|" + splitColon);
        for (int i = 0; i < splitInput.length; i += 5) {
            playerCount++; // keeps track of how many players there are
        }
        Player[] players = new Player[playerCount];// initializes array to
                                                    // amount of players
        while (playerNumber < playerCount) {
            // players[playerNumber] = new
            // Player(Integer.parseInt(splitInput[j]),
            // splitInput[j + 1], splitInput[j + 2], splitInput[j + 3],
            // splitInput[j + 4]);
            players[playerNumber] = new Player(1, "3", "4", "5", "6");

            j += 5;
            playerNumber++;
        }
        PlayerReport pR = new PlayerReport();
        pR.printPlayers(players); // ERROR: NullPointerException thrown here
    }
}

score 0 · Answer 2 · answered May 28 '15 at 06:56

0

As alluded to in another answer, you haven't shown how you have instantiated either of the "pR" or "players" objects.

Not sure what the "pR" object is but that is what is causing your Null Pointer.

answered May 28 '15 at 06:56

Scott Bennett-McLeish

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Passing an array into another method in java

2 Answers2