problem searching for a String element in a parallel array

**david185000** · July 27th, 2010, 11:03 AM

Hi guys

I have a parallel array of 5 team names and 5 scores

The user enters a team to search for and it is stored in the variable team

this is my code

String team;
int loopcount;
 
System.out.println("Please enter the team you would like to search for: ");
team = input.next(); // identify team to be searched for
 
 
for(loopcount = 0; loopcount < 5; loopcount++)
{
     if (teaminfo[0][loopcount].equals(team) ) { 
          System.out.println("Search has found : " + teaminfo[0][loopcount] + " at position: " + (loopcount+1));
     } 
}

However when for some reason the for loop does not seem to be functioning. Have a made a glaring obvious newbie error?

**Freaky Chris** · July 27th, 2010, 11:12 AM

Firstly, Welcome to Java Programming Forums I hope you find all the help you need here and more!

Been a while since I actually practiced Java lol, But i cannot see any flaws in what you have done, perhaps it's to do with the declaration & initiation of the variable 'teaminfo'

Of course you should be aware that input.next() will read only the next word input for example, if the input was "liverpool fc" only "liverpool" would be read. This might be the problem? In which case I suggest nextLine()

Please use [hightlight=java]// You Code here[/highlight] tags when posting Java code.

Thanks,
Chris

**copeg** · July 27th, 2010, 11:13 AM

Originally Posted by david185000

However when for some reason the for loop does not seem to be functioning.

What do you mean not functioning? Does it compile? What behavior do you expect to get? How is your array structured? More info the better.

**david185000** · July 27th, 2010, 11:24 AM

Hi guys thanks for your replies and the welcome!
Ive included my code for the entire program in case there are any obvious flaws, but I really am perplexed at why this loop isnt working. Ill press run, and the program will run so i enter my teams and there score. I get to enter team to search for and that is input but then nothing except this error message in the console window

Exception in thread "main" java.lang.NullPointerException
at teams.searchteam(teams.java:82)
at teams.main(teams.java:94)

//
 
import java.util.*;
/*
 * Filename: teams.java
 * created by: David Pepper
 * Created on: 27 Jul 2010
 * Updated on: 27 Jul 2010
 * comment:
 */
 
public class teams
{
	private static Scanner input = new Scanner(System.in);
	static String teaminfo[][] = new String[5][5];
 
 
 
 
	public static String team4()
{
		String value4;
		String ireland = new String ("ireland");
 
		System.out.println("enter ireland as the fourth team: ");
		value4 = input.next();
 
		if(value4.equals(ireland))
		{
			return null;
		}
 
		else 
		{
		System.out.println("you did not enter ireland as team4, please do this now:");
		team4();
		}
 
		return null;				
 
 
	}
 
	public static void addteaminfo()
{
		String teaminfo[][] = new String[5][5];
 
		for (int i = 0; i < teaminfo.length; i++)    // enter team names ensuring that ireland is team 4
		{
			if (i != 3){
			System.out.println("Please enter team "+ (i+1) + ":");
			teaminfo[0][i]= input.next();
			}
			else team4();
			teaminfo[0][3] = "ireland";
		}
 
 
		for (int i = 0; i < teaminfo.length; i++)     // enter team scores
		{
			System.out.println("Please enter " +  teaminfo[0][i] + "'s score");
			teaminfo[1][i]= input.next();
		}	
 
 
 
}
 
	public static  void searchteam()
{
			String team;
			int loopcount;
 
			System.out.println("Please enter the team you would like to search for: ");
			team = input.next();            // identify team to be searched for
 
 
 
 
 
			for(loopcount = 0; loopcount < 5; loopcount++)
			{
 
				if (teaminfo[0][loopcount].equals(team) )  // If search comes across desired value print out location
				{ 
					System.out.println("Search has found : " + teaminfo[0][loopcount] + " at position: " + (loopcount+1));
				}	
 
			}
 
}
 
	public static void main(String[] args)
	{
		addteaminfo();
		searchteam();
	}
 
 
}

**copeg** · July 27th, 2010, 12:05 PM

The error should point you to the exact line of code where the problem is. Here's the train of thought: something is null, go to line 82 and behold there is the variable teamInfo. Looking around, there is no code which actually creates the value of the teamInfo (look closely at the addTeamInfo function and the scope of the variables you assign).

**Freaky Chris** · July 27th, 2010, 12:08 PM

Thanks to scoping laws you killed yourself lol. You declared teaminfo as a global variable, correct. But then when you assign all the teams to it you have declared it as a local variable. So the local version masks the global variable. So when the end of addteaminfo is reach the local one goes out of scope with all the data and then when you call searchteam() you are checking the team against a variable which hasn't had values assignment to it, thus giving you a null pointer exception

Chris

**david185000** · July 27th, 2010, 12:10 PM

Originally Posted by copeg

The error should point you to the exact line of code where the problem is. Here's the train of thought: something is null, go to line 82 and behold there is the variable teamInfo. Looking around, there is no code which actually creates the value of the teamInfo (look closely at the addTeamInfo function and the scope of the variables you assign).

I see. So Ive assigned information to the array in addTeamInfo()

How do I make that information accessible from the main method?

Im sure this is easy enough. However Im using java for the first time in 5 years for a project to get back into uni and there are a few basics that are eluding me

**Freaky Chris** · July 27th, 2010, 12:14 PM

The clue to the solution is in the Scoping laws & masking. It's an easy fix.

Chris

**david185000** · July 27th, 2010, 12:27 PM

Originally Posted by Freaky Chris

The clue to the solution is in the Scoping laws & masking. It's an easy fix.

Chris

Im afraid I dont have a clue what that means

**Freaky Chris** · July 27th, 2010, 12:34 PM

If you wish to return to Uni with a working knowledge of Java then you need to find Google

Here is a simplified version of what you are doing.

public class Example {
     private int myInt;
     public static void main(String[] args){
          myInt = 5;
          System.out.println(myInt);
          changeMyInt();
          System.out.println(myInt);
          changeMyInt2();
          System.out.println(myInt);
     }
     private static void changeMyInt(){
          int myInt = 22;
     }
     private static void changeMyInt2(){
         myInt = 33;
     }
}

Chris

**Norm** · July 27th, 2010, 01:24 PM

Cross posted at problem searching for a String element in a paralell array - Java Forums

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