Question

When I try to output the strings from the modules

public class Module
{
public String moduleName;
 //public String moduleResults;

 public void setModuleName(String aModuleName)
 {
    moduleName = aModuleName;
 }
 public String getModuleName()
 {
    return moduleName;   
 }
}

using

public void displayModules()
 {
    for (int i = 0; i < moduleArray.length; i++)
    {
        System.out.println(moduleArray[i].getModuleName());  
    }        
 }

I get a NPE when the array(of length 4) is not full and when it is full nothing is outputted when I use the method. I’m using blueJ if that makes a difference.

Answer 1

Your NPE comes from trying to call getModuleName on a null reference.

System.out.println((moduleArray[i]!=null)?moduleArray[i].getModuleName():"null");  

As to why nothing gets printed when you do have valid elements, I suppose you might not be setting the names correctly, elsewhere.