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up vote 0 down vote favorite

I have the following code and i get Null pointer exception at this line: unWanted[g].equals("")

I dont know how can it be because i check before that if unWanted isnt null. Thank for helping :)

public String[] setExercies(){

DataBaseMain data = new DataBaseMain(this);
data.open();
String[] unWanted = data.getAllUnwantedExercies();  
String[] exits = data.getAllExercies();
data.close();

if(unWanted == null)
    return exits;

int f = 0;

for(int g = 0; g < unWanted.length; g++)
{
    if(unWanted[g].equals(""))
        f++;
}

String[] temp = new String[unWanted.length-f];
f = 0;

for (int k = 0; k < unWanted.length; k++){
    if(unWanted[k].equals("") == false)
    {
        temp[f] = unWanted[k];
        f++;
    }
}
share|improve this question
2  
Looks like unWanted[g] is null at some value of g. Do a null check before applying the equals. – Luiggi Mendoza May 10 '13 at 16:34
    
have you checked if this function (data.getAllUnwantedExercies();) is returning values and not null? – SKK May 10 '13 at 16:39
2  
when compairing a string to a constant, invert the test such that the constant .equals the non constant. for example, in stead of blam.equals("hoot") which will throw an NPE if blam is null, use "hoot".equals(blam) which wil lnever throw an NPE. – DwB May 10 '13 at 16:45
    
@DwB: on the other hand, detecting the NPE early is often a good thing, because having a null element in the array is probably a bug that needs to be fixed. – JB Nizet May 10 '13 at 16:57

3 Answers 3

up vote 0 down vote accepted

for some reason your getAllUnwantedExercies() is returning null.

u can check null in here

for(int g = 0; g < unWanted.length; g++)
{
    if(unwanted[g] != null && unWanted[g].equals(""))
        f++;
}
share|improve this answer
    
thanks :) its working. – tomer May 10 '13 at 16:50
up vote 0 down vote

The string value inside unWanted is null. You'll need an additional null check. Use one of these depending on your intent

for(int g = 0; g < unWanted.length; g++)
{
    if(unWanted[g] == null || unWanted[g].equals(""))
        f++;
}

for(int g = 0; g < unWanted.length; g++)
{
    if(unWanted[g] != null && unWanted[g].equals(""))
        f++;
}
share|improve this answer
up vote 0 down vote

One of the values in your array unWanted is null. You'll have to find out which index contains it but you could try:

for(int g = 0; g < unWanted.length; g++)
{
  String unWantedVal = unWanted[g];
  if(unWantedVal == null)
     System.out.println("Index " + g + " has a null value!");
  else if(unWantedVal.equals(""))
        f++;
}
share|improve this answer

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