Question

I have an application which requires to check if a String is present in an array of String type, before adding it so as to avoid duplication. To do this, I wrote the following function:

public boolean arrayHas(String[] arr, String str)
{
    for(int i=0;i<arr.length;i++)
    {
        if(arr[i].equals(str))
            return true;
    }
    return false;
}

To invoke this function, I’m using:

if(!arrayHas(contacts,str))
{
    contacts[i] = str;
    i++;
}

contacts and str are declared as follows

public static  String contacts[] = new String[]{};
String str = "";
Bundle bun = getIntent().getExtras();
str = bun.getString("key");

Elements are added to ‘contacts’ only through the main code, it is empty at the beginning. I tried adding a toast to display the value of ‘str’ received through the intent and it works fine. But I’m getting a NullPointerException in the ‘if’ statement in the arrayHas function. Could someone help me out?

Answer 1

Seems that you haven’t initialized the array with elements. So all of them are NULL.

In you arrayHas function check if the element you are comparing with is a null or not.

if(arr[i] != null && arr[i].equals(str) )
{
    // do your operation
}

Also before calling arrayHas function in

if(arrayHas(contacts,str)) { }

put a check if contacts is null or not.