I'm a new programmer and every time I run this block of code I get a null pointer exception in Java

Question

//This Is the Class
private String words;
private File textFile;
private Scanner inputFile;
StringBuilder stringBuilder = new StringBuilder();
public Scramble(String j) throws FileNotFoundException
{
File textFile = new File(j);

Scanner inputFile = new Scanner(textFile);
}

public String getRealWord() throws IOException                                    
{
//Make the loop while !null
//if null close the document
while (inputFile.hasNext())
    {

    stringBuilder.append(inputFile);

    }
    inputFile.close();



return stringBuilder.toString();
}

This is the call to the class in the main method String word = theScramble.getRealWord(); What portion should I change to avoid the null pointer exception

Answer 1

You're re-declaring your variables in the local scope. Within your Scramble constructor:

File textFile = new File(j);

...is declaring a new variable called textFile , which hides the instance member also called textFile .

You'll want to change:

public Scramble(String j) throws FileNotFoundException
{
   File textFile = new File(j);
   Scanner inputFile = new Scanner(textFile);
}

To:

public Scramble(String j) throws FileNotFoundException
{
   textFile = new File(j);
   inputFile = new Scanner(textFile);
}

This way, you're referring to the instance variables, not the local variables.