Question

I use Eclipse to write the code and I get a red underline at customHandler.saveTransactionToFile(); and it says

Unhandled exeption type IOException.

Why does this happen and how could I solve it?

// Call method in customHandler class to write to file when button is pressed
public void actionPerformed(ActionEvent event)
{
    // Save transactions to file
    if(event.getSource()== buttonSaveTransaction)
    {
         customHandler.saveTransactionToFile();
    }
}

// Method in class customHandler that writes to file
public void saveTransactionToFile() throws IOException
{
    System.out.println("Skriver till fil");
    File outFile = new File("C:/JavaBank/" + selectedCustomerAccountNumber + ".data");
    FileOutputStream outFileStream = new FileOutputStream(outFile);
    PrintWriter outStream = new PrintWriter(outFileStream);
    outStream.println("test");
    outStream.close();  
}

Answer 1

Inside your actionPerformed() method ,, write

customHandler.saveTransactionToFile();

write this like

public void actionPerformed(ActionEvent event)
{
    // Save transactions to file
    if(event.getSource()== buttonSaveTransaction)
    {
        try
        {
            customHandler.saveTransactionToFile();
        }
        catch(IOException ioe)
        {
            ioe.printStackTrace();
        }
   }
}

To answer as to why you have to do this “It’s because the method being called for i.e. customHandler.saveTransactionToFile();, is known to throw IOException as mentioned by you in the definition.”

Hope that will help

Regards