void update() { String balString = balField.getText(); String intString = intField.getText(); String nyrString = nyrField.getText(); if (balString.trim().length() == 0) msgArea.setText("Principal amount missing"); else if (intString.trim().length() == 0) msgArea.setText("Interest rate missing"); else if (nyrString.trim().length() == 0) msgArea.setText("Number of years missing"); else { double bal = new Double(balString).doubleValue(); double intyr = new Double(intString).doubleValue() / 100.; short nyears = (short) new Integer(nyrString).intValue();