How many times have you used the statement: JOptionPane.showMessageDialog? If your answer is more than once go back and revise your code so that you only use ONE JOptionPane.showMessageDialog
Hint: consider using a variable of type String named output
Code
if(credit >= 120)
{
JOptionPane.showMessageDialog(null,"You've graduated!");
}//end if
else if(credit >= 90)
{
JOptionPane.showMessageDialog(null,"You're a senior.");
}//end if
else if(credit >= 60)
{
JOptionPane.showMessageDialog(null,"You're a junior.");
}//end if
else if(credit >= 30)
{
JOptionPane.showMessageDialog(null,"You're a sophomore.");
}//end if
else if(credit >=0)
{
JOptionPane.showMessageDialog(null,"You're a freshment.");
}//end if
else
{
JOptionPane.showMessageDialog(null,"invalid input");
Use the if-else statements to generate the String to show, then use a single line to call showMessageDialog() using the String.