title: java 'void' type not allowed here
body: <p>I get this error:</p>
  
  <pre><code>--------------------Configuration: &lt;Default&gt;--------------------
  C:\Documents and Settings\800508\Desktop\Chpt 8\Labs08\Lab08MATH02\Lab08MATH02st.java:20: 'void' type not allowed here
      JOptionPane.showMessageDialog(null,r.getRational() + " equals " + r.getDec() + " and reduces to " + r.reduce());
                                                                                   ^
  </code></pre>
  
  <p>From this code:</p>
  
  <pre><code>// Lab08MATH02st.java
  // The Rational Class Program I
  // This is the student, starting version of the Lab08MATH02 assignment.
  
  
  import javax.swing.JOptionPane;
  
  
  public class Lab08MATH02st
  {
      public static void main (String args[])
      {   
      String strNbr1 = JOptionPane.showInputDialog("Enter Numerator 1");
      String strNbr2 = JOptionPane.showInputDialog("Enter Denominator 2");
  
      int num = Integer.parseInt(strNbr1);
      int den = Integer.parseInt(strNbr2);
  
      Rational r = new Rational(num,den);
      JOptionPane.showMessageDialog(null,r.getRational() + " equals " + r.getDec() + " and reduces to " + r.reduce());
  
      System.exit(0); 
      }
  }
  
  
  
  class Rational
  {
  
  int num;
  int den;
  int n1;
  int n2;
  int gcf; 
  
  public Rational(int n, int d)
  {
  num = n;
  den = d;
  }
  
  
  //  Rational
  
  //  getNum
  
  //  getDen
  
  //  getDecimal
      public double getDec()
      {
          return (double)num/den;
      } 
  //  getRational 
      public String getRational()
      {
          return num + "/" + den;
      } 
  //  getOriginal
  
  //  reduce
      public void reduce()
      {
      num = num / 2;
      den = den / 2;
      }
  
  
  
      private int getGCF(int n1,int n2)
      {
          int rem = 0;
          int gcf = 0;
          do
          {
              rem = n1 % n2;
              if (rem == 0)
                  gcf = n2;
              else
              {
                  n1 = n2;
                  n2 = rem;
              }
          }
          while (rem != 0);
          return gcf;
          } 
  }
  </code></pre>
  
  <p>What's the problem?</p>