讓我得到這個錯誤:java的 '無效' 類型不在這裏
--------------------Configuration: <Default>--------------------
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());
^
從這個代碼:
// 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;
}
}
什麼問題?