//计算3个整数的乘积
import javax.swing.JOptionPane;
public class mul3{  
  public void main(String args[])
  { String firstNumber;
    String secondNumber;
    String thirdNumber;
   
   int number1;
   int number2;
   int number3;
   int result;
   
   firstNumber = JOptionPane.showInputDialog("输入第一个整数");
   secondNumber = JOptionPane.showInputDialog("输入第二个整数");
   thirdNumber = JOptionPane.showInputDialog("输入第三个整数");
   
   number1 = Integer.parseInt(firstNumber);
   number2 = Integer.parseInt(secondNumber);
   number3 = Integer.parseInt(thirdNumber);
   
   result = number1*number2*number3;
   
   JOptionPane.showMessgeDialog(null,"结果是" + result,"求3个整数的乘积",
                                JOptionPane.PLAIN_MESSAGE);
  }
} //编译倒数第3行出错

方法拼写错误，以后自己看仔细了再问！

颇有些俺的风格——粗心！呵呵……

呵呵 是啊 偶也有点粗心啊~不过我用jc来编写然后用记事本和cmd来编译

最好在main函数后加个throws Exception,最后一行的JOptionPane.showMessgeDialog改为JOptionPane.showMessageDialog就行了!