//Adder.java
class Adder  {
  private int operand1;
  private int operand2;
  private int addResult;
  private int minusResult;
  private int mulResult ;
  private float divResult;
  private String errMessage;

  public Adder() {
     operand1 = 0 ;
     operand2 = 0;
  }
  public void setOperand1(int pNumber) {
     operand1 = pNumber;
  }
  public void setOperand2(int pNumber) {
     operand2 = pNumber;
  }
  private void realCalculate(int pData1, int pData2) {
     addResult   = pData1 + pData2;
     minusResult = pData1 - pData2;
     mulResult   = pData1 * pData2;

     divResult = -1;
     if (pData2 !=0) {
        divResult = pData1 / (float)pData2;
        }
  }
  public void calculate() {
     realCalculate(operand1 , operand2) ;
  }
  public void reverseCalculate() {
     realCalculate(operand2 , operand1);
  }
  public int getAddResult()   { return addResult ;}
  public int getMinusResult() { return minusResult;}
  public int getMulResult()   { return mulResult;}
  public float getDivResult() { return divResult;}
}

//ex2Prog.java
class ex2Form {
   private Adder adder1 ;
   private int data1;
   private int data2;
   public ex2Form() {
      adder1 = new Adder();
      data1  = 12;
      data2  = 4;
   }
   private void displayResult()  {
      System.out.println("["  + data1 + "] : [" + data2 + "]");
      System.out.println("+[" + adder1.getAddResult()   + "]");
      System.out.println("-[" + adder1.getMinusResult() + "]");
      System.out.println("*[" + adder1.getMulResult()   + " ");
      System.out.println("%[" + adder1.getDivResult()   + "]");
   }
   public void progRun() {

   adder1.setOperand1(data1);
   adder1.setOperand2(data2);

   adder1.calculate() ; displayResult() ;
   adder1.reverseCalculate() ; displayResult();

   data2 = 5; adder1.setOperand2(data2);

   adder1.calculate() ; displayResult();
   adder1.reverseCalculate() ; displayResult();
   }
}

public class ex2Prog {
   public static void main(String[] arg) {
      ex2Form e1;

      e1 = new ex2Form();
      e1.progRun();
   }
}