Object Calling need to clarify

Question

Dear Experts,I need a little help.Please read the following code to give me some answers:
<pre>
package weight;
public class Weight {
     public static final int SMALLER = -1, EQUAL = 0, LARGER = +1;
     int a;
     public Weight (int a){
          setGram(a);
     private void setGram(int a) {
          this.a = a;
     public int compareTo(Weight wgt) {          
          int status;
          double thisGram = this.getGram();
          double otherGram = wgt.getGram();     
          if (thisGram < otherGram){
               status = SMALLER;          
          }     else if (thisGram == otherGram){
               status = EQUAL;
          }     else {
               status = LARGER;
          return status;          
     private double getGram() {
          return a;
</pre>
Now I created main class:
<pre>
package weight;
public class WeightMain {
     public static void main (String args [] ){     
          Weight wgt1, wgt2;     
          wgt1 = new Weight (2);
          wgt2 = new Weight (3);     
          int result = wgt1.compareTo(wgt2);     
          if (result == Weight.SMALLER){
               System.out.println("wgt1 is smaller than wgt2");
          }     else if (result == Weight.EQUAL){
               System.out.println("wgt1 is Equal to wgt2");
          }     else {
               System.out.println("wgt1 is larger than wgt2");
</pre>
My question is how the compareTo () method is working.It is taking a object of the Weight class as it's parameter but what this.getGram() means and what wgt.getGram() means.How they are getting value.Please give me a little explanation too.
Thanks to spend you valuable time and effort.

Answer 1

public int compareTo(Weight wgt) {          
int status;
double thisGram = this.getGram();
double otherGram = wgt.getGram();     
if (thisGram < otherGram){
status = SMALLER;          
}else if (thisGram == otherGram){
status = EQUAL;
}else {
status = LARGER;
return status;          
private double getGram() {
return a;
}This is obviously not your code, have you taken the time to step through it and to change the arguments to the constructors to Weight in the main method?
The compareTo method takes a reference to a Weight object, it then does a simple comparison on the values returned from the getGram method and returns the appropriate "status" according to the values stored by the setGram method called in the constructor of the object.
"this" refers to the instance of an object inwhich the execution is happening and the wgt is a reference to the other object--in this case the second object that was created in the example code.
This should become clear if you learn how to use your debugger--set a breakpoint, and trace the code execution. Take the time: learn how to use the debugger and play with the code until you understand what is happening.