Object Arrays

[Joel Christophel]

public class Chapter_19 {
  public static void main (String args[]) {
    Circle cir[] = new Circle [500];
    Circle cir1[] = new Circle [500];
    cir[0] = new Circle();
    cir[0].setRadius(50);
    System.out.println(cir[0].getRadius());
    cir1 = cir;
    System.out.println(cir1[0].getRadius());
  }
}

class Circle {
  public int radius;
  
  public void setRadius(int rad)
  { rad = radius; }
  
  public int getRadius()
  { return radius; }
}

The printout is:
0
0

Why is this? Didn't I just set both radii to 50? It acts like it's ignoring the method calls from class Circle.

[Matthew Brown]

Have a closer look at your Circle.setRadius method. It isn't doing what you think it's doing.

[Joel Christophel]

Thanks once again

[Ove Lindström]

Matthew Brown wrote:Have a closer look at your Circle.setRadius method. It isn't doing what you think it's doing.

Classic... I once spent 3 days trying to find one of those errors. ;)

[John Jai]

Ove Lindström wrote:Classic... I once spent 3 days trying to find one of those errors. ;)

Yes... given that compiler also don't warn on such situations.

[Ove Lindström]

John Jai wrote:

Ove Lindström wrote:Classic... I once spent 3 days trying to find one of those errors. ;)

Yes... given that compiler also don't warn on such situations.

Exactly. But both PMD and FindBugs detects it so they are used in most of my continuous integration environments nowadays.

[ali Dada]

you are declaring:

int radius;

but you are assigning in setRadius as

 public void setRadius(int rad)  
  {
      rad = radius; 
   }  

By default the variable which is integer is 0; so it displays 0;
write as:

 public void setRadius(int rad)  
  {
      radius=rad; 
   }