Book Answer vs JVM, Same Code Different Output?

[Jerick Almonina]

Hi, I'm a newly registered member here, I don't know where to post this post but for a try, I wrote this. Kindly correct me if my my post particularly this one is inappropriate for this room(General Java).

I'm reading the Head First Java book and I'm on chapter 3 already(Know your Variables), as I finish the required exercises( the one with the shoe icon),I check what I've done in contrast to the answer key and it is right, but when I try to actually run the code it turns out to be wrong because of the ouput.

This is the code the I've Done(From the Code Magnet):

class TestArrays{
 public static void main (String[] args){
int y = 0;
int[] index = new int[4];
index[0] = 1;
index[0] = 3;
index[2] = 0;
index[3] = 2;
String[] island = new String[4];
island[0] = "Bermuda";
island[1] = "Fiji";
island[2] = "Azores";
island[3] = "Conzumel";
int ref;
while(y < 4){
ref = index[y];
System.out.print("isLand = ");
System.out.println(island[ref]);
y = y + 1;
}
  }
}

when i ran the above code, looks like this:
Island = Conzumel
Island = Bermuda
Island = Bermuda
Island = Azores

It is Suppose to output like this:
isLand = Fiji
isLand = Cozumel
isLand = Bermuda
isLand = Azores


My JVM version is:
java version "1.6.0_07"
Java(TM) SE Runtime Environment (build 1.6.0_07-b06)
Java HotSpot(TM) Client VM (build 10.0-b23, mixed mode, sharing)


Is there a problem with the book or the compiler or jvm?

[Vijitha Kumara]

Nothing wrong with the output you are getting. That is the output according to the code you are given.

      int[] index = new int[4];
index[0] = 1;
                index[0] = 3;
 index[2] = 0;
index[3] = 2;
       String[] island = new String[4]; 
island[0] = "Bermuda";
island[1] = "Fiji";
island[2] = "Azores";
island[3] = "Conzumel";  

index[1] value will be 0. Since you are not assigning anything to that position (It defaults to 0 because the array type is int). So when y's value is 1 & 2 it will output --> Bermuda (index[1]/index[2] -->0), So ref--> 0 and island[0] --> Bermuda

Check the value of ref variable in each iteration. Then you will see this.

Hope this helps.
[ September 02, 2008: Message edited by: Vijitha Kumara ]

[Campbell Ritchie]

And welcome to JavaRanch

[Ernest Friedman-Hill]

I suspect you copied the code wrong, or the book has a typo; the line

index[0] = 3;

is probably supposed to be

index[1] = 3;

which would then give the right output.

[Jerick Almonina]

Yes I got it, I missed typed the code in contrast to my writing on my notes. Thank for helping out guys.

I'm just new here, I took your advices as a warm welcome here. Next time I'll be keen thanks again guys