saloni jhanwar

Panagiotis Kalogeropoulos wrote:I thought your question was about why to use iterators since we have the for loop (scratching my head......). Maybe the expression "pros and cons" that I used was not the best, but in that link you can see why and when you should use the for loop or an iterator. I don't know if that still answers your question (scratching my head again....).

If you really know that your that link has my answer and you are sure then why don't you post that answer of that document ?

Hi folk
My question is that if i can iterate an ArrayList using for loop then what does iterator() make difference here ?

Manoj Kumar Jain wrote:This code will not compile, not because the array is uninitialized. Array elements are initialized with their default value that is 0 for integers.
This will fail because there is a local variable size that is not initialized before using and that is line no. 5

I know already that but i think elements arr[0]-[9] are also local variables.

class SomeClass{     public static void main(String args[]){       int size ;       int[] arr = new int[10];       for (int i = 0 ; i < size ; ++i) System.out.println(arr[i]);    //not fail why ? System.out.println(size); //failed } }

I thought it will fail to compile because array is uninitialized.

Thanks everyone

class Multi { public static void main(String[] args) { int[][] i=new int[3][]; i[0]=new int[2]; i[1]=new int[3]; i[0][0]=1; i[0][1]=2; i[1][0]=3; i[1][1]=4; i[1][2]=5; for(int[] j:i){ //Various way to iterate it ?? } } }

Campbell Ritchie wrote:How old is your book? Have a look through all those classes for valueOf methods, and I think you will find more than there are in your table.

My book is new, i have K&B 6,and that snap was from k&b 6.

Thanks Henry for new logic.

Matthew Brown wrote:You're trying to cast am Integer to a Byte. They aren't compatible, they're on different inheritance branches. That would only make sense if Byte was a subclass of Integer.

Then i were expecting ClassCastException.

class Example { public static void main(String[] args) { Integer i=new Integer(54); int j=i;// compile fine byte b=(Byte)i;//compile error why i have done casting Byte type } }
F:\Wrapper classes>javac Example.java
Example.java:11: error: inconvertible types
byte b2=(Byte)f2;

Why inconvertible ? After casting it should be convertible

I got confuse becaude even K&B showing no parseXxx method for Boolean and Character class.

Matthew Brown wrote:What makes you think the method doesn't exist? It's there in the documentation.

http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/Boolean.html

Whereas I know there are only six parseXxx() methods for numeric type of primitives.
There is no method for Boolean class then how thiscode is working and printing even true
class Example2 { public static void main(String[] args) { boolean B=Boolean.parseBoolean("true"); System.out.println(B); } }
Output:true