kaushik vira

import java.util.HashSet; import java.util.Set; public class A { public String a; int c; short b; public A(String a1, int c1, short b1) { a = a1; c = c1; b = b1; } public int hashCode() { return a.length() * c; } public boolean equals(Object o) { return ((A)o).a.length() * ((A)o).b * ((A)o).c == this.a.length() * this.b * this.c; } @Override public String toString() { return "code="+this.a+",b="+this.b+",c="+this.c; } public static void main(String[] args) { A a1 = new A("a",3,(short) 2); A a2 = new A("a",3,(short) 3); Set<A> set = new HashSet<A>(); System.out.println(set.add(a1)); System.out.println(set.add(a2)); for(A a:set){ System.out.println(a); } } }

Output:-
true
true
code=a,b=3,c=3
code=a,b=2,c=3

Above example may help to understand the answer. In your current example hash code method implementation is not strong. but equals method making sure that object equality.

Don`t worry, it`s take some time. My information also update in 2 week.

Try to run the URL using browser.... check that your URL is valid or not..

Then you get clear idea that, where is gap.

Hay amarkirt

request.getSession(true) is called ... // ontainer returns the pre-existing / current session.

HFSJ First Edition - page 233

Then I am moving with First Edition.. and as i got PDF of 2nd edition.. so. will just go though it at last..

Thanks you for all the replies.. I got directions..

Hello Nishan,

I have cleared my SCJP tomorrow, i want to check status of my Exam.. but when i give my proper details to get my account still it`s not confining me..

I guess this section is not proper to discuss this.. but can any one point me where should i post or look for more details.

Hay,

Is there lot of changes.. I am new for SCWCD, you can say born today. i have read HFSJ last year. Should i go with First Edition or i should buy newer one..

Hello Ranchers,

I have just completed my SCJP, and now i want to jump in SCWCD. . I want some pointer how to start. What are the books available and from them which are Preferred.. Which are the simulator available.. and what would be best strategy to crack SCWCD with higher score..

Please Don`t send me list of 100 simulator.. I am looking for inputs that talks about the preferred material that got highlighted based on the past Ranching experience.


Thanks in Advance..

not based on my expectation.. but i did mistake. i solved all question in just 2 hours and submit paper with out review the answers...

Hello Raymond,

Your base assumption is wrong here.

know c2 is not null because,it is referencing to a CardBoard object.

if you look in to go method implementation.. when you call c1.go(c2) c2 become GC eligible.

4 Object is eligible for GC - 2 CardBoard and 2 Short object


Please correct me rancher if I am wrong..

Change your Car implementation with following code..


public class Car extends Vehicle implements Serializable { public Car(String make, String color, int weight) { this.make = make; this.color = color; this.weight = weight; } }

if you observe your code, you had define new property weight with hides the property member from Vehicle. so in your code there are two member having same name.

one is

weight - > Vehicle - which not cover under serialization and it`s value is assign by constructor at time of deserialization
weight - > Car - which cover under serialization so normal deserialization will work on it.

Yes.. Color.colorMap will be null..


If try to compile and run following code it will run .. because you are just declaring Enum

import java.util.HashMap; import java.util.Map; class tst { enum Color { RED, GREEN, BLUE; static final Map<String,Color> colorMap = new HashMap<String,Color>(); Color() { [b] Color.colorMap.[/b]put(toString(), this); } } public static void main(String[] args){ }}

but when you try to use Enum.. you will get null Pointer at run time..

public static void main(String[] args){ System.out.printlnColor.GREEN); }}

Same case with me.. I was using My Eclipse for faster work..

Your question is very basic.. it will be very hard to expain all the things..

better you go through K&B Chapter 6 - Topic sorting Collections , Comparable Interface and Comparator interface - page (549 -555). it will give you clear idea how flow goes..

1:- Enum must not declare in method.. - So taking out enum from main method..

import java.util.HashMap; import java.util.Map; class tst { enum Color { RED, GREEN, BLUE; static final Map<String,Color> colorMap = new HashMap<String,Color>(); Color() { [b] Color.colorMap.[/b]put(toString(), this); } } public static void main(String[] args){ }}

2:- colorMap is static member.. so you should refer it as Color.colorMap.. and your code will compile fine also run fine....


But if you add one line in main() then below quote come in picture..

public static void main(String[] args){ System.out.println(Color.BLUE); }}

Static initialization of this enum type would throw a NullPointerException because the static variable colorMap is uninitialized when the constructors for the enum constants run. The restriction above ensures that such code won't compile