java.util.List

[r035198x]

From what I understand your question is yes!
But if I track the 'equals' method declaration from my netbeans, it's not pointed to 'equals' what we put in the Entry class. It points to 'equals' in java/lang/Object.java(r/o) .
Maybe that's the reason why I don't get right comparison answer

That's because we did not override the equals method. Instead we overloaded the equals method with another. Change that equals method's signature to

 public boolean equals(Object e)

[shana07]

That's because we did not override the equals method. Instead we overloaded the equals method with another. Change that equals method's signature to

 public boolean equals(Object e)

 cannot find symbol
    [javac] symbol  : variable value
    [javac] location: class java.lang.Object
    [javac] return value != e.value;
java.lang.Error: Unresolved compilation problem: 
	e.value cannot be resolved or is not a field

[r035198x]

 cannot find symbol
[javac] symbol : variable value
[javac] location: class java.lang.Object
[javac] return value != e.value;
java.lang.Error: Unresolved compilation problem: 
	e.value cannot be resolved or is not a field

You'd of course then have to type cast the Object to Event to make that work.

 public boolean equals(Object e) { 
 Event event = (Event)e;
......

[shana07]

sorry, I still don't get the right answer.
I'll update again. thanks for your help.

[r035198x]

sorry, I still don\'t get the right answer.

I\'ll update again. thanks for your help.

Like this

 public boolean equals(Object e) 
{ 

 return value != ((Entry)e).value;
}

What errors are you still getting?

[shana07]

dear friend,
your code works fine.TQ.
Take a look at this it seems mine & yours not much different at glance..hurm

public boolean equals(Object e)  
   { 
      Entry entry = (Entry)e;          
      return value != entry.value;    
   }
   
    public boolean equals(Object e) 
    { 
     return value != ((Entry)e).value;
    }

[shana07]

Friend,
I have other doubt about Lists..please advise.
Is it possible for me to get a Lists with many sub_Lists?
Meaning, under same 'ifs1' field has many ifs1[i], ifs1[2] and etc....Take a look at this:

java.util.List ifs = new java.util.ArrayList(); ---> this field with ifs.size()=4 and no change.

java.util.List ifs1 = new java.util.ArrayList(); ---> this field with ifs1[i].size()=4
ifs1[ii].size=4, .......will increase more & more.

The reason why i'm getting this because
1. I want to make sure/remain the size for ifs1 & 'ifs' is SAME (4)

At this moment, I don't think about the need to create more Lists (because it can be too many Lists),
if you think that I do need, then how to get that in efficient way....thank u

[r035198x]

dear friend,
your code works fine.TQ.
Take a look at this it seems mine & yours not much different at glance..hurm

public boolean equals(Object e) 
{ 
Entry entry = (Entry)e; 
return value != entry.value; 
}
 
public boolean equals(Object e) 
{ 
return value != ((Entry)e).value;
}

Both should work the same way.

[shana07]

Both should work the same way.

Noted. Could you please take a look at my above post. I have other doubt about this Lists please.

[r035198x]

Friend,
I have other doubt about Lists..please advise.
Is it possible for me to get a Lists with many sub_Lists?
Meaning, under same 'ifs1' field has many ifs1[i], ifs1[2] and etc....Take a look at this:

java.util.List ifs = new java.util.ArrayList(); ---> this field with ifs.size()=4 and no change.
 
java.util.List ifs1 = new java.util.ArrayList(); ---> this field with ifs1[i].size()=4
ifs1[ii].size=4, .......will increase more & more.

The reason why i'm getting this because
1. I want to make sure/remain the size for ifs1 & 'ifs' is SAME (4)

At this moment, I don't think about the need to create more Lists (because it can be too many Lists),
if you think that I do need, then how to get that in efficient way....thank u

I'll be frank here. I did not understand all that. All I can say is an ArrayList can contain other lists as elements as well.

 ArrayList list = new ArrayList(); 
list(0) = new ArrayList();

Or

ArrayList<ArrayList> lists = new ArrayList<ArrayList>();

[shana07]

I'll be frank here. I did not understand all that. All I can say is an ArrayList can contain other lists as elements as well.

 ArrayList list = new ArrayList(); 
list(0) = new ArrayList();

Or

ArrayList<ArrayList> lists = new ArrayList<ArrayList>();

:) at least thanks for reading my problem.

From the code, what's mean for list[0]?
How about these codes, what's the difference?

 List ifs = new ArrayList();  vs.  ArrayList ifs = new ArrayList();

If you have an example how to use the ArrayList, please share with me.

[r035198x]

:) at least thanks for reading my problem.

From the code, what's mean for list[0]?
How about these codes, what's the difference?

 List ifs = new ArrayList(); vs. ArrayList ifs = new ArrayList();

If you have an example how to use the ArrayList, please share with me.

List ifs = new ArrayList();

the ArrayList is stored in a variable of type List. Any calls to static variables call variables in the List interface. You can also assign other type of Lists e.g LinkedList to be stored by the variable ifs whereas with

ArrayList ifs = new ArrayList();

you cannot make ifs store a reference to any object of type that is not a subclass of ArrayList. You'll probably not be able to notice the difference.

[shana07]

List ifs = new ArrayList();

the ArrayList is stored in a variable of type List. Any calls to static variables call variables in the List interface. You can also assign other type of Lists e.g LinkedList to be stored by the variable ifs whereas with

ArrayList ifs = new ArrayList();

you cannot make ifs store a reference to any object of type that is not a subclass of ArrayList. You'll probably not be able to notice the difference.

I've tried run program by replacing

ArrayList ifs1 = new java.util.ArrayList();

in my program, yes I can't see the difference. the entries are the same.
you cannot make ifs store a reference to any object of type that is not a subclass of ArrayList.
What's the subclass here mean?

[r035198x]

I've tried run program by replacing

ArrayList ifs1 = new java.util.ArrayList();

in my program, yes I can't see the difference. the entries are the same.
you cannot make ifs store a reference to any object of type that is not a subclass of ArrayList.
What's the subclass here mean?

A class that inherits from the class ArrayList. (That's if you know any inheritance)

if you have

 class B { 
}

and

 class A extends B { 
}

You can do

B b = new A();

but you cannot do

 A a = new B();

In this case your B is list and your A is ArrayList except for that List is actually an interface rather than a class.

[shana07]

A class that inherits from the class ArrayList. (That's if you know any inheritance)
if you have

 class B { 
}

and

 class A extends B { 
}

You can do

B b = new A();

but you cannot do

 A a = new B();

In this case your B is list and your A is ArrayList except for that List is actually an interface rather than a class.

TQ.Pretty understood List now and also I read List is an interface from a Collection.
Then, how about an ArrayList can contain other lists .....as what you said?
[QUOTE=r035198x] All I can say is an ArrayList can contain other lists as elements as well.

 ArrayList list = new ArrayList(); 
list(0) = new ArrayList();

Coz, my aim here is to create many ArrayList (or list - not sure) with the same variable (ifs1) in loop.
again, not sure this is possible or not.....