java - How do i access a specific object from with in the class it was created from -
im not going paste whole entire code here problem. keep things simple ill make code right here problem.
okay have class called "exampleclass" has integer variable called "number" example , "number" has , set method. question is: if have multiple objects of "exampleclass" how specific object out of multiple objects can access specific object inside "exampleclass".
"exampleclass" below
public class exampleclass{ public int number; public int getnumber() { return number; } public void setnumber(int number) { this.number = number; } }
assuming number makes instance of class "unique" purpose of comparison, should consider overriding equals , hashcode methods.
that way, you'll able find instances of class within collection such arraylist using indexof(object o);
for example:
public class exampleclass { private int number; public exampleclass(int number) { this.number = number; } public int getnumber() { return number; } public void setnumber(int number) { this.number = number; } @override public boolean equals(object other) { boolean isequal = false; if (other instanceof exampleclass) { exampleclass otherec = (exampleclass)other; isequal = number == otherec.number; } return isequal; } @override public int hashcode() { return number; } }
and
public static void main(string[] args) { list<exampleclass> list = new arraylist<exampleclass>(); exampleclass ec1 = new exampleclass(1); list.add(ec1); list.add(new exampleclass(3)); list.add(new exampleclass(102)); system.out.println(list.indexof(new exampleclass(3))); system.out.println(list.indexof(new exampleclass(1))); system.out.println(list.indexof(ec1)); system.out.println(list.indexof(new exampleclass(5))); }
will produce following output:
1 0 0 -1
please here more information on why should override equals , hashcode objects want store in collections:
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