CODEWITHSUNDEEP
javaarraylist
Vaggos B
Vaggos B

Reputation: 5

How to copy the contents of an ArrayList in another ArrayList

public boolean isConnectedTo(Suspect aSuspect){

    boolean flag = false;
    Registry tempRegistry = new Registry();
    ArrayList<Communication> TempComms = new ArrayList<Communication>(tempRegistry.GetComms());


    for(Communication comms : TempComms) {
        System.out.println("here");
        for(String PhoneNums : phoneNumbers){
            if(PhoneNums.equals(comms.GetTransmitter())) {
                for(String numbers : aSuspect.getNumbersList()) {
                    if(numbers.equals(comms.GetReceiver())) 
                        flag = true;
                    }

                }
            }
    }
    return flag;

}

So I am trying to create a program that among other things, it will search two ArrayLists(TempComs and phoneNumbers) and it will return true or false whether a string in the first is the same with a string in the second or not. I create the new ArrayList TempComms with the method tempRegistry.GetComms(). GetComms() is a method in another class, (class Registry) and has just a return communications; command, communications is an ArrayList in the class Registry.(The ArrayList phoneNumbers is an arrayList of the class the code is into.) So normally with with

ArrayList<Communication> TempComms = new ArrayList<Communication>(tempRegistry.GetComms());

the ArrayList TempComms must be the same with ArrayList communication that exists in the other class. But I figured out that for some reason the problem is in TempComms, because the first for is never running(For that reason I used System.out.println("here"); but it never printed). I searched and tried a lot to find the solution of this problem of my own, but I didn't manage to make some progress, so I would be grateful if someone who knows where's the problem or what I do wrong tell me about it. Thanks anyway.

Upvotes: 0

Views: 110

Answers (1)

Minudika
Minudika

Reputation: 851

You are creating a new instance of the Registry which contains a list (comms).

Registry tempRegistry = new Registry();

Then you are trying to get that comm list by calling tempRegistry.GetComms() .

Unless you are populating this communication list in the constructor Registry() (not only instantiating, you should add some entries as well), that list will be empty when for loop is called.

(Because you are clearly NOT populating it after creating the instance tempRegistry and before calling the for loop.

ArrayList<Communication> TempComms = new ArrayList<Communication>(tempRegistry.GetComms());


    for(Communication comms : TempComms) {

Therefore, the TempComms list is also an empty list. Which is why the inside code of the for loop is not executing.

Upvotes: 2

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