Java-如何获取数组中给定元素的索引

Question

I have an array of contacts like so :

public class Application {

private Scanner input;
private Contact[] contacts;
private int ArrayNum;

public Application() {
    input = new Scanner(System.in);
    contacts = new Contact[5];
    ArrayNum = 0;

}

And what I want to do is enter a name of someone on the contacts list and if they are found on their list return their index like so:

System.out.println("Who do you want to remove?");

            String name = input.nextLine();

            for(Contact c: contacts){
                if(c.getName().equals(name)){

                    //Get the index here
                }
            }

I tried researching this but no answer or guide seems to be very clear on this so I'm hoping that someone can explain this for me.

Thank you for looking

Answer 1

for(int index = 0; index < contacts.length; index++) {
    if(contacts[index].getName().equals(name)) {
        // use the index here
    }
}

I don't think this code snippet needs any further explanation.

Answer 2

Use a for loop that uses a counter instead.

for(int i = 0; i < contacts.length, i++) {
    if(contacts[i].getName().equals(name)) {
        // do something with the index, i
    }
}

Answer 3

You could use a counter

System.out.println("Who do you want to remove?");

        String name = input.nextLine();
        int remove_index = -1;
        for(int i=0; i<contacts.length; i++){
            Contact c = contacts[i];
            if(c.getName().equals(name)){
                remove_index =i;
            }
        }

Answer 4

Another alternative that may be helpful down the line is to use an ArrayList<Contact> instead of a c-style array ( Contact[] ). This class might add more handling complexity than it's worth, but it includes a lot of useful extra methods, including an int indexOf(<T> object) where <T> is the type you specified in your declaration (ie, Contact for ArrayList<Contact> contacts ).

Answer 5

Bad idea! You can't do that seriously, if you have an array. Of course you can set an index to null, but then you have to search for a null entry to reference a new contact within the array. Note: you have an Iterator while writing

for(Contact c: contacts){...

So one option is to iterate by index, but it's a bad option. Better make your Array a Set. Then you might write:

for (Iterator<Contact> iter = mySet.iterator();iter.hasNext();) {
    final Contact next = iter.next();
    if(next.getName() == "NAME") {
         iter.remove();
         break;
    }

Always use Iterator.remove()! Otherwise you will get Exceptions earlier than you wish :D