Reference on an 2D-Array-Element

Question

public class ReferenceTest {
    public static void main(String[] args) {

        String[][] names = {{"George","Hampton"},{"Marc", "Empten"},{"Levin", "Lian"}};

        Object oneperson; //Reference to one object of the 2D Array

        oneperson = names[1]; 

        //Output should be Marc Empten
        System.out.println(oneperson.toString()); //[Ljava.lang.String;@11890d

    }
}

Is it possible to create such a reference in java? So I can save an array-element(

{"Marc","Empten"}

) from the array?

So I can use only the oneperson variable to give out the "Marc Empten"? I have no Idea how to realise this. Is it even possible?

Syam S · Accepted Answer · 2014-07-22 09:41:28Z

2

If you want to just print an array use Arrays.toString() method. But the better approach her would be to make a class Name which hold both parts. Then use an array list to store the names. Like

class Name{
    private String firstName;
    private String lastName;

    public Name(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Override
    public String toString() {
        return "{" + firstName + ", " + lastName
                + "}";
    }
    // Getters & Setters
}

public class Sample {

    public static void main(String[] args) throws JsonProcessingException {
        List<Name> names = new ArrayList<Name>(Arrays.asList(new Name[] { new Name("George","Hampton"), new Name("Marc", "Empten"), new Name("Levin", "Lian")}));
        System.out.println(names.get(1)); // Prints {Marc, Empten}

    }
}

answered Jul 22, 2014 at 9:41

Syam S

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5 Comments

Pascal Over a year ago

so i must always use names.get(number) i wanna use a "object" like feuerball it did

stevecross Over a year ago

This is almost the same as names[number]. Lists have the benefit that you have no constraints in the size.

Syam S Over a year ago

List is basically an array underneath the covers. So its similar to feuerball number except it can grow as an when you add items. I didnt full understand what you meant by "i wanna use a object". Did you mean you need to do this as an array?

Pascal Over a year ago

no i want to have a reference object like evry other variable for explizit one element of an array or arraylist...

Syam S Over a year ago

Yes. That what the indexing does. It returns the element at index 1. Which is equivalent to Name oneperson = names.get(1); or you could like Object oneperson = names.get(1);.

Sanjeev · Accepted Answer · 2014-07-22 09:39:09Z

1

Do it like this:

System.out.println(Arrays.toString((Object[])oneperson));

answered Jul 22, 2014 at 9:39

Sanjeev

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4 Comments

stevecross Over a year ago

This does not work because oneperson is an Object and not an array.

stevecross Over a year ago

Additionally it would print [Marc, Empten] if it was working.

Pascal Over a year ago

with a cast this is possible :

Sanjeev Over a year ago

Added Cast to an array

stevecross · Accepted Answer · 2014-07-22 09:51:30Z

You would have to write something like this:

public class ReferenceTest {
    public static void main(String[] args) {
        // An array of arrays of Strings
        String[][] names = {{"George","Hampton"},{"Marc", "Empten"},{"Levin", "Lian"}};
        // An array of Strings
        String[] marc = names[1]; 
        //Output is Marc Empten
        System.out.println(marc[0] + " " + marc[1]);
    }
}

This only works if you know for sure that the inner arrays always contain 2 elements. If not you would have to use a loop to print the name for example (note that the last name has 3 parts):

final String[][] names =
    { { "George", "Hampton" }, { "Marc", "Empten" }, { "Levin", "Lian" }, { "John", "James", "Rambo" } };

for (final String[] name : names) {
    for (final String partial : name) {
        System.out.print(partial);
        System.out.print(" ");
    }

    System.out.println();
}

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