CODEWITHSUNDEEP
javaarrays
Z.Mike
Z.Mike

Reputation: 11

How to copy/add an Array to a List of Arrays

I'm new in the java, and I've been battling in copying a String array to an ArrayList but it does not store the values, instead stores the address of the array.

String[] newLine = { "name", "location", "price" };
List<String[]> outList = new ArrayList<String[]>();
outList.add(newLine);

for(String[] rows: outList)
{
    System.out.println(row);
}

I get printed

["name", "location", "price"]

If i change the value of newHeader it changes as well in the List.

newLine[0] = "NEW VALUE";
for(String[] rows : outList)
{
    System.out.println(row);
}

Output:

["NEW VALUE", "location", "price"];

How do I just add/copy the values of the Array to the ArrayList?

Maybe It isn't clear but I would like to have something like this at the end:

outList should contain *n* String Arrays e.g.      

["name", "location", "price"] 
["name2", "location2", "price2"]
["name3", "location3", "price3"]
["name4", "location4", "price4"]

Upvotes: 1

Views: 720

Answers (3)

Z.Mike
Z.Mike

Reputation: 11

I have figured out that I can do this:

String[] newLine = { "name", "location", "price" };

List<String[]> outList = new ArrayList<String[]>();

outList.add(new String []{newLine[0], newLine[1], newLine[2]});

Now if I will change the value of newLine it will not alter the outList. But I'm not sure if there is a better way to do this.

Upvotes: 0

Clashsoft
Clashsoft

Reputation: 11882

You can achieve this by storing a copy of the array rather than the array itself:

String[] newLine = { "name", "location", "price" }
String[] copy = newLine.clone();
outList.add(copy);

The clone() method will create a copy of the array that has the same elements and size, but is a different reference / address.

If you now change an element of the original array, the copy doesn't change.

newLine[0] = "NEW VALUE";
System.out.println(Arrays.toString(newLine)); // prints [NEW VALUE, location, price]
System.out.println(Arrays.toString(copy)); // prints [name, location, price]

Upvotes: 2

Woot4Moo
Woot4Moo

Reputation: 24316

you can simply do this:

list.addAll(Arrays.asList(myArray));

Upvotes: 3

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