Set value in ArrayList<Object[]>

Question

It's been a while since my data structures class and I'm having a hard time figuring this one out. I know that if I want to get the value from an ArrayList of Object[] I can use

nameOfArrayList.get(row)[col];

but I can't seem to figure out, or find on the web, how to set a value.

Would I have to create a new object and set it to nameOfArrayList.get(row), alter the value and then use

nameOfArrayList.set(row,Object[])?

Adam Zalcman · Accepted Answer · 2012-03-04 20:12:57Z

6

Try this:

nameOfArray.get(row)[col] = ...;

This sets a new value at index col of the array at index row in the nameOfArray ArrayList.

If you want to put a new array into nameOfArray at position row, try this:

nameOfArray.set(row, new Object[]);

This creates a new array of objects and puts it under index row in nameOfArray. See ArrayList.set().

answered Mar 4, 2012 at 20:12

Adam Zalcman

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2 Comments

Geoff Over a year ago

Wow, that is odd to me. I wouldn't think an accessor method would actually be a mutator. I can't believe it was that simple. I see how it makes sense now, in essence it's getting the Object array through the nameOfArray.get() and the brackets with an int contained is the same as using the Object[int]= command. Thanks!

David Harkness Over a year ago

@Geoff - get is merely returning the array, a read-only operation. What you do with the array after that is your business. :) The above is equivalent to Object[] arr = nameOfArray.get(row); arr[col] = ...;

S.P. · Accepted Answer · 2012-03-04 22:51:37Z

0

Here is a simple basic run.

If you want to add the Object at the end you can just use something like

nameOfArray.add(<object array>)

Else if you want it at a specified index something like above

nameOfArray.set(index, <object array>)

Reference

<object array>.get(row)[col] = change value

edited Mar 4, 2012 at 22:51

answered Mar 4, 2012 at 20:15

S.P.

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2 Comments

DNA Over a year ago

That's setting an entire row. I think the OP wants to set a particular row,column.

David Harkness Over a year ago

The first line to append should be nameOfArray.add(<object array>) instead of set. The latter always requires an index.

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