Problems with ArrayList<ArrayList<Integer>> .. JAVA

Question

It is an arraylist of arraylists of integers. I'm still running into an issue though when I try to compile. The command prompt says "incompatible types." I know for sure that all the function calls are correct (i.e.: .getStart(), .getEnd(), etc. - I wrote those classes and have tested them thoroughly.) Btw, "permOfEdges" is: ArrayList <ArrayList<Edge>> (Edge being a class I wrote.)

Since it's: visited.get(-).get(-), it says the second .get(-) should be a variable not a value. I'm confused on what it means since it's an arraylist of arraylists.

Code for arraylist of arraylists:

ArrayList<ArrayList<Integer>> visited = new ArrayList<ArrayList<Integer>>();
for(int i = 1; i < permOfEdges.size(); i++)
    {
        for(int j = 0; j < permOfEdges.get(i).size(); j++)
        {
            visited.get(i).get(j) = 0;  // this is to initialize the entire thing to only contain zeros
        }
    }
    for(int i = 1; i < permOfEdges.size(); i++)
    {
        for(Edge point: permOfEdges.get(i))
        {   
            if((visited.get(point.getEnd()).get(point.getStart()) == 0) && visited.get(point.getStart().get(point.getEnd()) == 0))  // means NOT visited yet
            {
                writer.println(point.getStart() + " " + point.getEnd() + " " + point.getDistance() + " " + point.getPrice());
            }
            visited.get(point.getStart()).get(point.getEnd()) = 1;
            visited.get(point.getEnd()).get(point.getStart()) = 1;
        }
    }

    writer.close();

The error reads: 1. unexpected types: visited.get(i).get*(j) = 0 (* = where the ^ was in the command prompt) required: variable found: value

int cannot be dereferenced if((visited.get(point.getEnd()).get*(point.getStart()) == 0) &&...)
and 4. both of these errors are the same as the first one except it focuses on the two lines where I assign visited.get(..).get(..) = 1

Any help would be much appreciated! Thank you!

**permOfEdges is ArrayList<ArrayList<Edge>> (Edge being a class I wrote) — Nupur
– Nupur, Commented Mar 26, 2015 at 23:07
The only error I have right now is that it doesn't like the if statement. It says that it is "int cannot be dereferenced" do you know what that means? @jangroth — Nupur
– Nupur, Commented Mar 26, 2015 at 23:17

Stack Exchange Broke The Law · Accepted Answer · 2015-03-26 23:12:37Z

1

You cannot assign to the result of a method call. This is wrong:

visited.get(i).get(j) = 1;

and you presumably meant:

visited.get(i).set(j, 1);

edited Mar 26, 2015 at 23:12

answered Mar 26, 2015 at 23:07

Stack Exchange Broke The Law

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8 Comments

Nupur Over a year ago

Also, do you have any idea about why the if statement would be throwing an error?

Stack Exchange Broke The Law Over a year ago

@Nupur whoops, it's called set. (put is for maps)

Nupur Over a year ago

Thank you! I realized, it shouldn't be .put(), it should be .set(). So I just have one error now and it is due to the if statement.

Nupur Over a year ago

Do you have any ideas about why it would say that I am "dereferencing" the int??

Stack Exchange Broke The Law Over a year ago

@Nupur Because you are trying to call a method on an int, in another place. Also, one question per question...

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