从输入文件图Java添加顶点

Question

I am attempting to implement a graph in Java. I want to add vertex from the input file. Here is my code:

Scanner input = new Scanner(System.in);

try
{
    ArrayList<String> Alist= new ArrayList <String>();
    FileReader fr= new FileReader("/home/vanhook/Desktop/city.txt");
    BufferedReader reader= new BufferedReader(fr);

    String line;
    while ((line=reader.readLine()) !=null)
    {
        //Add to ArrayList
        Alist.add(line);            
    }

    //print the city
    for (int z = 0; z < 7; z++)
    {
        System.out.println(Alist.get(z));
    }

    /*
    Here is the code to add vertex manually 
    Graph graphNew = new Graph();
    graphNew.insertVertex("Jakarta");           //0
    graphNew.insertVertex("Bandung");           //1
    graphNew.insertVertex("Semarang");          //2
    graphNew.insertVertex("Surabaya");          //3
    graphNew.insertVertex("Madura");            //4
    graphNew.insertVertex("Bali");              //5
     */

Here is the city.txt:

Jakarta
Bandung
Semarang
Surabaya
Madura
Bali

What is the code to replace manually insert vertex with the input file? I try to use looping like this:

for (int z = 1; z < 7; z++)
{
    graphNew.inserVertex(Alist.get(z));
}

but I got an error.

Answer 1

for (z=1;z<7;z++){
graphNew.inserVertex(Alist.get(z));
}

Indices in java are 0 based, not 1 based.

That means the first index is 0 , and the last index (you can access) is Alist.length() - 1 , which is 5 in your case.

As side notes:

1. You should prefer a for each loop over an old style index loop:

   for (String city : Alist) graphNew.inserVertex(city);

2. variables in java start with lower case letter ( aList instead of Alist ). This is not enforced by compiler, but is a convention.