Loop through multiple arraylists and get elements

Question

public static void main(String[] args)
{
        loadDependencies ld = new loadDependencies();
        List<String> ls = ld.loadDependenciesFromPom();  
        getAvailableHigherVersions ah = new getAvailableHigherVersions();

        List<List<String>> vl = ah.versionListOnly();
        String previousVersion=null;

        for ( int a=0; a<vl.size();a++) {
            List<String> tmp = vl.get(a);
            for(int i=0; i<ls.size();i++){
                String firstE = ls.get(i);
                for(int j=0;j<tmp.size();j++) {
                    if (i==0  && j==0){
                        //xu.versionUpdate(previousVersion, tmp.get(j));
                        //String previousVersiontt = ls.get(i);
                        System.out.println(firstE + "----" + tmp.get(j));
                    }
                        /*xu.versionUpdate(previousVersion, tmp.get(j));
                        previousVersion=tmp.get(j);*/
                        //System.out.println(previousVersion+"-"+tmp.get(j));
                      //  previousVersion = tmp.get(j);

                }
            }
        }
}

"ls" is a String list. It contains like this

[1,4,5,7]

"vl"is a List of string list. It contains like this

[[1.5,1.6,1.7],[4.1,4.2,4.3],[5.1,5.2],[7.1,7.4]]

what I need to do is first take the 1st element of ls list

1

then i need to get the first element in the vl list

[1.5,1.6,1.7]

then output should be

[1,1.5]

then the next output would be

[1.5,1.6]

likewise iterate through the array. Then next take the 2nd element of ls

4

then it should go like 4,4.1 then 4.1,4.2 likewise until the ls is empty. I tried above code but some times it iterate multiple times. Any hint to fix this issue?

It has nothing to do with your question but please use the naming conventions: A classname should start with an uppercase letter. It looks like method calls this way. — Robert Kock
– Robert Kock, Commented Apr 1, 2019 at 16:24
Hints: use forEach type of loops instead, read documentation for the String class to find suitable methods for filtering the right sub-elements — Joakim Danielson
– Joakim Danielson, Commented Apr 1, 2019 at 16:27
The number of elements in ls is always equal to the number of elements in the (outer) list vl? — Robert Kock
– Robert Kock, Commented Apr 1, 2019 at 16:28
What should be printed after [1.6, 1.7]? [4, 4.1] or [1.7, 4]? — Robert Kock
– Robert Kock, Commented Apr 1, 2019 at 16:34

Robert Kock · Accepted Answer · 2019-04-01 16:43:56Z

1

So if I understood well, you want something like this:

for (int a = 0; a < ls.size(); a++)
{
  // Get first element
  String firstE = ls.get(a);

  // Get corresponding vl elements
  List<String> vls = vl.get(a);

  // Now print the elements
  // The first element of vl should be preceeded by the corresponding element in ls
  // The others by the predecessor in the same array
  for (int b = 0; b < vls.size(); b++)
  {
    System.out.print("[");
    if (b == 0)
      System.out.print(firstE);
    else
      System.out.print(vls.get(b - 1));
    System.out.println(", " + vls.get(b) + "]");
  }

}

answered Apr 1, 2019 at 16:43

Robert Kock

6,0482 gold badges14 silver badges23 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

vijay · Accepted Answer · 2019-04-01 16:46:41Z

1

for(int i=0;i<ls.size();i++){
   List<String> tmp = vl.get(i);
   System.out.println(ls.get(i)+" "+temp.get(0));
   for(int j=1;j<tem.size()-1;j++){
      System.out.println(temp.get(j)+" "+temp.get(j+1));
   }       
}

answered Apr 1, 2019 at 16:46

vijay

1871 silver badge10 bronze badges

Comments

pethryth · Accepted Answer · 2019-04-01 16:43:40Z

0

for ( int a=0; a<vl.size();a++) {
        List<String> tmp = vl.get(a);
        String firstE = ls.get(a);
            for (int j = 0; j < tmp.size(); j++) {
                if (j == 0) {
                    //xu.versionUpdate(previousVersion, tmp.get(j));
                    //String previousVersiontt = ls.get(i);
                    System.out.println(firstE + "----" + tmp.get(j));
                }
                    /*xu.versionUpdate(previousVersion, tmp.get(j));
                    previousVersion=tmp.get(j);*/
                //System.out.println(previousVersion+"-"+tmp.get(j));
                //  previousVersion = tmp.get(j);

        }
    }
}

answered Apr 1, 2019 at 16:43

pethryth

565 bronze badges

Collectives™ on Stack Overflow

Loop through multiple arraylists and get elements

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related