Thread: Retrieve desired values from a HashMap to print duplicate value

Please consider the following code:

public static void main(String[] args) {
 
List<String> fileContents = new ArrayList<String>();
 
fileContents.add("AB1011");
fileContents.add("AB1012");
fileContents.add("AB1013");
fileContents.add("AB1014");
fileContents.add("AB1015");
fileContents.add("AB1015");
fileContents.add("AB1012");
;
String[] sample_letter = { "A1", "E2", "G1", "C3", "B1", "F2", "H1", "D3", "C1", "G2", "A2", "E3", "D1", "H2",
"B2", "F3", "E1", "A3", "C2", "G3", "F1", "B3", "D2", "H3", "A4", "E5", "G4", "C6", "B4", "F5", "H4",
"D6", "C4", "G5", "A5", "E6", "D4", "H5", "B5", "F6", "E4", "A6", "C5", "G6", "F4", "B6", "D5", "H6",
"A7", "E8", "G7", "C9", "B7", "F8", "H7", "D9", "C7", "G8", "A8", "E9", "D7", "H8", "B8", "F9", "E7",
"A9", "C8", "G9", "F7", "B9", "D8", "H9", "A10", "E11", "G10", "C12", "B10", "F11", "H10", "D12", "C10",
"G11", "A11", "E12", "D10", "H11", "B11", "F12", "E10", "A12", "C11", "G12", "F10", "B12", "D11",
"H12" };
 
List<String[]> rows = new ArrayList<String[]>();
 
Map<String, List<Integer>> mapDups = new HashMap<>(); // name, list of line numbers
 
Map<Integer, Integer> indexMap = new HashMap<>(); // line number, index of the line number
 
ArrayList<Integer> firstPositionofOriginalCase = new ArrayList<Integer>();
ArrayList<Integer> duplicatePositionofOriginalCase = new ArrayList<Integer>();
 
for (int i = 0; i < fileContents.size(); i++) {
String name = fileContents.get(i);
List<Integer> lineNos = mapDups.get(name);
if (lineNos != null) {
 
for (int j = 0; j < lineNos.size(); j++) {
int lineNo = lineNos.get(j);
 
indexMap.put(lineNo, i);
duplicatePositionofOriginalCase.add(i);
firstPositionofOriginalCase.add(lineNo);
 
}
}
 
if (lineNos == null)
lineNos = new ArrayList<Integer>();
lineNos.add(i);
mapDups.put(name, lineNos);
}
 
for (var entry : mapDups.entrySet()) {
System.out.println(entry.getKey() + "|" + entry.getValue());
}
 
// Map for storing
 
for (int i = 0; i < fileContents.size(); i++) {
String replicate = "         "; // placeholder 9 spaces for when a duplicate is not found
String Aux = "0";
 
String[] rowInfo = { fileContents.get(i) + "_" + sample_letter[i], replicate, sample_letter[i] };
 
System.out.println("Adding: " + fileContents.get(i) + "_" + sample_letter[i] + " | " + replicate + " | "
+ sample_letter[i] + "|" + Aux);
 
rows.add(rowInfo);
}
 
}

The above code prints the following:

AB1015|[4, 5]
AB1011|[0]
AB1012|[1, 6]
AB1013|[2]
AB1014|[3]
Adding: AB1011_A1 |           | A1|0
Adding: AB1012_E2 |           | E2|0
Adding: AB1013_G1 |           | G1|0
Adding: AB1014_C3 |           | C3|0
Adding: AB1015_B1 |           | B1|0
Adding: AB1015_F2 |           | F2|0
Adding: AB1012_H1 |           | H1|0

And I am looking for the following output.

Adding: AB1011_A1 |           | A1|0
Adding: AB1012_E2 |  AB1012_H1         | E2|0
Adding: AB1013_G1 |           | G1|0
Adding: AB1014_C3 |           | C3|0
Adding: AB1015_B1 | AB1015_F2          | B1|0
Adding: AB1015_F2 |           | F2|0
Adding: AB1012_H1 |           | H1|0

Explanation of what I'm looking for:

As shown above, I want the duplicate value (the replicate variable in the code) to be printed next to the original value. In the above desired output, since AB1012 has a duplicate, the duplicate value was printed next to the original value, which is AB1012_H1. Similarly, for AB1015.
Looping over the mapDups is giving me the following information and telling me that original position of AB1015 is 4 and duplicate is found at 5th position. Similary, original position of AB1012 is 1 and duplicate is found at 6th position. I was thinking of using two array lists to store firstPositionofOriginalCase and duplicatePositionofOriginalCase but I'm not sure if this is the right way to go about this problem.

AB1015|[4, 5]
AB1011|[0]
AB1012|[1, 6]
AB1013|[2]
AB1014|[3]

Hence, wanted to ask if anyone can think of better way of handling above situation such that I can get what I'm looking for.