JAVA: Preventing Duplicate Entries to an ArrayList

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I am trying to prevent duplicate entries from being added to an ArrayList as the list is being populated whilst reading through each line of a file. Each line of the file is in the format "node1 node2" (tab delimiter). A duplicate here could either be "node1 node2" or "node2 node1". Here is my code to try and perform this operation:

while((line = bufferedReader.readLine()) != null) {

     String delimiter = "\t";
     String[] tempnodelist;  
     tempnodelist = line.split(delimiter);

     for (int i=0; i <= edgesnumber; i++) {   //edgesnumber = edges.size()

         if (tempnodelist[0] && tempnodelist[1] != edges.get(i)) {

             edges.add(line);

            }
        }

     nodes.add(tempnodelist[0]);  
     nodes.add(tempnodelist[1]); //intial intended use of tempnodelist.

}

Since I'm already splitting each line to make a HashSet of each node, I'm trying to use this to check for duplicates. At the moment I just can't seem to get the syntax right. How can I check through previous entries of the ArrayList for duplicates, and prevent them from being added, whist continuing to populate the ArrayList? what is wrong with this code currently?

Please ask any questions if anything is unclear,

Thanks in advance!

arraylist java
6 Answers
ArrayList<String> ar=new ArrayList<String>();
String a[]={"cat","bat","cat","knife"};
for(int i=0;i<a.length;i++){
    if(!ar.contains(a[i])){
        ar.add(a[i]);
    }
}

Create an array list, and check whether it contains the string to be inserted. If it does not contain the string, then you can add it into the array list. This way you can avoid the duplicate entries in the array list.

The elements in the array list for the above code would be

cat bat knife

user_80595980
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