Removing duplicates while sorting numbers inside a String in java

Question

I need to sort strings containing numbers

Eg :

 input : {"1","12","12","2","ABC","a"}

 Expected output: 1 2 12 a ABC

 My output  :1 2 12 12 a ABC 

I am not able to remove duplicate. can anyone help me with this ?

Below is the code I used for sorting

public static String[] Sort(String[] list) {
    Comparator<String> comp = new Comparator<String>() {
        public int compare(String str1, String str2) {
            try {
                int num1 = Integer.parseInt(str1);
                int num2 = Integer.parseInt(str2);
                return Integer.compare(num1, num2);
            }
            catch (NumberFormatException e) {
                return str1.compareTo(str2);
            }
        }
    };
    Arrays.sort(list, comp);
    return list;
}

Thanks in Advance

Answer 1

The easiest way of approaching this problem is using Streams . This would let us tackle this problem using a single line of code.

String[] sorted = Arrays.stream(list).distinct().sorted((s1,s2)->compare(s1,s2)).toArray(String[]::new);

edit: added use of the given comparator for full support of both number strings and other strings.

Also, the comparator should compare the strings after toLowerCase() have been applied. Resulting in

catch (NumberFormatException e) {
            return str1.toLowerCase().compareTo(str2.toLowerCase());
}

Answer 2

Set can be used to remove dublicates

public static Set<String> sort(String[] list) {
    Comparator<String> comp = new Comparator<String>() {
        public int compare(String str1, String str2) {
            try {
                int num1 = Integer.parseInt(str1);
                int num2 = Integer.parseInt(str2);
                return Integer.compare(num1, num2);
            }
            catch (NumberFormatException e) {
                return str1.compareTo(str2);
            }
        }
    };
    Set<String> set = new TreeSet<String>(comp);
    set.addAll(Arrays.asList(list));
    System.out.println(set);
    return set;
}

Answer 3

You want to sort as well remove duplicate. it means its two process that is difficult for comparator to do both, you need to get distinct string in array, so sort and then get only distinct, there are lot of ways, but i did which is easy to understand:

public static String[] Sort(String[] list) {
        Comparator<String> comp = new Comparator<String>() {
            public int compare(String str1, String str2) {
                try {
                    int num1 = Integer.parseInt(str1);
                    int num2 = Integer.parseInt(str2);
                    return Integer.compare(num1, num2);
                }
                catch (NumberFormatException e) {
                    return str1.compareTo(str2);
                }
            }
        };
        Arrays.sort(list, comp);
        ArrayList<String> new_list = new ArrayList<String>;
        if(list.length()>0){ 
          new_list.add(list[0]);
        }
        for(String s : list){
         //comparing with the last added string in list, if not same then add
          if(!new_list.get(new_list.size()-1).equals(s)){
             new_list.add(s);
           }
        }
        return new_list.toArray(new String[new_list.size()]);
    }

Answer 4

Try this. I included a more complicated array of the same elements to verify.

String[] vals = {"1","ABC","12","a", "1", "2", "12","2","ABC", "a", "ABC","a"};


Comparator<String> comp = ((a,b)-> {
   if (a.matches("\\d+") && b.matches("\\d+")) {
       return Integer.compare(Integer.valueOf(a), Integer.valueOf(b));
   } else {
            return a.toLowerCase().compareTo(b.toLowerCase());
   }
});

String[] result = Arrays.stream(vals).distinct().sorted(comp).toArray(String[]::new);
            
System.out.println(Arrays.toString(result));

Prints

[1, 2, 12, a, ABC]

Answer 5

You've asked 2 differents question ! To answear to the first:

Comparator<String> comparator = new Comparator<String>() {
        
        public int compare(String str1, String str2) {
            return isInteger(str1) && isInteger(str2)
                   ? Integer.compare(num1, num2)
                   : isInteger(str1) 
                   ? -1
                   : isInteger(str2)
                   ? 1
                   : str1.compareTo(str2);
        }
    };

private boolean isInteger(String value) {
    try {
        Integer.parseInt(value);
        return true;
    }
    catch (NumberFormatException e) {
        return false;
    }