How to sort strings such that values with extra information appear first?

arrays, java, sorting

Solution

Use a comparator

    import java.util.Comparator;
    class CustomComparator implements Comparator<String> {
        @Override
        public int compare(String a, String b) {
            if(a.contains("-") && !b.contains("-"))
                 return 1;
            else if(!a.contains("-") && b.contains("-"))
                 return -1;
            return a.compareTo(b);
        }
    }
    Collections.sort(arrays, new CustomComparator());

return a negative value means b comes before a and a positive value means a comes before b

Problem

I am trying to sort the following strings ``` 1.0.0.0-00000000-00000 2.1.0.0 2.2.0.0 2.3.0.0-00000000-00000 ``` I currently have these values in an array of strings. ``` String[] arrays = {"1.0.0.0-00000000-00000", "2.1.0.0", "2.2.0.0", "2.3.0.0-00000000-00000"}; ``` I am trying to have an output where if there is no "-" then those values go to the end of my array in a sorted order. I am trying to have an output as follows: ``` 1.0.0.0-00000000-00000 2.3.0.0-00000000-00000 2.1.0.0 2.2.0.0 ``` I have tried `Arrays.sort(arrays)` but I am not sure as to how to go about sorting this? ``` import java.util.Arrays; import java.util.Comparator; import java.util.Collections; public class HelloWorld{ public static void main(String []args){ String[] arrays = {"1.0.0.0-00000000-00000", "2.1.0.0", "2.2.0.0", "2.3.0.0-00000000-00000"}; String[] newArray = new String[arrays.length]; class CustomComparator implements Comparator<String> { @Override public int compare(String a, String b) { if(a.contains("-") && !b.contains("-")) return 1; else if(!a.contains("-") && b.contains("-")) return -1; return a.compareTo(b); } } Arrays.sort(arrays, new CustomComparator()); for(String array : arrays) { System.out.println(array); } } } Error: $javac HelloWorld.java 2>&1 HelloWorld.java:25: error: no suitable method found for sort(String[],CustomComparator) Collections.sort(arrays, new CustomComparator()); ^ method Collections.<T#1>sort(List<T#1>,Comparator<? super T#1>) is not applicable (no instance(s) of type variable(s) T#1 exist so that argument type String[] conforms to formal parameter type List<T#1>) method Collections.<T#2>sort(List<T#2>) is not applicable (cannot instantiate from arguments because actual and formal argument lists differ in length) where T#1,T#2 are type-variables: T#1 extends Object declared in method <T#1>sort(List<T#1>,Comparator<? super T#1>) T#2 extends Comparable<? super T#2> declared in method <T#2>sort(List<T#2>) 1 error The method gave me an output of 2.1.0.0 2.2.0.0 1.0.0.0-00000000-00000 2.3.0.0-00000000-00000 as opposed to 1.0.0.0-00000000-00000 2.3.0.0-00000000-00000 2.1.0.0 2.2.0.0 ```

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