Java – how to sort strings so that values with additional information are displayed first?
•
Java
I tried to sort the following string
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 a string array
String[] arrays = {"1.0.0.0-00000000-00000","2.1.0.0","2.2.0.0","2.3.0.0-00000000-00000"};
I try to have an output. If there is no "–", the values reach the end of my array in sorted order I want to output the following:
1.0.0.0-00000000-00000 2.3.0.0-00000000-00000 2.1.0.0 2.2.0.0
I tried arrays Sort (array), but I'm not sure how to sort it?
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","2.3.0.0-00000000-00000"};
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
Solution
Use 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());
Returning a negative value means B precedes a, while a positive value means a precedes B
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