I have an Arraylist with the values:
was - 2
it - 2
the - 2
times - 2
of - 2
best - 1
worst - 1
This list has just been sorted by the count value at the end of the string(using selection sort), but now I want to sort the words that have the same count alphabetically and I have no idea how to do this.
So the expected output should be
[it - 2, of - 2, the - 2, times - 2, was - 2, best - 1, worst - 1]
For sorting there are always two approaches:
ComparableComparatorI'll assume your values are some sort of class like
public class Entry {
private final String text;
private final int count;
// getters, constructor, toString, ...
}
For the first option, simply let your class implement Comparable with a logic that first uses the count and then, if it is equal, considers the text.
public class Entry implements Comparable<? extends Entry> {
private final String text;
private final int count;
// getters, constructor, toString, ...
@Override
public int compareTo(Entry other) {
int countResult = -1 * Integer.compare(count, other.count);
return countResult != 0 ? countResult : text.compareTo(other.text);
}
}
Then simply sort your collection:
Collections.sort(entries);
The -1 * is to get the sorting-by-count descending instead of the default, ascending.
You can do the very same using a Comparator. Fortunately, we got some nice helper methods since Java 8 that make this even simpler, here is the code:
Comparator<Entry> comparator = Comparator.comparingInt(Foo::getValue)
.reversed()
.thenComparing(Foo::getText);
And then you just give that to the sorter:
entries.sort(comparator);
Split the strings on \s+-\s+ which means one or more whitespace characters (i.e. \s+) followed by - which in turn is followed by one or more whitespace characters.
Perform the first level of comparison for the descending order of the numeric (second) parts and then perform the second level of comparison for the ascending order of the first parts.
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
public class Main {
public static void main(String args[]) {
List<String> list = new ArrayList<>(
List.of("was - 2", "it - 2", "the - 2", "times - 2", "of - 2", "best - 1", "worst - 1"));
list.sort(new Comparator<String>() {
@Override
public int compare(String s1, String s2) {
String[] s1Parts = s1.split("\\s+-\\s+");
String[] s2Parts = s2.split("\\s+-\\s+");
int i = Integer.compare(Integer.parseInt(s2Parts[1]), Integer.parseInt(s1Parts[1]));
if (i != 0) {
return i;
}
return s1Parts[0].compareTo(s2Parts[0]);
}
});
System.out.println(list);
}
}
Output:
[it - 2, of - 2, the - 2, times - 2, was - 2, best - 1, worst - 1]
Note: if the two parts of each string are always separated by -, you can split as s1.split(" - ");.
compare method of Comparator. There you write how two given objects need to be compared. You can learn more about it from this link. You can also check this and this. Feel free to comment in case of any further doubt.1:- With Use Comparator
Collections.sort(creatorIdList, (Object o1,Object o2)->{
//return 0;
});
