How to get a sublist of an exist list by index in Java ?
package org.4spaces;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
public class SplitList {
/**
* naive
*
* @param originList
* @param fromIndex inclusive
* @param toIndex exclusive
* @return sublist
*/
public List naiveSplit(List originList, int fromIndex, int toIndex) {
List subList = new ArrayList();
if (fromIndex >= 0 && toIndex <= originList.size()) {
for (int i = 0; i < originList.size(); i++) {
if (i >= fromIndex && i < toIndex) {
subList.add(originList.get(i));
}
}
}
return subList;
}
/**
* Java List.subList
*
* @param originList
* @param fromIndex inclusive
* @param toIndex exclusive
* @return sublist
*/
public List subListSplit(List originList, int fromIndex, int toIndex) {
return originList.subList(fromIndex, toIndex);
}
/**
* Java 8 Collectors.partitioningBy
*
* @param originList
* @param fromIndex inclusive
* @param toIndex exclusive
* @return sublist
*/
public List partitioningBySplit(List originList, int fromIndex, int toIndex) {
Map<Boolean, List> subList = (Map<Boolean, List>) originList.stream().collect(Collectors.partitioningBy(s -> originList.indexOf(s) >= fromIndex && originList.indexOf(s) < toIndex));
return subList.get(true);
}
/**
* Java 8 Collectors.groupingBy
*
* @param originList
* @param fromIndex inclusive
* @param toIndex exclusive
* @return sublist
*/
public List groupingBySplit(List originList, int fromIndex, int toIndex) {
Map<Boolean, List> subList = (Map<Boolean, List>) originList.stream().collect(Collectors.groupingBy(s -> originList.indexOf(s) >= fromIndex && originList.indexOf(s) < toIndex));
return subList.get(true);
}
}
Reference: