點選檢視程式碼
import lombok.Getter;
import java.util.*;
import java.util.stream.Collectors;
public class CollectionUtils {
/**
* compare
* @param newCollection 新集合
* @param oldCollection 舊集合
* @param comparator
* @param <T>
* @return
*/
public static <T> CompareResult<T> compare(List<T> newCollection, List<T> oldCollection, Comparator<T> comparator) {
List<T> existNewElements = new ArrayList<>();
List<T> existOldElements = new ArrayList<>();
Iterator<T> newIterator = newCollection.iterator();
while (newIterator.hasNext()) {
T newObj = newIterator.next();
Iterator<T> oldIterator = oldCollection.iterator();
while (oldIterator.hasNext()) {
T oldObj = oldIterator.next();
if (comparator.compare(newObj, oldObj) == 0) {
existNewElements.add(newObj);
existOldElements.add(oldObj);
try {
oldIterator.remove();
newIterator.remove();
} catch (UnsupportedOperationException e) {
throw new RuntimeException("");
}
}
}
}
return new CompareResult<T>(newCollection, oldCollection, existNewElements, existOldElements);
}
@Getter
public static class CompareResult<T> {
private final List<T> addElements;
private final List<T> deleteElements;
private final List<T> existNewElements;
private final List<T> existOldElements;
public CompareResult(List<T> addElements, List<T> delValue, List<T> existNewElements, List<T> existOldElements) {
this.addElements = addElements;
this.deleteElements = delValue;
this.existNewElements = existNewElements;
this.existOldElements = existOldElements;
}
}
public static void main(String[] args) {
List<User> newCollection = new ArrayList<>(Arrays.asList(user2_new, user3));
List<User> oldCollection = new ArrayList<>(Arrays.asList(user1, user2));
System.out.println("newCollection: " + newCollection);
System.out.println("oldCollection: " + oldCollection);
CompareResult<User> compareResult = compare(newCollection, oldCollection, (o1, o2) -> {
if (o1.getId().equals(o2.getId())) {
return 0;
} else {
return -1;
}
});
System.err.println("addElements: " + compareResult.getAddElements());
System.err.println("deleteElements: " + compareResult.getDeleteElements());
System.err.println("existNewElements: " + compareResult.getExistNewElements());
System.err.println("existOldElements: " + compareResult.getExistOldElements());
}
}