• 交換ArrayList中兩個位置的元素

public static <T> void swap(List<T> list, int oldPosition, int newPosition){
    if(null == list){
        throw new IllegalStateException("The list can not be empty...");
    }
    T tempElement = list.get(oldPosition);

    if(oldPosition < newPosition){
        
 
for(int i = oldPosition; i < newPosition; i++){
            list.set(i, list.get(i + 1));
        }
        list.set(newPosition, tempElement);
    }
    
    if(oldPosition > newPosition){
        for(int i = oldPosition; i > newPosition; i--){
            list.set(i, list.get(i - 1));
        }
        list.set(newPosition, tempElement);
    }
}
 

public static <T> void swap(List<T> list, int oldPosition, int newPosition){
    if(null == list){
        throw new IllegalStateException("The list can not be empty...");
    }

    if(oldPosition < newPosition){
        for(int i = oldPosition; i < newPosition; i++){
            Collections.swap(list, i, i 
 
+ 1);
        }
    }

    if(oldPosition > newPosition){
        for(int i = oldPosition; i > newPosition; i--){
            Collections.swap(list, i, i - 1);
        }
    }
}