Difference between Vector and ArrayList in Java, vectorarraylist

Difference between Vector and ArrayList in Java, vectorarraylist

First, we can see that both of these classes implement the List interface, and the List interface has three implementation classes: ArrayList, Vector, and sorted List. List is used to store multiple elements, maintain the order of elements, and allow repeated elements. The differences between the three implementation classes are as follows:

Check the Java source code and find that when the array size is not enough, you need to re-create the array and copy the elements to the new array. The size of the extended array of ArrayList and Vector is different.

 

In ArrayList:

1 public boolean add (E e) {2 3 ensureCapacity (size + 1); // add elements to determine whether they can be accommodated. If not, create an array 4 5 elementData [size ++] = e; 6 7 return true; 8 9} 10 11 public void ensureCapacity (int minCapacity) {12 13 modCount ++; 14 15 int oldCapacity = elementData. length; 16 17 if (minCapacity> oldCapacity) {18 19 Object oldData [] = elementData; // This row is useless, I don't know why the developer considers 20 21 int newCapacity = (oldCapacity * 3)/2 + 1; // increase the size of the new array 22 23 if (newCapacity <minCapacity) 24 25 newCapacity = minCapacity; 26 27 // minCapacity is usually close to size, so this is a win: 28 29 elementData = Arrays. copyOf (elementData, newCapacity); 30 31} 32 33} 34 35

 

 

Vector:

 1 private void ensureCapacityHelper(int minCapacity) { 2  3     int oldCapacity = elementData.length; 4  5     if (minCapacity > oldCapacity) { 6  7         Object[] oldData = elementData; 8  9         int newCapacity = (capacityIncrement > 0) ?10 11        (oldCapacity + capacityIncrement) : (oldCapacity * 2);12 13         if (newCapacity < minCapacity) {14 15        newCapacity = minCapacity;16 17         }18 19          elementData = Arrays.copyOf(elementData, newCapacity);20 21     }22 23 }24 25 

 

The differences between ArrayList and Vector are as follows: