Introduction to Java Vector Class
Vector is a class in Java that implements a dynamic array of objects. That is, the array can be expanded or shrinked based on the requirement. It is mostly useful in the cases where array size is not known in advance. Unlike arrays, vector is synchronized and contain a lot of legacy methods that collection frameworks do not have. It is inherited from the package java.util and implements the interface List. It is suggested to use this class in the case of thread-safe implementation. Otherwise, it is better to use ArrayList.
Declaration:
Below is the declaration of vector class in Java:
public class Vector<E> extends Object<E> implements List<E>,Cloneable, SerializableConstructors of Java Vector Class
Given below are the constructors of Java Vector Class:
- Vector(): An empty vector gets constructed with size of internal data array as ten and standard capacity increment as 0.
- Vector(Collection<? extends E> c): A vector gets constructed with elements in the mentioned collection and ordered based on the collection’s iterator.
- Vector(int c): An empty vector gets constructed with initial Capacity c and capacity increment as 0.
- Vector(int c, intcapacityIncrement): An empty vector gets constructed with initial Capacity c and capacity increment.
Methods of Java Vector Class
Given below are the methods of Java Vector Class:
- add(E e): Element e appends to the vector end.
- add(int index, E element): Element e will be inserted to the position mentioned in the vector.
- addAll(Collection<? extends E> c): All elements append to the vector end and ordered based on the collection’s iterator.
- add(int index, E element): All elements in the collection mentioned will be inserted to the position mentioned in the vector.
- addElement(E obj): Mentioned component will be added to the end of the vector, with size incrementing by one.
- capacity(): Current capacity will be returned for the vector.
- clear(): All the elements will be removed from the vector.
- clone(): Clone will be returned for the vector.
- contains(Object o): If the vector consists of the element mentioned, true will be returned.
- containsAll(Collection<?> c): If the vector consists of all the elements mentioned in the collection mentioned, true will be returned.
- copyInto(Object[] anArray): Components of this vector is copied in to the array mentioned.
- elementAt(int index): Components at the mentioned index will be returned.
- elements(): Enumeration of the components will be returned for this vector.
- ensureCapacity(int minCapacity): Vector capacity gets increased and ensures that vector can hold number of components mentioned by minimum argument capacity.
- equals(Object o): For equality, specified object will be compared with the vector.
- firstElement(): First item, at index 0 for the vector will be returned.
- get(int index): Element at the mentioned position will be returned in this Vector.
- hashCode(): Value of hashcode will be returned for this Vector.
- indexOf(Object o): Index will be returned for the 1st occurrence of an item in the Vector. If that item is not present, -1 will be returned.
- indexOf(Object o, int index): Index will be returned for the 1st occurrence of the mentioned item in the Vector. If that item is not present, -1 will be returned.
- insertElementAt(E obj, int index): Object mentioned will be inserted as a component in the vector to the index mentioned.
- isEmpty(): Checks whether the vector has components or not.
- iterator(): Iterator will be returned over the items in the list in correct sequence.
- lastElement(): Last component will be returned for the vector.
- lastIndexOf(Object o): Index will be returned for the final occurrence of an item in the Vector. If that item is not present, -1 will be returned.
- lastIndexOf(Object o, int index): Index will be returned for the final occurrence of mentioned item in the Vector. If that item is not present, -1 will be returned.
- listIterator(): A list iterator will be returned over the list items.
- listIterator(int index): A list iterator will be returned over the list items where starting is the mentioned position.
- remove(int index): Element at the mentioned position will be removed from this Vector.
- remove(Object o): 1st occurrence of an item will be removed from the Vector. If that item is not present, it remains unchanged.
- removeAll(Collection<?> c): All elements that are available in the collection will be removed from the Vector.
- removeAllElements(): All elements will be removed from the Vector and size becomes 0.
- retainAll(Collection<?> c): All elements that are available in the collection will be retained from the Vector.
- set(int index, E element): Element at the mentioned position will be replaced in this Vector with the element mentioned.
- setElementAt(E obj, int index): Component at the mentioned index will be set to the given object.
- setSize(int newSize): Vector size will be set.
- size(): Count of components will be returned.
- subList(int fromIndex, int toIndex): A view will be returned for the portion between fromIndex(inclusive) and toIndex(exclusive).
- toArray(): Gets an array that contains all elements in the vector in right order.
- toString(): String representation will be returned for the vector.
- trimToSize(): Vector capacity is trimmed to current size of vector.
Examples
Given below are the examples mentioned:
Example #1
Code:
import java.util.Vector;
public class Main {
public static void main(String arg[]) {
Vector<String>vctr = new Vector<>(2);
vctr.add("1");
vctr.add(1,"2");
System.out.println("Vector 0: " + vctr);
Vector<String> vctr1 = new Vector<>();
vctr1.add("8");
vctr1.addAll(vctr);
System.out.println("Vector 1: " + vctr1);
System.out.println("Capacity: "+vctr1.capacity());
System.out.println("Cloned vector: "+vctr1.clone());
System.out.println("Existence of 2: "+vctr1.contains("2"));
System.out.println("Item at 1 is = "+vctr1.elementAt(1));
System.out.println("vector0 equals vector2? "+vctr.equals(vctr1));
System.out.println("Element 1 is = "+vctr1.firstElement());
vctr1.forEach(System.out::println);
System.out.println("HashCode = "+vctr1.hashCode());
vctr1.remove(1);
System.out.println("After removing element 1: " + vctr1);
vctr1.clear();
System.out.println("After clear(): " + vctr1);
} }Output:
Example#2
Code:
import java.util.ListIterator;
import java.util.Vector;
public class Main {
public static void main(String arg[]) {
Vector<Integer>vctr = new Vector<>(2);
vctr.add(3);
vctr.add(1,2);
vctr.setElementAt(2, 1);
System.out.println("Vector 0: " + vctr);
vctr.setSize(6);
System.out.println("Components after new size: ");
for (Integer n :vctr) {
System.out.println("Numbers: " +n);
}
ListIterator<Integer> li = vctr.listIterator();
System.out.println("Elements are: ");
while(li.hasNext())
{
System.out.println(li.next());
}
}
}Output:
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This is a guide to Java Vector Class. Here we discuss the introduction to Java Vector Class, constructors, methods with programming examples. You may also have a look at the following articles to learn more –
