Java Collection Interface用法及代碼示例

// Java program to illustrate Collection interface
import java.io.*;
import java.util.*;
public class CollectionDemo {
    public static void main(String args[])
    {
        // creating an empty LinkedList
        Collection<String> list = new LinkedList<String>();
        // use add() method to add elements in the list
        list.add("Geeks");
        list.add("for");
        list.add("Geeks");
        // Output the present list
        System.out.println("The list is: " + list);
        // Adding new elements to the end
        list.add("Last");
        list.add("Element");
        // printing the new list
        System.out.println("The new List is: " + list);
    }
}

// Java code to illustrate adding
// elements to the Collection
import java.io.*;
import java.util.*;
public class AddingElementsExample {
    public static void main(String[] args)
    {
        // create an empty array list with an initial
        // capacity
        Collection<Integer> list1 = new ArrayList<Integer>(5);
        // use add() method to add elements in the list
        list1.add(15);
        list1.add(20);
        list1.add(25);
        // prints all the elements available in list
        for (Integer number : list1) {
            System.out.println("Number = " + number);
        }
        // Creating an empty ArrayList
        Collection<Integer> list2 = new ArrayList<Integer>();
        // Appending the collection to the list
        list2.addAll(list1);
        // displaying the modified ArrayList
        System.out.println("The new ArrayList is: " + list2);
    }
}

// Java program to demonstrate removing
// elements from a Collection
import java.util.*;
public class RemoveElementsExample {
    public static void main(String[] argv) throws Exception
    {
        // Creating object of HashSet<Integer>
        Collection<Integer> set1 = new HashSet<Integer>();
        // Populating arrset1
        set1.add(1);
        set1.add(2);
        set1.add(3);
        set1.add(4);
        set1.add(5);
        // print set1
        System.out.println("Initial set1 : " + set1);
         
          // remove a particular element
          set1.remove(4);
       
          // print modified set1
        System.out.println("set1 after removing 4 : " + set1);
       
        // Creating another object of HashSet<Integer>
        Collection<Integer> set2 = new HashSet<Integer>();
        set2.add(1);
        set2.add(2);
        set2.add(3);
        // print set2
        System.out.println("Collection Elements to be removed : " + set2);
        // Removing elements from set1
        // specified in set2
        // using removeAll() method
        set1.removeAll(set2);
        // print arrset1
        System.out.println("set 1 after removeAll() operation : " + set1);
    }
}

// Java code to illustrate iterating
// over a Collection
import java.util.*;
public class IteratingExample {
    public static void main(String[] args)
    {
        // Create and populate the list
        Collection<String> list = new LinkedList<>();
        list.add("Geeks");
        list.add("for");
        list.add("Geeks");
        list.add("is");
        list.add("a");
        list.add("CS");
        list.add("Students");
        list.add("Portal");
        // Displaying the list
        System.out.println("The list is: " + list);
        // Create an iterator for the list
        // using iterator() method
        Iterator<String> iter = list.iterator();
        // Displaying the values after iterating
        // through the list
        System.out.println("\nThe iterator values" + " of list are: ");
        while (iter.hasNext()) {
            System.out.print(iter.next() + " ");
        }
    }
}