How do I iterate LinkedList elements using ListIterator?

By Wayan in Core API, Util Package 0 Comment

This example show you how to use the ListIterator interface to iterate elements of a LinkedList.

package org.kodejava.util;

import java.util.List;
import java.util.LinkedList;
import java.util.ListIterator;

public class LinkedListListIterator {
    public static void main(String[] args) {
        List<String> grades = new LinkedList<>();
        grades.add("A");
        grades.add("B");
        grades.add("C");
        grades.add("D");
        grades.add("E");

        // Retrieves object from LinkedList using the ListIterator
        // interface.
        ListIterator<String> iterator = grades.listIterator();
        while (iterator.hasNext()) {
            System.out.println("Grades: " + iterator.next());
            System.out.println("  hasPrevious  : " + iterator.hasPrevious());
            System.out.println("  hasNext      : " + iterator.hasNext());
            System.out.println("  previousIndex: " + iterator.previousIndex());
            System.out.println("  nextIndex    : " + iterator.nextIndex());
        }
    }
}

The program will print the following output:

Grades: A
  hasPrevious  : true
  hasNext      : true
  previousIndex: 0
  nextIndex    : 1
Grades: B
  hasPrevious  : true
  hasNext      : true
  previousIndex: 1
  nextIndex    : 2
Grades: C
  hasPrevious  : true
  hasNext      : true
  previousIndex: 2
  nextIndex    : 3
Grades: D
  hasPrevious  : true
  hasNext      : true
  previousIndex: 3
  nextIndex    : 4
Grades: E
  hasPrevious  : true
  hasNext      : false
  previousIndex: 4
  nextIndex    : 5

How do I iterate LinkedList elements using Iterator?

By Wayan in Core API, Util Package 0 Comment

This example show you how to use the Iterator interface to iterate elements of a LinkedList.

package org.kodejava.util;

import java.util.List;
import java.util.LinkedList;
import java.util.Iterator;

public class LinkedListIterator {
    public static void main(String[] args) {
        List<String> grades = new LinkedList<>();
        grades.add("A");
        grades.add("B");
        grades.add("C");
        grades.add("D");
        grades.add("E");

        // Iterates elements in LinkedList using Iterator.
        Iterator<String> iterator = grades.iterator();
        while (iterator.hasNext()) {
            System.out.println("Grade: " + iterator.next());
        }
    }
}

This program prints the following output:

Grade: A
Grade: B
Grade: C
Grade: D
Grade: E

How do I create a LinkedList?

By Wayan in Core API, Util Package 0 Comment

A linked list is a fundamental data structure in programming. It can store data and a references to the next and/or to the previous node. There can be a singly linked list, a doubly linked list and a circularly linked list.

The code below show you how to use the java.util.LinkedList class to create a linked list. In the example we create a LinkedList to store a string object using the add(Object o) method. After create the list we iterate the list and print out the contents.

package org.kodejava.util;

import java.util.List;
import java.util.LinkedList;

public class LinkedListCreate {
    public static void main(String[] args) {
        // Creates a new instance of java.util.LinkedList and
        // adds five string object into the list.
        List<String> grades = new LinkedList<>();
        grades.add("A");
        grades.add("B");
        grades.add("C");
        grades.add("E");
        grades.add("F");

        // Iterates the LinkedList object using the for each
        // statement.
        for (String grade : grades) {
            System.out.println("Grade: " + grade);
        }
    }
}

This program will produce the following output:

Grade: A
Grade: B
Grade: C
Grade: E
Grade: F

How do I count number of weekday between two dates?

By Wayan in Core API, Util Package 0 Comment

The code below helps you find the number of a specified weekday (Monday, Tuesday, Wednesday, etc.) between two dates. The solution we used below is to loop between the two dates and check if the weekday of those dates are equals to the day we want to count.

package org.kodejava.util;

import java.util.Calendar;

public class DaysBetweenDate {
    public static void main(String[] args) {
        Calendar start = Calendar.getInstance();
        start.set(2021, Calendar.OCTOBER, 1);
        Calendar end = Calendar.getInstance();
        end.set(2021, Calendar.OCTOBER, 31);

        System.out.print("Number Monday between " +
                start.getTime() + " and " + end.getTime() + " are: ");

        int numberOfDays = 0;
        while (start.before(end)) {
            if (start.get(Calendar.DAY_OF_WEEK) == Calendar.MONDAY) {
                numberOfDays++;
                start.add(Calendar.DATE, 7);
            } else {
                start.add(Calendar.DATE, 1);
            }
        }

        System.out.println(numberOfDays);
    }
}

The result of our program is:

Number Monday between Fri Oct 01 07:55:06 CST 2021 and Sun Oct 31 07:55:06 CST 2021 are: 4

How do I get the last element of SortedSet?

By Wayan in Core API, Util Package 0 Comment 
package org.kodejava.util;

import java.util.SortedSet;
import java.util.TreeSet;

public class LastSetElement {
    public static void main(String[] args) {
        SortedSet<String> numbers = new TreeSet<>();
        numbers.add("One");
        numbers.add("Two");
        numbers.add("Three");
        numbers.add("Four");
        numbers.add("Five");

        // SortedSet orders the items it contains. We can get the last
        // item from the set using the last() method. The last item 
        // will be "Two".
        String lastElement = numbers.last();
        System.out.println("lastElement = " + lastElement);
    }
}