How do I know if a date is after another date?

By Wayan in Core API, Util Package 0 Comment

This example demonstrate Date‘s class after() method to check if a date is later than another date.

package org.kodejava.util;

import java.util.Date;
import java.util.Calendar;

public class DateCompareAfter {
    public static void main(String[] args) {
        // Get current date
        Date today = new Date();

        // Add 1 day from the current date.
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.DATE, 1);
        Date tomorrow = calendar.getTime();

        // Tests if this date is after the specified date. This method will
        // return true if the value time represented by the tomorrow object
        // is later than today.
        if (tomorrow.after(today)) {
            System.out.println(tomorrow + " is after " + today);
        }
    }
}

The result of the code snippet above is:

Tue Oct 05 20:52:34 CST 2021 is after Mon Oct 04 20:52:33 CST 2021

How do I know if a date is before another date?

By Wayan in Core API, Util Package 0 Comment

This example demonstrate Date‘s class before() method to check if a date is earlier than another date.

package org.kodejava.util;

import java.util.Date;
import java.util.Calendar;

public class DateCompareBefore {
    public static void main(String[] args) {
        // Get current date
        Date today = new Date();

        // Subtract 1 day from the current date.
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.DATE, -1);
        Date yesterday = calendar.getTime();

        // Tests if this date is before the specified date. This method will
        // return true if the value time represented by the yesterday object
        // is earlier than today.
        if (yesterday.before(today)) {
            System.out.println(yesterday + " is before " + today);
        }
    }
}

The result of the code snippet above is:

Sun Oct 03 20:49:36 CST 2021 is before Mon Oct 04 20:49:36 CST 2021

How do I convert java.util.Set into Array?

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

import java.util.*;

public class SetToArray {
    public static void main(String[] args) {
        // Create a java.util.Set object and add some integers into the Set.
        Set<Integer> numberSet = new HashSet<>();
        numberSet.add(1);
        numberSet.add(2);
        numberSet.add(3);
        numberSet.add(5);
        numberSet.add(8);

        // Converting a java.util.Set into an array can be done by creating a
        // java.util.List object from the Set and then convert it into an array
        // by calling the toArray() method on the list object.
        List<Integer> numberList = new ArrayList<>(numberSet);
        Integer[] numbers = numberList.toArray(new Integer[0]);

        // Display the content of numbers array.
        for (int i = 0; i < numbers.length; i++) {
            Integer number = numbers[i];
            System.out.print(number + (i < numbers.length - 1 ? ", " : "\n"));
        }

        // Display the content of numbers array using the for-each loop.
        for (Integer number : numbers) {
            System.out.print(number + ", ");
        }
    }
}

How do I convert Set into List?

By Wayan in Core API, Util Package 0 Comment

The code below gives you an example of converting a java.util.Set into a java.util.List. It has simply done by creating a new instance of List and pass the Set as the argument of the constructor.

package org.kodejava.util;

import java.util.*;

public class SetToList {
    public static void main(String[] args) {
        // Create a Set and add some objects into the Set.
        Set<Object> set = new HashSet<>();
        set.add("A");
        set.add(10L);
        set.add(new Date());

        // Convert the Set to a List can be done by passing the Set instance into
        // the constructor of a List implementation class such as ArrayList.
        List<Object> list = new ArrayList<>(set);
        for (Object o : list) {
            System.out.println("Object = " + o);
        }
    }
}

The output of the code snippet are:

Object = A
Object = 10
Object = Mon Oct 04 20:20:26 CST 2021

How do I convert Properties into Map?

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

import java.util.Properties;
import java.util.Map;
import java.util.HashMap;
import java.util.Set;

public class PropertiesToMap {
    public static void main(String[] args) {
        // Create a new instance of Properties.
        Properties properties = new Properties();

        // Populate properties with a dummy application information
        properties.setProperty("app.name", "HTML Designer");
        properties.setProperty("app.version", "1.0");
        properties.setProperty("app.vendor", "HTML Designer Inc");

        // Create a new HashMap and pass an instance of Properties. Properties
        // is an implementation of a Map which keys and values stored as in a
        // String.
        Map<Object, Object> map = new HashMap<>(properties);

        // Get the entry set of the Map and print it out.
        Set<Map.Entry<Object, Object>> propertySet = map.entrySet();
        for (Map.Entry<Object, Object> entry : propertySet) {
            System.out.printf("%s = %s%n", entry.getKey(), entry.getValue());
        }
    }
}

The output of the code snippet above:

app.vendor = HTML Designer Inc
app.name = HTML Designer
app.version = 1.0