How do I sort items of an ArrayList?

By I Wayan Saryada in Core API, Util Package 0 Comment

This example shows you how we can sort items of an ArrayList using the Collections.sort() method. Beside accepting the list object to be sorted we can also pass a Comparator implementation to define the sorting behaviour such as sorting in descending or ascending order.

package org.kodejava.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class ArrayListSortExample {
    public static void main(String[] args) {
        /*
         * Create a collections of colours
         */
        List<String> colours = new ArrayList<>();
        colours.add("red");
        colours.add("green");
        colours.add("blue");
        colours.add("yellow");
        colours.add("cyan");
        colours.add("white");
        colours.add("black");

        /*
         * We can sort items of a list using the Collections.sort() method.
         * We can also reverse the order of the sorting by passing the
         * Collections.reverseOrder() comparator.
         */
        Collections.sort(colours);
        System.out.println(Arrays.toString(colours.toArray()));

        colours.sort(Collections.reverseOrder());
        System.out.println(Arrays.toString(colours.toArray()));
    }
}

The code will output:

[black, blue, cyan, green, red, white, yellow]
[yellow, white, red, green, cyan, blue, black]

How do I sort array values in case-insensitive order?

By I Wayan Saryada in Core API, Util Package 1 Comment

By default, when sorting an arrays the value will be ordered in case-sensitive order. This example show you how to order it in case-insensitive order.

package org.kodejava.util;

import java.util.Arrays;

public class SortArrayCaseSensitivity {
    public static void main(String[] args) {
        String[] teams = new String[5];
        teams[0] = "Manchester United";
        teams[1] = "chelsea";
        teams[2] = "Arsenal";
        teams[3] = "liverpool";
        teams[4] = "EVERTON";

        // Sort array, by default it will be sorted in case-sensitive order.
        // [Arsenal, EVERTON, Manchester United, chelsea, liverpool]
        Arrays.sort(teams);
        System.out.println("Case sensitive  : " + Arrays.toString(teams));

        // Sort array in case-insensitive order
        // [Arsenal, chelsea, EVERTON, liverpool, Manchester United]
        Arrays.sort(teams, String.CASE_INSENSITIVE_ORDER);
        System.out.println("Case insensitive: " + Arrays.toString(teams));
    }
}

The result of the code snippet above:

Case sensitive  : [Arsenal, EVERTON, Manchester United, chelsea, liverpool]
Case insensitive: [Arsenal, chelsea, EVERTON, liverpool, Manchester United]

How do I sort array values in descending order?

By I Wayan Saryada in Core API, Util Package 0 Comment

Here you will find an example on how to sort the values of an array in ascending or descending order.

package org.kodejava.util;

import java.util.Arrays;
import java.util.Collections;

public class SortArrayWithOrder {
    public static void main(String[] args) {
        Integer[] points = new Integer[5];
        points[0] = 94;
        points[1] = 53;
        points[2] = 70;
        points[3] = 44;
        points[4] = 64;
        System.out.println("Original  : " + Arrays.toString(points));

        // Sort the points array, the default order is in ascending order.
        // [44, 53, 64, 70, 94]
        Arrays.sort(points);
        System.out.println("Ascending : " + Arrays.toString(points));

        // Sort the points array in descending order.
        // [94, 70, 64, 53, 44]
        Arrays.sort(points, Collections.reverseOrder());
        System.out.println("Descending: " + Arrays.toString(points));
    }
}

The result of the code snippet above are:

Original  : [94, 53, 70, 44, 64]
Ascending : [44, 53, 64, 70, 94]
Descending: [94, 70, 64, 53, 44]

How do I store properties as XML file?

By I Wayan Saryada in Core API, IO 0 Comment

In the previous example, How do I load properties from XML file? we read properties from XML file. Now it’s the turn on how to store the properties as XML file.

package org.kodejava.io;

import java.io.FileOutputStream;
import java.nio.charset.StandardCharsets;
import java.util.Properties;

public class PropertiesToXml {
    public static void main(String[] args) throws Exception {
        Properties properties = new Properties();
        properties.setProperty("db.type", "mysql");
        properties.setProperty("db.url", "jdbc:mysql://localhost:3306/kodejava");
        properties.setProperty("db.username", "root");
        properties.setProperty("db.password", "");

        FileOutputStream fos = new FileOutputStream("db-config.xml");
        properties.storeToXML(fos, "Database Configuration", StandardCharsets.UTF_8);
    }
}

The saved XML file will look like the properties file below:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
    <comment>Database Configuration</comment>
    <entry key="db.type">mysql</entry>
    <entry key="db.password"></entry>
    <entry key="db.username">root</entry>
    <entry key="db.url">jdbc:mysql://localhost:3306/kodejava</entry>
</properties>

How do I load properties from XML file?

By I Wayan Saryada in Core API, Util Package 0 Comment

Reading XML properties can be easily done using the java.util.Properties.loadFromXML() method. Just like reading the properties from a file that contains a key=value pairs, the XML file will also contain a key and value wrapped in the following XML format.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
    <comment>Application Configuration</comment>
    <entry key="data.folder">D:\AppData</entry>
    <entry key="jdbc.url">jdbc:mysql://localhost/kodejava</entry>
</properties>

package org.kodejava.util;

import java.util.Properties;

public class LoadXmlProperties {
    public static void main(String[] args) {
        LoadXmlProperties demo = new LoadXmlProperties();
        try {
            Properties properties = demo.readProperties();

            //Display all properties information
            properties.list(System.out);

            // Read the value of data.folder and jdbc.url configuration
            String dataFolder = properties.getProperty("data.folder");
            System.out.println("data.folder = " + dataFolder);
            String jdbcUrl = properties.getProperty("jdbc.url");
            System.out.println("jdbc.url    = " + jdbcUrl);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private Properties readProperties() throws Exception {
        Properties properties = new Properties();
        properties.loadFromXML(getClass().getResourceAsStream("/configuration.xml"));
        return properties;
    }
}

The result of the code snippet above:

-- listing properties --
data.folder=D:\AppData
jdbc.url=jdbc:mysql://localhost/kodejava
data.folder = D:\AppData
jdbc.url    = jdbc:mysql://localhost/kodejava