JAVA EE: Java Tutorial: Properties class in java [How to get the default value if the key is not present]

Tuesday 28 February 2017

Java Tutorial: Properties class in java [How to get the default value if the key is not present]

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db.properties

Java Tutorial: Properties class in java [How to get the default value if the key is not present]

PropertiesDemo.java

import java.io.FileReader;
import java.io.IOException;
import java.util.Properties;

/*
 * public String getProperty(String key, String
 *                                      defaultValue)
 * 
 * Parameters: 
 * ----------
 * 
 * key - the hashtable key. 
 * 
 * defaultValue - a default value.
 * 
 * Returns: 
 * -------
 * 
 * the value in this property list with the specified
 * key value.
 */

class PropertiesDemo
{

    public static void main(String[] args) throws IOException
    {
        FileReader fileReader = null;
        try
        {
            fileReader = new FileReader("db.properties");

            Properties p = new Properties();
            /*
             * Reads a property list (key and element pairs)
             * from the input character stream in a simple
             * line-oriented format.
             */
            p.load(fileReader);

            /*
             * Searches for the property with the specified
             * key in this property list. If the key is not
             * found in this property list, the default
             * property list, and its defaults, recursively,
             * are then checked. The method returns the
             * default value argument if the property is not
             * found.
             */

            String user = p.getProperty("user", "system");
            String password = p.getProperty("password", "Oracle");

            System.out.println("user = "+user);
            System.out.println("password = "+password);
        }
        finally
        {
            if (fileReader != null)
            {
                fileReader.close();
            }
        }
    }
}