core-java Properties class demos

core-java/src/main/java/com/baeldung/properties/DefaultListDemo.java

@@ -0,0 +1,23 @@
+package com.baeldung.properties;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Properties;
+
+public class DefaultListDemo {
+    public static void main(String[] args) throws IOException {
+        String rootPath = Thread.currentThread().getContextClassLoader().getResource("").getPath();
+        String defaultConfigPath = rootPath + "default.properties";
+        String appConfigPath = rootPath + "app.properties";
+
+        Properties defaultProps = new Properties();
+        defaultProps.load(new FileInputStream(defaultConfigPath));
+
+        Properties appProps = new Properties(defaultProps);
+        appProps.load(new FileInputStream(appConfigPath));
+
+        System.out.println(appProps.getProperty("name"));
+        System.out.println(appProps.getProperty("version"));
+        System.out.println(appProps.getProperty("site"));
+    }
+}

core-java/src/main/java/com/baeldung/properties/LoadDemo.java

@@ -0,0 +1,26 @@
+package com.baeldung.properties;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Properties;
+
+public class LoadDemo {
+    public static void main(String[] args) throws IOException {
+        String rootPath = Thread.currentThread().getContextClassLoader().getResource("").getPath();
+        String appConfigPath = rootPath + "app.properties";
+        String catalogConfigPath = rootPath + "catalog";
+        String iconConfigPath = rootPath + "icons.xml";
+
+        // load from properties file which use .properties as the suffix
+        Properties appProps = new Properties();
+        appProps.load(new FileInputStream(appConfigPath));
+
+        // load from properties file which not use .properties as the suffix
+        Properties catalogProps = new Properties();
+        catalogProps.load(new FileInputStream(catalogConfigPath));
+
+        // load from XML file
+        Properties iconProps = new Properties();
+        iconProps.loadFromXML(new FileInputStream(iconConfigPath));
+    }
+}

core-java/src/main/java/com/baeldung/properties/OperationsDemo.java

@@ -0,0 +1,57 @@
+package com.baeldung.properties;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Enumeration;
+import java.util.Properties;
+
+public class OperationsDemo {
+    public static void main(String[] args) throws IOException {
+        String rootPath = Thread.currentThread().getContextClassLoader().getResource("").getPath();
+        String appConfigPath = rootPath + "app.properties";
+        Properties appProps = new Properties();
+        appProps.load(new FileInputStream(appConfigPath));
+
+        // retrieve values
+        String appVersion = appProps.getProperty("version");
+        String appName = appProps.getProperty("name", "defaultName");
+        String appGroup = appProps.getProperty("group", "baeldung");
+        String appDownloadAddr = appProps.getProperty("downloadAddr");
+        System.out.println(appVersion);
+        System.out.println(appName);
+        System.out.println(appGroup);
+        System.out.println(appDownloadAddr);
+
+        // set values
+        appProps.setProperty("name", "NewAppName");
+        appProps.setProperty("downloadAddr", "www.baeldung.com/downloads");
+        appName = appProps.getProperty("name");
+        appDownloadAddr = appProps.getProperty("downloadAddr");
+        System.out.println("new app name: " + appName);
+        System.out.println("new app downloadAddr: " + appDownloadAddr);
+
+        // remove a key-value pair
+        System.out.println("before removal, version is: " + appProps.getProperty("version"));
+        appProps.remove("version");
+        System.out.println("after removal, version is: " + appProps.getProperty("version"));
+
+        // list all key-value pairs
+        appProps.list(System.out);
+
+        // get an enumeration of all values
+        Enumeration<Object> valueEnumeration = appProps.elements();
+        while (valueEnumeration.hasMoreElements()) {
+            System.out.println(valueEnumeration.nextElement());
+        }
+
+        // get an enumeration of all keys
+        Enumeration<Object> keyEnumeration = appProps.keys();
+        while (keyEnumeration.hasMoreElements()) {
+            System.out.println(keyEnumeration.nextElement());
+        }
+
+        // get the count of key-value pairs
+        int size = appProps.size();
+        System.out.println(size);
+    }
+}

core-java/src/main/java/com/baeldung/properties/StoreDemo.java

@@ -0,0 +1,30 @@
+package com.baeldung.properties;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.Properties;
+
+public class StoreDemo {
+    public static void main(String[] args) throws IOException {
+        String rootPath = Thread.currentThread().getContextClassLoader().getResource("").getPath();
+        String appConfigPath = rootPath + "app.properties";
+
+        // load the original properties
+        Properties appProps = new Properties();
+        appProps.load(new FileInputStream(appConfigPath));
+
+        // update property list
+        appProps.setProperty("name", "NewAppName");
+        appProps.setProperty("downloadAddr", "www.baeldung.com/downloads");
+
+        // store new property list in properties file
+        String newAppConfigPropertiesFile = rootPath + "newApp.properties";
+        appProps.store(new FileWriter(newAppConfigPropertiesFile), "store to properties file");
+
+        // store new property list in XML file
+        String newAppConfigXmlFile = rootPath + "newApp.xml";
+        appProps.storeToXML(new FileOutputStream(newAppConfigXmlFile), "store to xml file");
+    }
+}

core-java/src/main/resources/app.properties

@@ -0,0 +1,3 @@
+version=1.0
+name=TestApp
+date=2016-11-12

core-java/src/main/resources/catalog

@@ -0,0 +1,3 @@
+c1=files
+c2=images
+c3=videos

core-java/src/main/resources/default.properties

@@ -0,0 +1,4 @@
+site=www.google.com
+name=DefaultAppName
+topic=Properties
+category=core-java

core-java/src/main/resources/icons.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
+<properties>
+    <comment>xml example</comment>
+    <entry key="fileIcon">icon1.jpg</entry>
+    <entry key="imageIcon">icon2.jpg</entry>
+    <entry key="videoIcon">icon3.jpg</entry>
+</properties>