Added some generics related examples.

Author: bhuwang

file_writer_demo.txt

@@ -1,4 +1,4 @@
-B100
-true
-10.2
 Bhuwan
+Hello BufferWriter!!
+ABC
+X

src/com/bhuwan/java/generics/BoundedType.java

@@ -19,7 +19,7 @@ public class BoundedType {
     public static <T extends Comparable<T>> int compare(T t1, T t2) {
         return t1.compareTo(t2);
     }
-    
+
     @SuppressWarnings("unused")
     public static void main(String[] args) {
         String name = "Bhuwan";

src/com/bhuwan/java/generics/ErasureDemo.java

@@ -26,4 +26,22 @@ public static void One(ArrayList<String> s) {
     // public static void One(ArrayList<Integer> s) {
     // }
 
+    public <T extends Happy> T foo(T emotion) {
+        // do something
+        return null;
+    }
+
+    public <T extends Sad> T foo(T emotion) {
+        return null;
+        // do something else
+    }
+
+}
+
+class Happy {
+
+}
+
+class Sad {
+
 }

src/com/bhuwan/java/generics/GenericsAndInheritance.java

@@ -17,7 +17,7 @@ public static void main(String[] args) {
         // this is not same with generic
         // object = nameString;
 
-        InheritanceDemo3<String> abc = new InheritanceDemo3();
+        InheritanceDemo4<CustomRunnableDemo> abc = new InheritanceDemo4();
         InheritanceDemo3<Object> xyz = new InheritanceDemo3();
     }
 }
@@ -37,6 +37,11 @@ class InheritanceDemo2<T extends Number & Comparable & Runnable> {
 
 }
 
+// syntax three
+class InheritanceDemo4<T extends Runnable> {
+
+}
+
 /**
  * syntax four
  * 
@@ -46,6 +51,10 @@ class InheritanceDemo2<T extends Number & Comparable & Runnable> {
 // }
 
 // syntax five
-class InheritanceDemo3<T>{
-    
+class InheritanceDemo3<T> {
+
+}
+
+class CustomRunnableDemo extends Thread {
+
 }

src/com/bhuwan/java/generics/GenericsLowerBounded.java

@@ -13,7 +13,7 @@ public class GenericsLowerBounded {
 
     public static void main(String[] args) {
         // it only accepts Number or Object type
-        List<Number> ints = new ArrayList<>();
+        List<Object> ints = new ArrayList<>();
         ints.add(3);
         ints.add(5);
         ints.add(10);

src/com/bhuwan/java/generics/TestGenerics.java

@@ -0,0 +1,55 @@
+/**
+ * 
+ */
+package com.bhuwan.java.generics;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * @author bhuwan
+ *
+ */
+public class TestGenerics {
+
+    public static void main(String[] args) {
+        List list = new ArrayList();
+        list.add(123);
+        list.add("Bhuwan");
+        list.add(12.22);
+        list.add(123.1f);
+
+        Double name = (Double) list.get(1);
+
+        System.out.println(list);
+        System.out.println(name);
+
+        List<Integer> cities = new ArrayList<>();
+        cities.add(1232);
+
+        CustomGenerics<Integer> numbers = new CustomGenerics<>();
+        numbers.setT(1223);
+    }
+
+}
+
+class CustomGenerics<T extends Number> {
+
+    private T t;
+
+    /**
+     * @return the t
+     */
+    public T getT() {
+        return t;
+    }
+
+    /**
+     * @param t
+     *            the t to set
+     */
+    public void setT(T t) {
+        this.t = t;
+    }
+
+}

src/com/bhuwan/java/generics/UsingGenerics.java

@@ -11,7 +11,7 @@
  */
 public class UsingGenerics {
 
-    private static final Logger log = Logger.getLogger(WithoutUsingGenerics.class.getName());
+    private static final Logger log = Logger.getLogger(UsingGenerics.class.getName());
 
     public static void main(String args[]) {
 
@@ -20,10 +20,10 @@ public static void main(String args[]) {
 
         // add marks
         marksList.add(94.0);
-        //marksList.add("Hundred");
+        // marksList.add("Hundred");
         marksList.add(90.0);
-        //compile-time error
-        //marksList.add(72);
+        // compile-time error
+        // marksList.add(72);
 
         log.info("Percentage:: " + calculatePercentage(marksList));
     }

src/com/bhuwan/java/io/file/BufferedWriterDemo.java

@@ -19,9 +19,9 @@ public class BufferedWriterDemo {
      */
     public static void main(String[] args) throws IOException {
         try (BufferedWriter bw = new BufferedWriter(new FileWriter("file_writer_demo.txt", true));
-                BufferedWriter bw1 = new BufferedWriter(new FileWriter("file_writer_demo.txt"));
+                BufferedWriter bw1 = new BufferedWriter(new FileWriter("file_writer_demo1.txt"));
                 // initializing double buffered writer object.
-                BufferedWriter bw2 = new BufferedWriter(new BufferedWriter(new FileWriter("file_writer_demo.txt")));) {
+                BufferedWriter bw2 = new BufferedWriter(new BufferedWriter(new FileWriter("file_writer_demo1.txt")));) {
             bw.write(66);
             bw.write("huwan");
             bw.newLine();