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--- codding:java8_lambda_use_cases [2014/08/21 07:52] – created yehuda
+++ codding:java8_lambda_use_cases [2022/01/03 16:03] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== Java8 Lambda Use cases ======
+===== Runnable =====
+Instead using:
+<code java>
+public class RunnableTest {
+  public static void main(String[] args) {
+    System.out.println("=== RunnableTest ===");
+    Runnable r = new Runnable(){
+      @Override
+      public void run(){
+        System.out.println("Hello world one!");
+      }
+    };
+    r.run();
+  }
+}
+</code>
+Use:
+<code java>
+public class RunnableTest {
+  public static void main(String[] args) {
+    System.out.println("=== RunnableTest ===");
+    Runnable r = () -> System.out.println("Hello world two!");
+    r.run();
+  }
+}
+</code>
+===== Listener =====
+Java Way
+<code java>
+public class ListenerTest {
+  public static void main(String[] args) {
+    JButton testButton = new JButton("Test Button");
+    testButton.addActionListener(new ActionListener(){
+    @Override public void actionPerformed(ActionEvent ae){
+        System.out.println("Click Detected by Anon Class");
+      }
+    });
+    // Swing stuff
+    JFrame frame = new JFrame("Listener Test");
+    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+    frame.add(testButton, BorderLayout.CENTER);
+    frame.pack();
+    frame.setVisible(true);
+  }
+}
+</code>
+Lambda Way
+<code java>
+public class ListenerTest {
+  public static void main(String[] args) {
+    JButton testButton = new JButton("Test Button");
+    testButton.addActionListener(e -> System.out.println("Click Detected by Lambda Listner"));
+    // Swing stuff
+    JFrame frame = new JFrame("Listener Test");
+    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+    frame.add(testButton, BorderLayout.CENTER);
+    frame.pack();
+    frame.setVisible(true);
+  }
+}
+</code>
+===== Improve Code =====
+Java Way
+<code java>
+public class Person {
+new Thread(new Runnable() {
+    @Override
+    public void run() {
+        System.out.println("Hello from thread");
+    }
+}).start();
+</code>
+Lambda Way
+<code java>
+new Thread(
+    () -> System.out.println("Hello from thread")
+).start();
+</code>
+===== Foreach =====
+Define:
+<code java>
+List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
+</code>
+Java Way
+<code java>
+for(Integer n: list) {
+    System.out.println(n);
+}
+</code>
+Lambda Way
+<code java>
+list.forEach(n -> System.out.println(n));
+</code>
+Java8 Way
+<code java>
+list.forEach(System.out::println);
+</code>
+===== Foreach and Multiply =====
+<code java>
+List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
+</code>
+Java Way
+<code java>
+for(Integer n : list) {
+    int x = n * n;
+    System.out.println(x);
+}
+</code>
+Lambda Way
+<code java>
+list.stream().map((x) -> x*x).forEach(System.out::println);
+</code>
+===== MapReduce in java=====
+<code java>
+List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
+</code>
+Java Way
+<code java>
+int sum = 0;
+for(Integer n : list) {
+    int x = n * n;
+    sum = sum + x;
+}
+System.out.println(sum);
+</code>
+Lambda Way
+<code java>
+int sum = list.stream().map(x -> x*x).reduce((x,y) -> x + y).get();
+System.out.println(sum);
+</code>

codding/java8_lambda_use_cases.1408607552.txt.gz · Last modified: 2022/01/03 16:03 (external edit)

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