immutable Set static factory methods in Java 9

thangpt2019 · thangpt2019 · commit 0769f11c5bbc · 2017-12-31T23:15:03.000+09:00
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,26 @@
+# Eclipse
+.project
+.classpath
+.settings/
+ 
+# Idea
+.idea/
+*.iml
+*.iws
+*.ipr
+ 
+# OS
+Thumbs.db
+.DS_Store
+ 
+# Maven
+target/
+ 
+# Build
+out/
+build/
+bin/
+
+ 
+# Others
+*.log
diff --git a/java9-language-features-examples/src/test/java/com/howtoprogram/java9ex/Java9SetFactoryMethodTest.java b/java9-language-features-examples/src/test/java/com/howtoprogram/java9ex/Java9SetFactoryMethodTest.java
@@ -0,0 +1,101 @@
+package com.howtoprogram.java9ex;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.*;
+import java.util.*;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+
+public class Java9SetFactoryMethodTest {
+
+
+    @Test
+    public void testImmutableSetJava9() {
+
+        Set<String> japanNoodles = Set.of("Ramen", "Yakisoba", "Udon", "Soba", "Somen");
+        assertEquals(5, japanNoodles.size());
+    }
+
+    @Test
+    public void testImmutableSetNotModified() {
+
+
+        Set<String> japanNoodles = Set.of("Ramen", "Yakisoba", "Udon", "Soba", "Somen");
+
+        assertEquals(5, japanNoodles.size());
+
+        assertThrows(UnsupportedOperationException.class, () -> {
+            // Add more element
+            japanNoodles.add("Negi");
+            // Remove element
+            japanNoodles.remove(1);
+        });
+
+    }
+
+    @Test
+    public void testImmutableSetNullAttempts() {
+
+        assertThrows(NullPointerException.class, () -> {
+            Set<String> stringList = Set.of(null);
+        });
+
+    }
+
+    @Test
+    public void testImmutableSetRejectDupplicates() {
+
+        assertThrows(IllegalArgumentException.class, () -> {
+            Set<?> teaSet = Set.of("Shincha", "Aki Bancha", "Hojicha", "Hojicha");
+        });
+
+    }
+
+    @Test
+    public void testImmutableSetMutableElements() {
+
+        Map<Integer, String> noodleToppingsMap = new HashMap<>();
+        noodleToppingsMap.put(1, "Negi");
+        noodleToppingsMap.put(2, "Tamago");
+        noodleToppingsMap.put(3, "Nori");
+
+        Map<Integer, String> japanTeaMap = new HashMap<>();
+        japanTeaMap.put(1, "Ryokucha");
+        japanTeaMap.put(2, "Yamecha");
+        japanTeaMap.put(3, "Ujicha");
+
+        List<Map<Integer, String>> choices = List.of(noodleToppingsMap, japanTeaMap);
+
+        assertEquals(3, choices.get(0).size());
+
+        //Add more elements to the mutable element of the List
+        noodleToppingsMap.put(3, "Tsuyu");
+        choices.get(0).put(4, "Aracha");
+
+        assertEquals(4, choices.get(0).size());
+
+    }
+
+    @Test
+    public void testImmutableSetSerializable() throws IOException {
+
+        Set<String> drinks = Set.of("Gyokuro", "Tamaryokucha", "Kamairicha");
+        //serialize the list
+        ObjectOutputStream oos = new ObjectOutputStream(System.out);
+        oos.writeObject(drinks);
+
+        //create a list of non-serializable objects
+        List<OutputStream> outputStreamList = List.of(new ByteArrayOutputStream(),
+                new PrintStream(System.out));
+
+        assertThrows(NotSerializableException.class, () -> {
+
+                    oos.writeObject(outputStreamList);
+                }
+        );
+    }
+
+}
