BAEL-4790 - collection vs stream

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/streamvscollection/StreamVsCollectionExample.java

@@ -2,13 +2,17 @@ package com.baeldung.streams.streamvscollection;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.SortedSet;
+import java.util.TreeSet;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 public class StreamVsCollectionExample {
-    
+
     static ArrayList<String> userNameSource = new ArrayList<>();
-    
+
     static {
         userNameSource.add("john");
         userNameSource.add("smith");
@@ -17,33 +21,75 @@ public class StreamVsCollectionExample {
         userNameSource.add("charlie");
         userNameSource.add("alfred"); 
     }
-    
+
     public static Stream<String> userNames() {
         return userNameSource.stream();
     }
-    
+
     public static List<String> userNameList() {
         return userNames().collect(Collectors.toList());
     }
 
+    public static Set<String> userNameSet() {
+        return userNames().collect(Collectors.toSet());
+    }
+
+    public static Map<String, String> userNameMap() {
+        return userNames().collect(Collectors.toMap(u1 -> u1.toString(), u1 -> u1.toString()));
+    }
+
     public static Stream<String> filterUserNames() {
         return userNames().filter(i -> i.length() >= 4);
     }
-    
+
     public static Stream<String> sortUserNames() {
         return userNames().sorted();
     }
-    
+
     public static Stream<String> limitUserNames() {
         return userNames().limit(3);
     }
-    
+
     public static Stream<String> sortFilterLimitUserNames() {
         return filterUserNames().sorted().limit(3);
     }
-    
+
     public static void printStream(Stream<String> stream) {
         stream.forEach(System.out::println);
     }
+
+    public static void modifyList() {
+        userNameSource.remove(2);
+    }
+
+    public static Map<String, String> modifyMap() {
+        Map<String, String> userNameMap = userNameMap();
+        userNameMap.put("bob", "bob");
+        userNameMap.remove("alfred");
+
+        return userNameMap;
+    }
+
+    public static void tryStreamTraversal() {
+        Stream<String> userNameStream = userNames();
+        userNameStream.forEach(System.out::println);
+        
+        try {
+            userNameStream.forEach(System.out::println);
+        } catch(IllegalStateException e) {
+            System.out.println("stream has already been operated upon or closed");
+        }
+    }
+    
+    public static void main(String[] args) {
+        System.out.println(userNameMap());
+        System.out.println(modifyMap());      
+        tryStreamTraversal();
+        
+        Set<String> set = userNames().collect(Collectors.toCollection(TreeSet::new));
+        set.forEach(val -> System.out.println(val));  
+        
+    }
+    
     
 }