HashMap和TreeMap

src/chapter6/Example14.java

@@ -1,4 +1,27 @@
 package chapter6;
 
+import java.util.HashMap;
+
 public class Example14 {
+    public static void main(String[] args) {
+        HashMap map = new HashMap(); // 创建Map对象
+        map.put("1","张三");//存储键和值
+        map.put("2","李四");
+        map.put("3","王五");
+        map.put("3", "赵六");
+
+        System.out.println("1：" + map.get("1")); // 根据键获取值
+        System.out.println("2: " + map.get("2"));
+        System.out.println("3: " + map.get("3"));
+        System.out.println("键值对数量：" + map.size());
+
+//        if (map.containsKey("1")) {
+//            System.out.println("1号存在");
+//        }
+//
+//        if (map.containsValue("李四")) {
+//            System.out.println("李四存在");
+//        }
+
+    }
 }

src/chapter6/Example15.java

@@ -1,4 +1,52 @@
 package chapter6;
 
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+
 public class Example15 {
+    public static void main(String[] args) {
+        HashMap map = new HashMap(); // 创建Map对象
+        map.put("2","李四");          //存储键和值
+        map.put("3","王五");
+        map.put("1","张三");
+
+        // 方法一
+        Set keySet = map.keySet();      //获取键的集合
+        Iterator it = keySet.iterator();//选代键的集合
+        while (it.hasNext()) {
+            Object key = it.next();
+            Object value = map.get(key); //获取每个键所对应的值
+            System.out.println(key + ":" + value);
+        }
+
+        Iterator it2 = map.keySet().iterator();
+        while (it2.hasNext()) {
+            Object key = it2.next();
+            System.out.println(key);
+        }
+
+        Iterator it3 = map.values().iterator();
+        while (it3.hasNext()) {
+            Object value = it3.next();
+            System.out.println(value);
+        }
+
+        // 方法二
+        Set entrySet = map.entrySet();          // 获取所有映射关系
+        Iterator it4 = entrySet.iterator();   // 获取Iterator对象
+        while (it4.hasNext()){
+            //获取集合中键值对映射关系
+            Map.Entry entry = (Map.Entry) (it4.next());
+            Object key = entry.getKey();//获取Entry中的键
+            Object value = entry.getValue();//获取Entry中的值
+            System.out.println(key + ":" + value);
+        }
+
+        for (Object obj : map.entrySet()) {
+            System.out.println(obj);
+        }
+
+    }
 }

src/chapter6/Example19.java

@@ -1,4 +1,23 @@
 package chapter6;
 
+import java.util.Iterator;
+import java.util.Set;
+import java.util.TreeMap;
+
 public class Example19 {
+    public static void main(String[] args) {
+        TreeMap map = new TreeMap();      // 创建Map集合
+        map.put(3, "李四");               // 存储键和值
+        map.put(2, "王五");
+        map.put(4, "赵六");
+        map.put(3, "张三");
+
+        Set keySet = map.keySet();
+        Iterator iterator = keySet.iterator();
+        while (iterator.hasNext()) {
+            Object key = iterator.next();
+            Object value = map.get(key);
+            System.out.println(key + ":" + value);
+        }
+    }
 }