Add Java and C++ code for the section hash algorithm (#560)

codes/java/chapter_hashing/built_in_hash.java

@@ -0,0 +1,38 @@
+/**
+ * File: built_in_hash.java
+ * Created Time: 2023-06-21
+ * Author: Krahets (krahets@163.com)
+ */
+
+package chapter_hashing;
+
+import utils.*;
+import java.util.*;
+
+public class built_in_hash {
+    public static void main(String[] args) {
+        int num = 3;
+        int hashNum = Integer.hashCode(num);
+        System.out.println("整数 " + num + " 的哈希值为 " + hashNum);
+
+        boolean bol = true;
+        int hashBol = Boolean.hashCode(bol);
+        System.out.println("布尔量 " + bol + " 的哈希值为 " + hashBol);
+
+        double dec = 3.14159;
+        int hashDec = Double.hashCode(dec);
+        System.out.println("小数 " + dec + " 的哈希值为 " + hashDec);
+
+        String str = "Hello 算法";
+        int hashStr = str.hashCode();
+        System.out.println("字符串 " + str + " 的哈希值为 " + hashStr);
+
+        Object[] arr = { 12836, "小哈" };
+        int hashTup = Arrays.hashCode(arr);
+        System.out.println("数组 " + Arrays.toString(arr) + " 的哈希值为 " + hashTup);
+
+        ListNode obj = new ListNode(0);
+        int hashObj = obj.hashCode();
+        System.out.println("节点对象 " + obj + " 的哈希值为 " + hashObj);
+    }
+}