Update codes of heap.java and my_heap.java

codes/java/chapter_heap/heap.java

@@ -0,0 +1,60 @@
+/**
+ * File: my_heap.java
+ * Created Time: 2023-01-07
+ * Author: Krahets (krahets@163.com)
+ */
+
+package chapter_heap;
+
+import include.*;
+import java.util.*;
+
+
+public class heap {
+    public static void testPush(Queue<Integer> heap, int val) {
+        // 元素入堆
+        heap.add(val);
+
+        System.out.format("\n添加元素 %d 后\n", val);
+        PrintUtil.printHeap(heap);
+    }
+
+    public static void testPoll(Queue<Integer> heap) {
+        // 元素出堆
+        int val = heap.poll();
+
+        System.out.format("\n出堆元素为 %d\n", val);
+        PrintUtil.printHeap(heap);
+    }
+
+    public static void main(String[] args) {
+        /* 初始化堆 */
+        // 初始化最小堆
+        Queue<Integer> minHeap = new PriorityQueue<>();
+        // 初始化最大堆（使用 lambda 表达式修改 Comparator）
+        Queue<Integer> maxHeap = new PriorityQueue<>((a, b) -> { return b - a; });
+
+        /* 元素入堆 */
+        testPush(maxHeap, 1);
+        testPush(maxHeap, 3);
+        testPush(maxHeap, 2);
+        testPush(maxHeap, 5);
+        testPush(maxHeap, 4);
+
+        /* 获取堆顶元素 */
+        int peek = maxHeap.peek();
+        System.out.format("\n堆顶元素为 %d\n", peek);
+
+        /* 元素出堆 */
+        testPoll(maxHeap);
+        testPoll(maxHeap);
+
+        /* 获取堆大小 */
+        int size = maxHeap.size();
+        System.out.format("\n堆元素数量为 %d\n", size);
+
+        /* 判断堆是否为空 */
+        boolean isEmpty = maxHeap.isEmpty();
+        System.out.format("\n堆是否为空 %b\n", isEmpty);
+    }
+}