饿汉式单例实现

src/main/java/top/fjy8018/designpattern/pattern/creational/singleton/HungrySingleton.java

@@ -0,0 +1,28 @@
+package top.fjy8018.designpattern.pattern.creational.singleton;
+
+/**
+ * 单例模式：饿汉式（类加载时初始化）
+ * 优点：写法简单，类加载时初始化，线程安全
+ * 缺点：若类不被使用则会造成内存浪费
+ *
+ * @author F嘉阳
+ * @date 2018-09-24 15:38
+ */
+public class HungrySingleton {
+    /**
+     * 类加载时初始化
+     * 声明final（可选），只有在类加载时初始化才能声明为final，故懒汉式不能声明为final
+     */
+    private static final HungrySingleton HUNGRYSINGLETON;
+
+    static {
+        HUNGRYSINGLETON = new HungrySingleton();
+    }
+
+    private HungrySingleton() {
+    }
+
+    public static HungrySingleton getInstance() {
+        return HUNGRYSINGLETON;
+    }
+}