diff --git a/java/ALineCode.java b/java/ALineCode.java
new file mode 100644
index 0000000000000000000000000000000000000000..e1dcc87284aa315a186f4efdd9e800bbee824fed
--- /dev/null
+++ b/java/ALineCode.java
@@ -0,0 +1,20 @@
+package spring;
+
+
+public class B {
+
+
+    public static void main(String[] args)  {
+        System.out.println(isTwoPower(15));
+    }
+
+    /**
+     * 看不懂的代码
+     * @param n
+     * @return
+     */
+    public static boolean isTwo(int n){
+        return (n & n-1) == 0;
+    }
+
+}