diff --git a/day03/src/com/inmind/if01/Demo03.java b/day03/src/com/inmind/if01/Demo03.java
index 56862d7..49e6873 100644
--- a/day03/src/com/inmind/if01/Demo03.java
+++ b/day03/src/com/inmind/if01/Demo03.java
@@ -27,4 +27,19 @@ public class Demo03 {
     当x<‐1 y = 2x – 1;
     根据给定的x的值，计算出y的值并输出。
     */
+    public static void main(String[] args) {
+        int x = 2;
+        int y;
+        if (x >= 3) {
+            y = 2*x + 1;
+        } else if (x >= -1 && x < 3) {
+            y = 2 * x;
+        } else {
+            y = 2 * x - 1;
+        }
+
+        System.out.println("x的值是"+x+"，y的值是"+y);
+
+        System.out.println("程序结束");
+    }
 }