diff --git a/DaffodilsNum.java b/DaffodilsNum.java
new file mode 100644
index 0000000..13e5299
--- /dev/null
+++ b/DaffodilsNum.java
@@ -0,0 +1,36 @@
+    public class DaffodilsNum {
+        public static void main(String[] args) {
+            Scanner in = new Scanner(System.in);
+            System.out.print("请输入0-1000内的数字: ");
+            int num = in.nextInt();
+            in.close();
+
+            // 1. 判断输入是否合法
+            if (num < 0 || num > 1000) {
+                System.out.println("输入的不是0-1000内的数字!");
+                return;
+            }
+
+
+            if (num < 100 || num > 999) {
+                System.out.println(num + "不是水仙花数!");
+                return;
+            }
+
+
+            int ge = num % 10;
+            int shi = num / 10 % 10;
+            int bai = num / 100;
+
+
+            int sum = ge * ge * ge + shi * shi * shi + bai * bai * bai;
+
+
+            if (sum == num) {
+                System.out.println(num + "是水仙花数!");
+            } else {
+                System.out.println(num + "不是水仙花数!");
+            }
+        }
+    }
+}
diff --git a/LeapYear.java b/LeapYear.java
new file mode 100644
index 0000000..c2d5248
--- /dev/null
+++ b/LeapYear.java
@@ -0,0 +1,27 @@
+public class LeapYear {
+        public static void main(String[] args) {
+            Scanner scan = new Scanner(System.in);
+            System.out.print("请输入2000~3000内的年数!");
+            int year = scan.nextInt();
+            scan.close();
+
+
+            if (year < 2000 || year > 3000) {
+                System.out.println("请输入2000~3000内的年数!");
+                return;
+            }
+
+
+            boolean isLeap = false;
+            if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
+                isLeap = true;
+            }
+
+
+            if (isLeap) {
+                System.out.println(year + "年是闰年");
+            } else {
+                System.out.println(year + "年不是闰年");
+            }
+        }
+    }
diff --git a/javaclass.java b/javaclass.java
new file mode 100644
index 0000000..f1b2cba
--- /dev/null
+++ b/javaclass.java
@@ -0,0 +1,40 @@
+import java.util.Scanner;
+import java.lang.Math;
+class EquationRoot
+{
+    public static void main(String[] args)
+    {
+        Scanner scan = new Scanner(System.in);
+        double a,b,c,disc,x1,x2,p,q;
+
+        System.out.print("请输入系数a=");
+        a = scan.nextDouble() ;
+
+        System.out.print("请输入系数b=");
+        b = scan.nextDouble() ;
+
+        System.out.print("请输入系数c=");
+        c = scan.nextDouble() ;
+
+        disc=b*b-4*a*c;
+
+        if ( Math.abs(disc) <= 1e-6 )
+            System.out.println("x1=x2="+(-b/(2*a)));
+        else
+        {
+            if(disc>1e-6)
+            {
+                x1=(-b+Math.sqrt(disc))/(2*a);
+                x2=(-b-Math.sqrt(disc))/(2*a);
+                System.out.printf("x1=%7.2f,x2=%7.2f\n", x1, x2);
+            }
+            else
+            {
+                p=-b/(2*a);
+                q=Math.sqrt(Math.abs(disc))/(2*a);
+                System.out.printf("x1=%7.2f + %7.2f i\n", p, q);
+                System.out.printf("x2=%7.2f - %7.2f i\n", p, q);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/javaclass2.java b/javaclass2.java
new file mode 100644
index 0000000..d31773f
--- /dev/null
+++ b/javaclass2.java
@@ -0,0 +1,23 @@
+
+    import java.util.Scanner;
+    class ScoreToGrade
+    {
+        public static void main(String[] args)
+        {
+            Scanner scan = new Scanner(System.in);
+            int i_score;
+            System.out.print("请输入分数 = ");
+            i_score = scan.nextInt();
+            i_score /=10;
+
+            switch(i_score)
+            {
+                case 10:
+                case 9:System.out.println("成绩为 优秀 !"); break;
+                case 8:System.out.println("成绩为 良好 !"); break;
+                case 7:System.out.println("成绩为 中等 !"); break;
+                case 6:System.out.println("成绩为 及格 !"); break;
+                default:System.out.println("成绩为 不及格 !");
+            }
+        }
+    }