diff --git "a/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo01.java" "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo01.java"
new file mode 100644
index 0000000000000000000000000000000000000000..07c89c26c5d2eb9bb395acda0257950527a2eb24
--- /dev/null
+++ "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo01.java"
@@ -0,0 +1,19 @@
+package JavaReview;
+
+public class Demo01 {
+
+	public static void main(String[] args) {
+		// 已知两个整数变量a = 10，b = 20，使用程序实现这两个变量的数据交换
+//		​        最终输出a = 20，b = 10;
+		
+		int a = 10 ;
+		int b = 20 ;
+		int temp ;
+		
+		temp = a ;
+		a = b ;
+		b = temp ;
+
+	}
+
+}
diff --git "a/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo02.java" "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo02.java"
new file mode 100644
index 0000000000000000000000000000000000000000..0f0e049c896062c689752bfa44c8af88c3e37784
--- /dev/null
+++ "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo02.java"
@@ -0,0 +1,86 @@
+package JavaReview;
+
+import java.util.Iterator;
+import java.util.Scanner;
+
+public class Demo02 {
+
+	public static void main(String[] args) {
+		// �÷���ʵ�����������
+//		����һ��������ʵ������Ӵ�С����
+//		����һ���������飬����һ���Ӵ�С��������顣
+		
+		Scanner scan = new Scanner(System.in) ;
+		
+		int[] arr = new int[5] ;
+		
+		for (int i = 0; i < arr.length; i++) {
+			System.out.println("������һ�����֣�");
+			arr[i] = scan.nextInt() ;
+		}
+		
+		System.out.println("����ǰ��");
+		printArr(arr);
+		
+		System.out.println("������һ�����֣�");
+		int num = scan.nextInt();
+		
+		int[] b = strcArr(arr, num);
+		
+		System.out.println("ת����");
+		printArr(b);
+
+	}
+	
+	public static void printArr(int[] arr) {
+		System.out.print("[");
+		
+		for (int i = 0; i < arr.length; i++) {
+			if (i == arr.length - 1) {
+				System.out.print(arr[i]);
+			}else {
+				System.out.print(arr[i]);
+				System.out.print(",");
+			}
+		}
+		
+		System.out.println("]");
+	}
+	
+	public static int[] strcArr(int[] arr ,int num) {
+		
+		int[] newarr = new int[arr.length+1];
+		
+		for (int i = 0; i < arr.length -1; i++) {
+			for (int j = 0; j < arr.length -1; j++) {
+				if (arr[j] < arr[j + 1]) {
+					int temp = arr[j] ;
+					arr[j] = arr[j + 1] ;
+					arr[j+1] = temp ; 
+				}
+			}
+		}
+		
+		int index = -1 ;
+		
+		for (int i = 0; i < arr.length; i++) {
+			if (num < arr[i]) {
+				index = i ;
+				break;
+			}
+		}
+		
+		for (int i = 0; i < newarr.length; i++) {
+			if (index > i) {
+				newarr[i] = arr[i];
+			}else if (index == i) {
+				newarr[i] = num ;
+			}else if (index < i) {
+				newarr[i] = arr[i - 1];
+			}
+		}
+		
+		return newarr;
+	}
+
+}
diff --git "a/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo03.java" "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo03.java"
new file mode 100644
index 0000000000000000000000000000000000000000..b593dd9999ea1785b0c83d65d9bb4719b0623b3c
--- /dev/null
+++ "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo03.java"
@@ -0,0 +1,22 @@
+package JavaReview;
+
+import java.util.Random;
+
+public class Demo03 {
+
+	public static void main(String[] args) {
+		// ����һ��������ʵ�ֵĹ����ǣ�����������п���7λ�������ص����ݸ�ʽ�磺0586 756
+//		Random
+//		����
+//		�ַ�����ȡ
+		
+		Random ran = new Random();
+		
+		int num1 = ran.nextInt(9999) ;
+		int num2 = ran.nextInt(999);
+		
+		System.out.println(num1 + "" + num2);
+
+	}
+
+}
diff --git "a/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo04.java" "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo04.java"
new file mode 100644
index 0000000000000000000000000000000000000000..49ea733ed6cb1fbd2a0152f64f21a45b65530ed9
--- /dev/null
+++ "b/\346\226\271\346\263\225\345\244\215\344\271\2402/\345\217\266\347\234\237/Demo04.java"
@@ -0,0 +1,54 @@
+package JavaReview;
+
+public class Demo04 {
+
+	public static void main(String[] args) {
+		// 定义一个方法，用来实现如下功能：
+//		​	已知一个数组 arr = {19, 28, 37, 46, 50};
+//		用程序实现把数组中的元素值交换，
+//		​	交换后的数组 arr = {50, 46, 37, 28, 19}; 
+//		并在控制台输出交换后的数组元素
+		
+		int[] arr = {19,28,37,46,50} ;
+		
+		System.out.println("转换前：");
+		printArr(arr);
+		
+		exchangeArr(arr);
+		System.out.println("转换后：");
+		printArr(arr);
+
+	}
+	public static int[] exchangeArr(int[] arr) {
+		
+		for (int start = 0,end = arr.length - 1; start < arr.length - 1; start++,end--) {
+			if (start == end) {
+				break;
+			}else {
+				if (start < end) {
+					int temp = arr[start] ;
+					arr[start] = arr[end] ;
+					arr[end] = temp ;
+				}
+			}
+		}
+		
+		return arr;
+	}
+	
+	public static void printArr(int[] arr) {
+		System.out.print("[");
+		
+		for (int i = 0; i < arr.length; i++) {
+			if (i == arr.length - 1) {
+				System.out.print(arr[i]);
+			}else {
+				System.out.print(arr[i]);
+				System.out.print(",");
+			}
+		}
+		
+		System.out.println("]");
+	}
+
+}