JAVA输出流与输入流

1 public class C {
2     public static void main(String[] args) {
3         System.out.println("Holle JAVA");   //输出
4 　　}
5 }

 1 import java.io.*;  //引入io包
 2 
 3 public class C {
 4     public static void main(String[] args) throws IOException {
 5 
 6         InputStreamReader isr = new InputStreamReader(System.in);
 7         BufferedReader br = new BufferedReader(isr);
 8         
 9         System.out.printf("请输入第一个数：");
10         //接收第一个数
11         String a = br.readLine();
12         
13         System.out.printf("请输入第二个数：");
14         //接收第一个数
15         String b = br.readLine();
16         
17         //String 转换 float
18         float num1 = Float.parseFloat(a);
19         float num2 = Float.parseFloat(b);
20 
21         System.out.println("a+b=" +(num1+num2));
22         System.out.println("a-b=" +(num1-num2));
23         System.out.println("a*b=" +(num1*num2));
24         System.out.println("a/b=" +(num1/num2));
25     }
26 }