Java Console I/O Java控制台输入与输出

输出

print() 输出对象的toString()方法的内容

println() 加上回车换行

输入

1. BufferedReader

01// MAKE SURE TO IMPORT java.io.*!!!!

02import java.io.*;

03 

04public class test

05{

06    public static void main(String[] args)

07    {

08        // this line is not necessary, but most people use it

09        // System.in is the keyboard input stream

10        InputStreamReader rdr = new InputStreamReader(System.in);

11 

12        // use the InputStreamReader as the parameter to read from keyboard

13        BufferedReader reader = new BufferedReader(rdr);

14 

15        // prompt for what to enter

16        System.out.print("Enter a number: ");

17 

18        // get the input (ALWAYS A STRING)

19        String in = reader.readLine();

20 

21        // transfer that String to an integer

22        int number = Integer.parseInt(in);

23 

24        // output the number

25        System.out.println(number);

26    }

27}

BufferReader的缺陷

输入数据的类型总是String，需要将String对象解析为整型或者其他类型的数据。而且它允许你输入任何内容， 在运行时可能产生错误或异常。

2. Scanner (JDK 1.5版本以上)

支持多数据类型的输入，易于使用。

01// does NOT use java.io

02import java.util.Scanner;

03 

04public class test

05{

06    public static void main(String[] args)

07    {

08        // much easier declaration

09        Scanner scan = new Scanner(System.in);

10 

11        // prompt for input

12        System.out.print("Enter a number: ");

13 

14        // get the input, NO PARSING.

15        // The nextInt() method prevents the user

16        // from crashing the program here...

17        // As it only accepts number(s) as input

18        int number = scan.nextInt();

19 

20        // output the number

21        System.out.println(number);

22    }

23}

3. Console

未完待续