Core Java 8 学习笔记（三） 输入输出

一、用Scanner读取输入

Java的读取输入比C++麻烦一点点，Scanner用法示例如下：

package v1_chapter3;import java.io.Console;import java.util.Scanner;public class InputTest {public static void main(String args[]) {Scanner in = new Scanner(System.in);System.out.println("What do you want to say?");// 读入一行字符串String msg = in.nextLine();System.out.println(msg);System.out.print("What is your name?");// 读一个单词String name = in.next();System.out.println("How old are you?");//读一个整数Integer age = in.nextInt();System.out.println("Hello, " + name);System.out.println("U are " + age.toString() + "years old.");System.out.println("How tall are you?");//读一个浮点数Double lengthDouble = in.nextDouble();System.out.println("You are just " + lengthDouble.toString() + " meters tall.");in.close();/* 不知道Console怎么用 *Console cons = System.console(); *String userName = cons.readLine("User Name: "); *// 读入密码的时候，必须用 char[] *char[] pass = cons.readPassword("Password: "); *System.out.println("Hello, " + userName + "\nThe key is: " + pass[]); */}}

二、格式化输出

1. 调用System.out.printf("%s", var)进行格式化输出。用法和C语言中基本类似。

2. 调用String.format("%s", var)函数进行格式化，可以赋值而不用输出。

3. System.out.printf("%1$s %2$tB %2$te, %2$tY", "Due date: ", new Date()) 可以格式化输出日期

三、文件读写

太复杂，待补充。