输入与输出

输入

获取用键盘输入常用的两种方法

方法 1：通过 Scanner

Scanner input = new Scanner(System.in);
String s  = input.nextLine();
input.close();

方法 2：通过 BufferedReader

BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
String s = input.readLine();

输出

System.out.println("字符串");//换行打印
System.out.print("\n");//换行打印
System.out.print("字符串");//换行打印
System.out.print(a);//不换行打印变量
System.out.print("字符串"+a);//混合输出字符串和变量值
System.out.printf("%");//按格式输出

printf 格式化输出符号详细说明_xiexievv的专栏-CSDN博客_printf格式化输出

格式化输入与输出

%

Converter	Flag	Explanation
d		A decimal integer.
f		A float.
n		A new line character appropriate to the platform running the application. You should always use %n, rather than \n.
tB		A date & time conversion—locale-specific full name of month.
td, te		A date & time conversion—2-digit day of month. td has leading zeroes as needed, te does not.
ty, tY		A date & time conversion—ty = 2-digit year, tY = 4-digit year.
tl		A date & time conversion—hour in 12-hour clock.
tM		A date & time conversion—minutes in 2 digits, with leading zeroes as necessary.
tp		A date & time conversion—locale-specific am/pm (lower case).
tm		A date & time conversion—months in 2 digits, with leading zeroes as necessary.
tD		A date & time conversion—date as %tm%td%ty
	08	Eight characters in width, with leading zeroes as necessary.
	+	Includes sign, whether positive or negative.
	,	Includes locale-specific grouping characters.
	-	Left-justified…
	.3	Three places after decimal point.
	10.3	Ten characters in width, right justified, with three places after decimal point.

        float a=0.23456f;
        System.out.format("a保留3位小数：%.3f",a);//a保留3位小数：0.235

DecimalFormat