Table of Contents
Java console output
1. Use System.out.write method output
2 Use the System.out.println method to output
3 Using System The .out.print method output
4 System.out.printf
Detailed introduction to formatted output
格式化整数
修饰符
数据的宽度
格式化浮点数
限制小数位数与宽度
String也可以调用format方法
Home Java javaTutorial What are the ways to format output in Java?

What are the ways to format output in Java?

May 08, 2023 pm 01:40 PM
java

    Java console output

    1. Use System.out.write method output

    You can output information to the console The write method using the output stream is just not as convenient to use as print and println. In fact, the print and println methods also encapsulate write and ultimately call write to write data to the console.
    When using write, you need to import IOException, that is, add import java.io.IOException in front of the java file; the write method may throw IOExcetion.
    I won’t introduce the write method in detail. It is better to use print or println usually.

    2 Use the System.out.println method to output

    To view it in idea, enter System.out .println() actually calls the following methods (function overloading)

    What are the ways to format output in Java?

    After calling System.out.println(), a newline will be added directly after the output. If you do not write parameters, it will only serve as a line break.

    If the parameter is char[], all elements in char[] will be output directly without any separators between the elements, as if a string is output.

    Another special parameter is Object. Object is the parent class of all classes in Java. If the parameter is an Object object, the address of the Object or null will be output directly unless the corresponding Object is overridden. I have my own toString method, so I won’t go into too much detail here.

    We can use string concatenation operations to output various formats, such as output: x=5, output the value of x

    int x=5;
    System.out.println("x="+x);
    Copy after login

    3 Using System The .out.print method output

    is only one less method without parameters than System.out.println().

    The only difference between System.out.print and System.out.println is that this one does not add newlines.

    What are the ways to format output in Java?

    4 System.out.printf

    The bottom layer of printf is format. There is no difference in the usage of the two methods. In fact, printf just calls Just format it

    What are the ways to format output in Java?

    Detailed introduction to formatted output

    System.out.format(); System.out.printf();

    The usage of both is the same. The format is used as an example below.

    When we need to format and output some data, just using System.out.println(); is not enough. At this time, we need to use the format method

    System .out provides the formatted output method format. The first parameter of format is a template. The template has some placeholders. The following parameters are used to replace the placeholders in the template to complete the output of the entire information.

    For example:

    String name="LiLi";
    int age=8;
    char sex='男';
    float grade=52.5;
    System.out.format("姓名:%s, 年龄:%d, 性别:%c, 成绩:%.1f\n", name, age, sex, grade);
    Copy after login

    Output: Name: LiLi, Age: 8, Gender: Male, Score: 52.5

    %c, %s, etc. are called placeholders symbols, representing characters and strings respectively, which will be replaced by the values ​​of the corresponding variables that appear later. Like %.1f, .f is added to %f to indicate outputting a 1-digit decimal.

    Commonly used placeholders:

    Placeholder Description
    %d Formatted output integer
    %f Formatted output floating point number
    %e Format floating point number in scientific notation
    %s Format output string

    当然不可能只有这么点了,下边才是大头????

    格式化整数

    既可以格式化基本数据类型,也可以格式化它们的包装类

    • %d :格式化十进制整数

    • %o :格式化八进制整数

    • %x :格式化小写十六进制整数,如:abc58

    • %X :格式化大写十六进制整数,如:ABC58

    修饰符
    • “+”:格式化正整数时强制添加上正好,如%+d可将123格式化位+123

    • “,”:格式化整数时按“千”分组,例如:%,d可将1234567890格式化位1,234,567,890

    它俩可以组合使用,如:%+,d

    数据的宽度

    %md或%-md指定格式化整数的长度最少为m

    如%6d可将123格式化为“ 123”,左边三个空格,即如果数字的长度不足6,则在格式化的数字左边添加空格使得整体长度为6(左边添加空格即右对齐

    %-6d使得结果左对齐,即在右边添加空格,如%-6d可将123格式化为“123 ”,右边三个空格

    格式化浮点数

    既可以格式化基本数据类型,也可以格式化它们的包装类

    修饰符
    • “+” :格式化正数时添加正号

    • “,”:将正数部分按千分位

    它俩可以组合使用,如:%+,f

    限制小数位数与宽度
    • “%.nf”可以限制小数的位数为n(遵循四舍五入)

    • “%mf”可以规定数据的宽度为m,长度不足补空格,默认居右(%-mf,居左)

    组合使用:

    System.out.printf("%7.3f",0.1235);
    Copy after login

    结果:0.124 (还有俩个空格,“.”也占一个长度)

    String也可以调用format方法

    String也可以调用format方法,用法与上述完全一致,结果返回一个字符串对象

    例:

    String s=String.format("%d",12345);
    Copy after login

    s的值为12345

    The above is the detailed content of What are the ways to format output in Java?. For more information, please follow other related articles on the PHP Chinese website!

    Statement of this Website
    The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

    Hot Article Tags

    Notepad++7.3.1

    Notepad++7.3.1

    Easy-to-use and free code editor

    SublimeText3 Chinese version

    SublimeText3 Chinese version

    Chinese version, very easy to use

    Zend Studio 13.0.1

    Zend Studio 13.0.1

    Powerful PHP integrated development environment

    Dreamweaver CS6

    Dreamweaver CS6

    Visual web development tools

    SublimeText3 Mac version

    SublimeText3 Mac version

    God-level code editing software (SublimeText3)

    Square Root in Java Square Root in Java Aug 30, 2024 pm 04:26 PM

    Square Root in Java

    Perfect Number in Java Perfect Number in Java Aug 30, 2024 pm 04:28 PM

    Perfect Number in Java

    Random Number Generator in Java Random Number Generator in Java Aug 30, 2024 pm 04:27 PM

    Random Number Generator in Java

    Armstrong Number in Java Armstrong Number in Java Aug 30, 2024 pm 04:26 PM

    Armstrong Number in Java

    Weka in Java Weka in Java Aug 30, 2024 pm 04:28 PM

    Weka in Java

    Smith Number in Java Smith Number in Java Aug 30, 2024 pm 04:28 PM

    Smith Number in Java

    Java Spring Interview Questions Java Spring Interview Questions Aug 30, 2024 pm 04:29 PM

    Java Spring Interview Questions

    Break or return from Java 8 stream forEach? Break or return from Java 8 stream forEach? Feb 07, 2025 pm 12:09 PM

    Break or return from Java 8 stream forEach?

    See all articles