System.lineSeparator（）什么都不返回 [英] System.lineSeparator() returns nothing

问题描述

使用以下内容时应该看到什么？

What should I see when I use the following?

System.out.println("LineSeperator1: "+System.getProperty("line.separator"));
System.out.println("LineSeperator2: "+System.lineSeparator());

我得到以下回报：

LineSeperator1: 

LineSeperator2: 

它是空的吗？无形？应该有类似 \ r或\ n 的东西？

Is it empty? invisible? shouldn there be something like \r or \n?

我使用的是Windows 7，eclipse和jdk 1.8 。

I use windows 7, eclipse and jdk 1.8.

推荐答案

正如您所料，行分隔符包含特殊字符，例如'\ r'或'\ n'表示一行的结尾。但是，尽管它们将使用那些反斜杠转义序列用Java源代码编写，但它们在打印时不会出现这种情况。行分隔符的目的是分隔行，例如，

As you expect, the line separator contains special characters such as '\r' or '\n' that denote the end of a line. However, although they would be written in Java source code with those backslash escape sequences, they do not appear that way when printed. The purpose of a line separator is to separate lines, so, for example, the output of

System.out.println("Hello"+System.lineSeparator()+"World");

Hello
World

而不是说

Hello\nWorld

你甚至可以在你的代码输出中看到这个：输出

You can even see this in the output of your code: the output of

System.out.println("LineSeperator1: "+System.getProperty("line.separator"));

在下一个语句的输出之前有一个额外的空行，因为有一个行分隔符来自 System.getProperty（line.separator）和另一个使用 println 。

had an extra blank line before the output of the next statement, because there was a line separator from System.getProperty("line.separator") and another from the use of println.

如果你真的想看看行分隔符的转义版本是什么样的，你可以使用 escapeJava来自 Apache Commons 的 。例如：

If you really want to see what the escaped versions of the line separators look like, you can use escapeJava from Apache Commons. For example:

import org.apache.commons.lang3.StringEscapeUtils;

public class LineSeparators {
    public static void main(String[] args) {
        String ls1 = StringEscapeUtils.escapeJava(System.getProperty("line.separator"));
        System.out.println("LineSeperator1: "+ls1);
        String ls2 = StringEscapeUtils.escapeJava(System.lineSeparator());
        System.out.println("LineSeperator2: "+ls2);
    }
}

在我的系统上，输出

LineSeparator1: \n
LineSeparator2: \n

请注意，我必须在与 Apache下载，使用这些命令进行编译和运行

Note that I had to run it in the same folder as the .jar file from the Apache download, compiling and running with these commands

javac -cp commons-lang3-3.4.jar LineSeparators.java
java -cp commons-lang3-3.4.jar:. LineSeparators

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