java 怎么在控制台把换行符打印出来？

Question

在windows环境下

    public static void main(String[] args) {
        String b = String.format("The data download task succeed. %nName:%s ", "1");

        System.out.println(b);
        String a = "The data download task succeed. \r\n" +
                "Name:1 ";
        System.out.println(a);
        System.out.println(a.equals(b));
    }

运行结果为

The data download task succeed. 
Name:1 
The data download task succeed. 
Name:1 
true

有没有方式可以在控制台不格式化显示，而把原样的换行符打印出来，类似下面这样

The data download task succeed. \r\n Name:1 

Answer 1

public static void main(String[] args) {
    String b = String.format("The data download task succeed. %nName:%s ", "1");
    printWithEscapeSequences(b);

    String a = "The data download task succeed. \r\n" +
            "Name:1 ";
    printWithEscapeSequences(a);

    System.out.println(a.equals(b));
}

public static void printWithEscapeSequences(String str) {
    String replaced = str.replace("\r", "\\r").replace("\n", "\\n");
    System.out.println(replaced);
}

Answer 2

不改代码就只能替换System.out了，java io 的 api 都可以这么套娃操作（装饰器模式）

    public static void main(String[] args) {
        String testText = "xxx\r\n";
        System.out.println(testText);

        // 获取当前的 out
        PrintStream oldOut = System.out;

        // 在当前的 out 上包装一层，将输出内容里的特殊字符进行替换
        PrintStream newOut = new PrintStream(oldOut) {
            @Override
            public void println(String x) {
                String s = x;
                if (s != null) {
                    s = s.replaceAll("\n", "\\\\n");
                    s = s.replaceAll("\r", "\\\\r");
                }
                super.println(s);
            }
        };

        // 设置新 out
        System.setOut(newOut);

        System.out.println(testText);
    }

Answer 3

转义'\'

 String a = "The data download task succeed. \\r\\n" +
                "Name:1 ";

Answer 4

通过控制台打印来看分割符是不可靠的。可以直接通过System.lineSeparator()来获取当前操作系统的换行符，然后在代码里针对不同操作系统进行特定的处理。