如何在Java中将下划线转换成易于理解的名称？

Question

I'd like to write a method that converts CamelCase into a human-readable name. This is very similar to this question but now with underscore.

Here's the test case:

public void testSplitUnderscore() {
    assertEquals("lowercase", splitUnderscore("lowercase"));
    assertEquals("Class", splitUnderscore("Class"));
    assertEquals("My Class", splitUnderscore("My_Class"));
    assertEquals("HTML", splitUnderscore("HTML"));
    assertEquals("PDF Loader", splitUnderscore("PDF_Loader"));
    assertEquals("A String", splitUnderscore("A_String"));
    assertEquals("Simple XML Parser", splitUnderscore("Simple_XML_Parser"));
    assertEquals("GL 11 Version", splitUnderscore("GL_11_Version"));
    assertEquals("99 Bottles", splitUnderscore("99_Bottle"));
    assertEquals("May 5", splitUnderscore("May_5"));
    assertEquals("BFG 9000", splitUnderscore("BFG_9000"));
    assertEquals("beginning", splitUnderscore("_beginning"));
    assertEquals("end", splitUnderscore("end_"));
    assertEquals("double middle", splitUnderscore("double__middle"));
    assertEquals("double end", splitUnderscore("double_end__"));
    assertEquals("double start", splitUnderscore("__double_start"));
    assertEquals("double start middle end", splitUnderscore("__double_start__middle_end__"));
}

Answer 1

A naive way of accomplishing this would be to replace every '_' with a ' ' , and then trim the whitespaces off the final string:

public static String splitUnderscore(String s) {
    return s.replace("_", " ").trim();
}

While the above works for most cases, to handle multiple adjacent underscores we could use a regular expression to replace any number of consecutive underscores with a single ' ' :

public static String splitUnderscore(String s) {
    return s.replaceAll("_{1,}", " ").trim();
}

Answer 2

以下应该工作：

String.replace('_', " ").trim();

Answer 3

You should have a couple more test cases:

assertEquals("A String", splitUnderscore("double__middle"));
assertEquals("A String", splitUnderscore("double_end__"));
assertEquals("A String", splitUnderscore("__double_start"));
assertEquals("A String", splitUnderscore("__double_start__middle_end__"));