为什么此正则表达式无法在java / kotlin中运行：[0-9] + km \ / h

Question

我有我的正则表达式模式：[0-9]+ km\/h

这是我的测试字符串：Northernly winds 10 to 20 km/h decreasing to 5 to 10 km/h in the afternoon.

此模式适用于在线正则表达式测试器工具，但是在下面的代码中失败：

  val description = "Northernly winds 10 to 20 km/h decreasing to 5 to 10 km/h in the afternoon."
  val pattern = Pattern.compile("[0-9]+ km/h")
  val matcher = pattern.matcher(description)
  return matcher.matches() // returns false :(

matcher.matches()返回假的原因是什么？

Answer 1

下面经过修改的java程序可以与提供的正则表达式一起正常工作

 String description = "Northernly winds 10 to 20 km/h decreasing to 5 to 10 km/h in the afternoon.";
Pattern pattern = Pattern.compile("[0-9]+ km/h");
Matcher matcher = pattern.matcher(description);
System.out.println( matcher.find());

下面的代码说明何时可以使用matchs函数，匹配项将搜索整个单词。

 String description = "20 km/h";
Pattern pattern = Pattern.compile("[0-9]+ km/h");
Matcher matcher = pattern.matcher(description);
System.out.println( matcher.matches());