线程"main"中出现异常java.lang.IndexOutOfBoundsException:无组1

您需要在正则表达式中添加捕获组.这是通过将您想要捕获的内容放在括号中来完成的:

Pattern pattern = Pattern.compile("(.*):.*"); // <-- parentheses here
String  name = "abc:def";
Matcher matcher = pattern.matcher(name);

if (matcher.find()) {
    String group = matcher.group(1);
    System.out.println(group); // prints "abc"
}