Question

请参阅以下代码

    String line = "abc_dfgb_tf";

    String pattern1 = "(\\w+)([+-])(\\d+)(\\w+)";
    Pattern r1 = Pattern.compile(pattern1);
    Matcher m1 = r1.matcher(line);

    if (m1.find( )) 
    {
       System.out.println("Found value: " + m1.group(1) );
       System.out.println("Found value: " + m1.group(2) );
       System.out.println("Found value: " + m1.group(3) );
       System.out.println("Found value: " + m1.group(4) );
    }

如果是“abc_dfgb_tf”，则字符串m1.find（）将变为false。

请建议用于两种类型字符串“abc_dfgb_tf”和“abc_dfgb_tf + 1cbv”的模式

帮助

Answer 1

你似乎想要这样的东西：

String pattern1 = "(\\w+)(?:([+-])(\\d+)(\\w+))?";

这使得可选尾部实际上是可选的。

Answer 2

您似乎想要除第一组以外的可选所有内容。像

这样的东西

String line = "abc_dfgb_tf";
String pattern1 = "(\\w+)([+-]*)(\\d*)(\\w*)";
Pattern r1 = Pattern.compile(pattern1);
Matcher m1 = r1.matcher(line);

if (m1.find()) {
    System.out.println("Found value: " + m1.group(1));
    System.out.println("Found value: " + m1.group(2));
    System.out.println("Found value: " + m1.group(3));
    System.out.println("Found value: " + m1.group(4));
}

输出

Found value: abc_dfgb_tf
Found value: 
Found value: 
Found value:

如果我将行更改为String line = "abc_dfgb_tf+1cbv";输出

Found value: abc_dfgb_tf
Found value: +
Found value: 1
Found value: cbv

如何在java中使用模式查找字符串

2 个答案: