Java 匹配器结果-正则表达式

有没有办法知道Matcher出了什么问题？在这种情况下，不允许使用“！”，从正则表达式中可以看到。我想知道一个结果，类似“

”！”的内容是不允许的

”

您可以先测试正则表达式是否匹配（使用函数没有理由添加

^

和

$

），然后如果不匹配，您可以处理一些可能的情况：

final String regex = "^[A-Za-z0-9]{1,12}$";
final Pattern pattern = Pattern.compile(regex);

System.out.println(pattern.matcher("hi!").?);

---

您可以根据模式将所有字符替换为

“

，这将为您提供不允许的字符。然而，这里有一个陷阱：我使用的模式没有行的开头（

^

）和行的结尾（

$

），这是我将考虑和更新的内容

演示：

public void complianceCheck(String inputString) {
    final String regex = "[A-Za-z0-9]{1,12}";
    
    if (!Pattern.compile(regex).matcher(inputString).matches()) {
        Matcher matcher = Pattern.compile(regex).matcher(inputString);
        if (matcher.find()) {
            String match = matcher.group(0);
            if (Pattern.compile("^" + regex).matcher(inputString).find())
                System.out.printf("'%s' shouldn't be followed by '%s'\n", match, inputString.replaceFirst("^" + regex, ""));
            else if (Pattern.compile(regex + "$").matcher(inputString).find())
                System.out.printf("'%s' shouldn't be preceded by '%s'\n", match, inputString.replaceFirst(regex + "$", ""));
            else
                System.out.printf("%s shouldn't be between something else\n", match);
        }
        else System.out.println("No match");
    }
    else System.out.println("OK");
}

@Test
public void test() {
    complianceCheck("hi!");    // this will print "'hi' shouldn't be followed by '!'"
    complianceCheck("...hi");  // this will print "'hi' shouldn't be preceded by '...'"
    complianceCheck("...hi!"); // this will print "'hi' shouldn't be between something else"
    complianceCheck("...");    // this will print "No match"
    complianceCheck("hi");     // this will print "OK"
}

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        final String regex = "[A-Za-z0-9]{1,12}";

        String str = "hi!&";

        String remaining = str.replaceAll(regex, "");

        System.out.println("The following characters are not allowed: " + Arrays.toString(remaining.split("")));
    }
}

输出：

public void complianceCheck(String inputString) {
    final String regex = "[A-Za-z0-9]{1,12}";
    
    if (!Pattern.compile(regex).matcher(inputString).matches()) {
        Matcher matcher = Pattern.compile(regex).matcher(inputString);
        if (matcher.find()) {
            String match = matcher.group(0);
            if (Pattern.compile("^" + regex).matcher(inputString).find())
                System.out.printf("'%s' shouldn't be followed by '%s'\n", match, inputString.replaceFirst("^" + regex, ""));
            else if (Pattern.compile(regex + "$").matcher(inputString).find())
                System.out.printf("'%s' shouldn't be preceded by '%s'\n", match, inputString.replaceFirst(regex + "$", ""));
            else
                System.out.printf("%s shouldn't be between something else\n", match);
        }
        else System.out.println("No match");
    }
    else System.out.println("OK");
}

@Test
public void test() {
    complianceCheck("hi!");    // this will print "'hi' shouldn't be followed by '!'"
    complianceCheck("...hi");  // this will print "'hi' shouldn't be preceded by '...'"
    complianceCheck("...hi!"); // this will print "'hi' shouldn't be between something else"
    complianceCheck("...");    // this will print "No match"
    complianceCheck("hi");     // this will print "OK"
}

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        final String regex = "[A-Za-z0-9]{1,12}";

        String str = "hi!&";

        String remaining = str.replaceAll(regex, "");

        System.out.println("The following characters are not allowed: " + Arrays.toString(remaining.split("")));
    }
}

---

正则表达式正在匹配由一组有限字符组成的任何字符串，并且具有最大长度

您可以通过其他方式轻松检查长度。对于不匹配的字符，只需测试相反的字符

publicstaticvoidmain（字符串[]args）抛出java.lang.Exception
{
System.out.println（test（“hello！”）；
System.out.println（test（“hello”）；
}
公共静态布尔测试（字符串输入）{
if（input.length（）<1）{
System.err.println（“太短”）；
返回false；
}
if（input.length（）>12）{
System.err.println（“太长”）；
返回false；
}
最终模式=模式。编译（“[^A-Za-z0-9]”）；
匹配器m=模式匹配器（输入）；
布尔拒绝=假；
while（m.find（））{
System.err.println（m.group（0）+“不允许！”）；
拒绝=正确；
}
返回！拒绝；
}

问题是针对任何正则表达式还是仅针对此特定正则表达式？