Java – exception in stackoverflow error of thread “main”

I am writing a program to verify whether the password meets the corresponding requirements I've written all the code and I think it should work, but I received the following error:

Exception in thread "main" java.lang.StackOverflowError
at java.lang.String.length(String.java:623)
at PasswordVerifier.isValid(PasswordVerifier.java:5)
at PasswordVerifier.isValid(PasswordVerifier.java:6)

Then it repeats the last line of the error for a long time I've been looking around as if I couldn't figure out my problem I know something is constantly circulating. I don't want to, but the repair is not on me This is my code

public class PasswordVerifier{
  private static int MIN_PASSWORD_LENGTH = 6;

  public static boolean isValid(String str){
     if (str.length() >= MIN_PASSWORD_LENGTH){
        if (PasswordVerifier.isValid(str) == true){
           if (PasswordVerifier.hasUpperCase(str) == true){
              if (PasswordVerifier.hasLowerCase(str) == true){
                 if (PasswordVerifier.hasDigit(str) == true){
                    return true;
                 }
              }
           }
        }
     }
        return false;
  }

  private static boolean hasUpperCase(String str){
     for (char c : str.tocharArray()){
        if (Character.isUpperCase(c)){
           return true;
        }
     }
     return false;
  }

  private static boolean hasLowerCase(String str){
     for (char c : str.tocharArray()){
        if (Character.isLowerCase(c)){
           return true;
        }
     }
     return false;
  }

  private static boolean hasDigit(String str){
     for (char c : str.tocharArray()){
        if (Character.isDigit(c)){
           return true;
        }
     }
     return false;
  }
 }

Any help will be greatly appreciated!

Solution

public static boolean isValid(String str){

public static boolean isValid(String str){
    // ...
        if (PasswordVerifier.isValid(str) == true){
        // ...
        }
    // ...
}

You call isvalid (string) internally, which results in infinite loop recursion

I'll guess and say that's what you want:

public static boolean isValid(String str){
    if (str.length() >= MIN_PASSWORD_LENGTH){
        // Removed call to .isValid(String)
        if (PasswordVerifier.hasUpperCase(str)){
            if (PasswordVerifier.hasLowerCase(str)){
                if (PasswordVerifier.hasDigit(str)){
                    return true;
                }
            }
        }
    }
    return false;
}