Question 4.11: Write a Java method to check whether a string is a valid password.
Password rules:
A password must have at least ten characters.
A password consists of only letters and digits.
A password must contain at least two digits.
Expected Output:
1. A password must have at least eight characters.
2. A password consists of only letters and digits.
3. A password must contain at least two digits
Input a password (You are agreeing to the above Terms and Conditions.): abcd1234
Password is valid: abcd1234
Solution:
package lab4problem11;
import java.util.Scanner;
public class Lab4Problem11 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in); System.out.print("1. A password must have at least eight characters.\n" + "2. A password consists of only letters and digits.\n" + "3. A password must contain at least two digits \n" + "Input a password (You are agreeing to the above Terms and Conditions.): "); String number = input.nextLine(); if (isValidPassword(number)) { System.out.println("Password is valid: " + number); } else { System.out.println("Not a valid password: " + number); } } public static boolean isValidPassword(String password) { if (password.length() < 8) return false; int charCount = 0; int numCount = 0; for (int i = 0; i < password.length(); i++) { char ch = password.charAt(i); if (isNumeric(ch)) { numCount++; } else if (isLetter(ch)) { charCount++; } else { return false; } } return (charCount >= 2 && numCount >= 2); } public static boolean isLetter(char ch) { ch = Character.toUpperCase(ch); return (ch >= 'A' && ch <= 'Z'); } public static boolean isNumeric(char ch) { return (ch >= '0' && ch <= '9'); }}
package lab4problem11;
import java.util.Scanner;
public class Lab4Problem11 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("1. A password must have at least eight characters.\n" +
"2. A password consists of only letters and digits.\n" +
"3. A password must contain at least two digits \n" +
"Input a password (You are agreeing to the above Terms and Conditions.): ");
String number = input.nextLine();
if (isValidPassword(number)) {
System.out.println("Password is valid: " + number);
} else {
System.out.println("Not a valid password: " + number);
}
}
public static boolean isValidPassword(String password) {
if (password.length() < 8)
return false;
int charCount = 0;
int numCount = 0;
for (int i = 0; i < password.length(); i++) {
char ch = password.charAt(i);
if (isNumeric(ch)) {
numCount++;
} else if (isLetter(ch)) {
charCount++;
} else {
return false;
}
}
return (charCount >= 2 && numCount >= 2);
}
public static boolean isLetter(char ch) {
ch = Character.toUpperCase(ch);
return (ch >= 'A' && ch <= 'Z');
}
public static boolean isNumeric(char ch) {
return (ch >= '0' && ch <= '9');
}
}
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