我知道这似乎是一个非常简单的问题，但是请记住，我是Java新手。附带的是我的源代码，最后写了if语句，如果变量“ valid”为true，则打印出“ Password is valid”。该代码可以正常运行，直到达到这一点为止，此时退出程序而不是打印“ password有效”。我查看了堆栈溢出中的多个线程，以了解如何解决该问题，并且大多数线程建议该代码可以正常工作。任何意见，将不胜感激。谢谢
import java.util.Scanner;
public class PasswordValidator {
public static void main(String[] args) {
//declare name and pass and insert scanner
Scanner sc = new Scanner(System.in);
String name = "name";
String pass = "pass";
// tell user to type name and password and store as variables
System.out.print("Enter user name: ");
name = sc.nextLine();
check(name); // check if name is equal to -1
System.out.print("Enter password: ");
pass = sc.nextLine();
validate(name,pass); // call method
}
static boolean validate(String userName, String password) {
//declare necessary variables
String upperCase = ".*[A-Z].*";
String lowerCase = ".*[a-z].*";
String number = ".*[0-9].*";
String special = ".*[^A-Za-z0-9 ].*";
boolean valid = true;
if (password.matches("-1")) { // if input for password is -1 exit program
System.exit(0);
}
if (password.matches(upperCase)) { // check to see if input has one upper case letter
valid = true;
}
else
System.out.println("Password should contain at least one upper-case alphabet.");
valid = false;
if(password.matches(lowerCase)) { // check to see if input has one lower case letter
valid = true;
}
else
System.out.println("Password should contain at least one lower-case alphabet.");
valid = false;
if (password.matches(number)) { // check to see if input has one number
valid = true;
}
else
System.out.println("Password should contain at least one number.");
valid = false;
if(password.matches(special)) { // check to see if input has a special char.
valid = true;
}
else
System.out.println("Password should contain at least one special character.");
valid = false;
if(password.length()>=7 && password.length() <= 10) { // make sure the password input = 7-10 char.
valid = true;
}
else
System.out.println("Password should be within 7 to 10 characters in length.");
valid = false;
if (password.matches(".*\\s.*")) { // check to see if input has white spaces
System.out.println("Password should not contain whitespace.");
valid = false;
}
if(password.matches(userName)) { // give error if user name and password are the same
System.out.println("Password should not contain or be the same as username.");
valid = false;
}
// this is where I try to print if password is valid. for some reason my program just exits without printing :(
if(valid==true) {
System.out.print("Password is valid");
}
return valid;
}
// method used to check if user name is -1, and close program if so
static boolean check(String userName) {
if (userName.matches("-1")){
System.exit(0);
}
return true;
}
}
答案 0 :(得分：1)
这里的问题是大括号。您在else中打印一些语句，然后不管条件为true还是false，都将有效标志设置为false。另外，最后关闭扫描仪。另外，您无需检查是否valid == true，只需将其置于if条件即可。您的代码看起来像
package com.digit.main;
import java.util.Scanner;
public class PasswordValidator {
public static void main(String[] args) {
// declare name and pass and insert scanner
Scanner sc = new Scanner(System.in);
String name = "name";
String pass = "pass";
// tell user to type name and password and store as variables
System.out.print("Enter user name: ");
name = sc.nextLine();
check(name); // check if name is equal to -1
System.out.print("Enter password: ");
pass = sc.nextLine();
validate(name, pass); // call method
sc.close();
}
static boolean validate(String userName, String password) {
// declare necessary variables
String upperCase = ".*[A-Z].*";
String lowerCase = ".*[a-z].*";
String number = ".*[0-9].*";
String special = ".*[^A-Za-z0-9 ].*";
boolean valid = true;
if (password.matches("-1")) { // if input for password is -1 exit program
System.exit(0);
}
if (password.matches(upperCase)) { // check to see if input has one upper case letter
valid = true;
} else {
System.out.println("Password should contain at least one upper-case alphabet.");
valid = false;
}
if (password.matches(lowerCase)) { // check to see if input has one lower case letter
valid = true;
} else {
System.out.println("Password should contain at least one lower-case alphabet.");
valid = false;
}
if (password.matches(number)) { // check to see if input has one number
valid = true;
} else {
System.out.println("Password should contain at least one number.");
valid = false;
}
if (password.matches(special)) { // check to see if input has a special char.
valid = true;
} else {
System.out.println("Password should contain at least one special character.");
valid = false;
}
if (password.length() >= 7 && password.length() <= 10) { // make sure the password input = 7-10 char.
valid = true;
} else {
System.out.println("Password should be within 7 to 10 characters in length.");
valid = false;
}
if (password.matches(".*\\s.*")) { // check to see if input has white spaces
System.out.println("Password should not contain whitespace.");
valid = false;
}
if (password.matches(userName)) { // give error if user name and password are the same
System.out.println("Password should not contain or be the same as username.");
valid = false;
}
// this is where I try to print if password is valid. for some reason my program
// just exits without printing :(
if (valid) {
System.out.print("Password is valid");
}
return valid;
}
// method used to check if user name is -1, and close program if so
static boolean check(String userName) {
if (userName.matches("-1")) {
System.exit(0);
}
return true;
}
}
答案 1 :(得分：0)
您的module github.com/foo/bar
replace labix.org/v2/mgo => github.com/globalsign/mgo v0.0.0-20181015145952-eeefdecb41b842af6dc652aaea4026e8403e62df
require (
github.com/DATA-DOG/godog v0.7.8
github.com/alecthomas/assert v0.0.0-20170929043011-405dbfeb8e38 // indirect
github.com/alecthomas/colour v0.0.0-20160524082231-60882d9e2721 // indirect
github.com/alecthomas/repr v0.0.0-20181024024818-d37bc2a10ba1 // indirect
...
)
子句不包含括号，因此您多次将else设置为valid。另外，一旦测试失败，您也不想将false设置回valid。解决这两个问题应该会给您带来类似的效果，
true答案 2 :(得分：0)
您应该将所有uploadImage=(e)=>{
let file = e.target.files[0];
if (file && !file.name) {
window.alert("Please select a file");
return false;
}
if (file.size > 10e6) {
window.alert("Please upload a file smaller than 10 MB");
return false;
}
}
部件都放在方括号内，
例如：
代替使用此
else请像这样使用它
else
System.out.println("Password should be within 7 to 10 characters in length.");
valid = false;
您应该对所有else
{
System.out.println("Password should be within 7 to 10 characters in length.");
valid = false;
}
部分执行此操作，并且应该可以使用。
如果使用不带方括号的else，则仅else之后的第一行将位于else之内。那就是您在这里所做的错误。此外，如果您仔细了解了代码的执行方式，则可以通过始终删除不必要的false和true分配来改进代码