Question

import java.util.Scanner;

public class App {

  public static void main(String[] args) {

    System.out.println("Please enter your official name.");

    Scanner typing = new Scanner(System.in);
    String name = typing.nextLine();

    while (!name.matches("[a-zA-Z]")) {
      System.out.println("Please enter your official name.");
      name = typing.nextLine();
    }
    if (name.length() >= 4)
      System.out.println("Your name is: " + name);

    else
      System.out.println("So your name is less than four characters.");

  }

}

如何在此处重新启动程序！ PS：是Java的初学者

Answer 1

一旦main方法退出，应用程序就会退出。将您的代码放入另一个方法中，并在while循环中调用它。

public static void main(String[] args) {
    while(true){
        process();
    }
}

static void process(){
    System.out.println("Please enter your official name.");

    Scanner typing = new Scanner(System.in);
    String name = typing.nextLine();

    while (!name.matches("[a-zA-Z]")) {
      System.out.println("Please enter your official name.");
      name = typing.nextLine();
    }
    if (name.length() >= 4)
      System.out.println("Your name is: " + name);

    else
      System.out.println("So your name is less than four characters.");
}

这将无限次地运行程序。如果要退出，请按cmd中的 Ctrl + C 或可以使用

System.exit(0);

代码中的某个地方。

Answer 2

要完全重新启动该程序并不容易，而且也不是必需的。您可以用另一种方式做同样的事情。

public static void main(String[] args) {
    foo();
}

public static void foo(){
    System.out.println("Please enter your official name.");

    Scanner typing = new Scanner(System.in);
    String name = typing.nextLine();

    while (!name.matches("[a-zA-Z]")) {
        System.out.println("Please enter your official name.");
        name = typing.nextLine();
    }
    if (name.length() >= 4)
        System.out.println("Your name is: " + name);

    else
        System.out.println("So your name is less than four characters.");

    if(true){// put your condition when you what to restart here
        foo();// rerun this method
    }
}

更新。长时间运行后，以前的解决方案可能会导致错误。这样更好。

public static void main(String[] args) {
    boolean willContinue = false;
    do{
        System.out.println("Please enter your official name.");

        Scanner typing = new Scanner(System.in);
        String name = typing.nextLine();

        while (!name.matches("[a-zA-Z]")) {
            System.out.println("Please enter your official name.");
            name = typing.nextLine();
        }
        if (name.length() >= 4)
            System.out.println("Your name is: " + name);

        else
            System.out.println("So your name is less than four characters.");

        willContinue = true;// put your condition when you what to restart here
    }while(willContinue);
}

Answer 3

非常感谢大家，从两个答案中汲取了教训并写下了这段话：

导入java.util.Scanner;

公共类应用{

public static void main(String[] args) {
    restart();

}

public static void restart() {
    System.out.println("Please enter your official name!");
    Scanner input = new Scanner(System.in);
    String name = input.nextLine();
    String regex = "^[a-zA-Z]+$";

    do {
        System.out.println("Please enter your official name.");
        name = input.nextLine();

    } while (name.length() < 11);

    if (name.matches(regex)) {
        System.out.println("Your name is: " + name);
        System.exit(0);
    }

    else {
        System.out.println("That's not a name!");
        restart();
    }

}

}

Answer 4

我进一步改进了它：

导入java.util.Scanner;

公共类应用{

public static void main(String[] args) {
    restart();

}

public static void restart() {
    System.out.println("Please enter your official name!");
    Scanner input = new Scanner(System.in);
    String name = input.nextLine();
    String regex = "^[a-zA-Z]+$";

    while (name.length() < 11) {
        System.out.println("Please enter your official name.");
        name = input.nextLine();
        continue;
    }

    if (name.matches(regex)) {
        System.out.println("Your name is: " + name);
        System.exit(0);
    }

    else {
        System.out.println("That's not a name!");
        restart();
    }

}

}

如何在这里重新启动Java程序

4 个答案: