突破用户输入的while循环

Question

I have this code:

import java.util.*;

class Uke44{
    public static void main(String[]args){

    Scanner input=new Scanner(System.in);
    boolean lokke=true;

    System.out.println("Vennligst oppgi navn: ");
    String navn=input.nextLine();

    while(lokke){

    for(int i=0; i<100; i++){
        System.out.println(navn);
    }

    System.out.println("Gi et nytt navn? j/n: ");
    char valg = input.next().charAt(0);

    if(valg.contains("j")){
        lokke=true;
        System.out.println("Skriv et nytt navn: ");
        navn=input.nextLine();

    }else{
        lokke=false;
    }
    }
    }
}

And what I want it to do is that when the user inputs: j at prompt, it should just reenact the lokke-variable to true, the loop runs again and the user is prompted to put in j or n for whether or not he/she wants to continue the program. But the valg.contains("j")) doesn't work. Before I have always needed to save the possible choices in their own variables, and then use the "=="-operator to make the program check for equality. But is there an easier way? Like, equalto or something?

Answer 1

char是原始数字类型，因此您需要将代码更改为if(valg == 'j') ，它将起作用

Answer 2

valg is not a String , it's a char . A char isn't an Object, it's a primitive, therefore it has no functionality.

A char is also only a single character, ever, therefore it makes no sense to even provide contains , either it is or it's not...

Try using something like...

if(valg == 'j')){

...instead

Answer 3

import java.util.*;

class Uke44{
    public static void main(String[]args){

    Scanner input=new Scanner(System.in);
    boolean lokke=true;

    System.out.println("Vennligst oppgi navn: ");
    String navn=input.nextLine();

    while(lokke)
    {

    for(int i=0; i<2; i++)
        System.out.println(navn);


    System.out.println("Gi et nytt navn? j/n: ");
    char valg = input.next().charAt(0);
    System.out.println(valg);

    if(valg=='j')
    {
        lokke=true;
        System.out.println("Skriv et nytt navn: ");
        Scanner input1=new Scanner(System.in);
        navn=input1.nextLine();



    }
    else
        lokke=false;

    } 
    }
}

this is the correct code .

and basically the changed part :

 if(valg=='j')
    {
        lokke=true;
        System.out.println("Skriv et nytt navn: ");
        Scanner input1=new Scanner(System.in);
        navn=input1.nextLine();