java - 無限の while ループが原因で Java が NoSuchElementException をスローする

Question

システムの終了は、プログラムの最後に到達したときに発生しますが、内側の while ループと同じように機能するはずです。どんな提案でも大歓迎です。これが私が得るエラーメッセージです：

Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:907)
at java.util.Scanner.next(Scanner.java:1530)
at java.util.Scanner.nextInt(Scanner.java:2160)
at java.util.Scanner.nextInt(Scanner.java:2119)
at beast.main(beast.java:75)

これが私のコードです

while(loopkey==1){//Call Methods and enables user to pick another exercise
    UserManual();
    System.out.print("Input the topickey here: ");//prompts for topic
    int topickey=kbd.nextInt();//scans topickey(which is an int)

    if(topickey==1)DoAdditionEx(j);//does addition
    else if(topickey==2)DoSubtractionEx(j);//does subtraction
    else if(topickey==3)DoMultiplicationEx(j);//does multiplication
    else{
        int errorkey=1;
        while(errorkey==1){
            System.out.print("ERROR: COMMAND NOT RECONGISED\nPlease reselect your topic of interest: ");
            topickey=kbd.nextInt();
            if(topickey==1 || topickey==2 || topickey==3) errorkey=0;
        }
    }
    if(topickey==1)DoAdditionEx(j);//does addition
    else if(topickey==2)DoSubtractionEx(j);//does subtraction
    else if(topickey==3)DoMultiplicationEx(j);//does multiplication

    System.out.println("Would you like to continue practicing? Please enter '1' for yes or '0' for no.");
    System.out.print("Input your choice here: ");

    int multitopickey=kbd.nextInt();
    if(multitopickey!=1) loopkey=0;
}