接受字符串的扫描程序输入会跳过while循环内的所有其他输入。

Question

好的，代码很简单。包含一些元素的通用类ourSet将其放入LinkedList中，并对这两个集合执行某些功能。

我的问题实际上与项目的总体概念无关，更多的是在我创建的“用户输入界面”中。我希望它接受一些字符串并将其添加到集合中，然后在接收字符串“
EXIT”（全部大写）的同时退出循环，并对下一个集合进行相同的操作。发生的事情是do while循环仅发送所有奇数的1st，3rd，5th..。

package set.pkgclass;

import java.util.Scanner; 
import java.util.LinkedList;


public class SetClass {


public static void main(String[] args) {

    ourSet<String> set1 = new ourSet<String>();  
    ourSet<String> set2 = new ourSet<String>(); 
    Scanner input = new Scanner(System.in);



    System.out.println("Please enter a string to put in set 1, "
            + "type EXIT (in all caps) to end.");


    do {

        set1.add(input.nextLine());

    }
    while (!"EXIT".equals(input.nextLine()));


    System.out.println("Please enter a string to put in set 2, "
            + "type EXIT (in all caps) to end");

    do {

        set2.add(input.nextLine());
    }
    while (!"EXIT".equals(input.nextLine()));



    ourSet.intersection(set1,set2); 
    ourSet.difference(set1, set2);
    ourSet.union(set1, set2);








     }
  }

class ourSet<T>{




private LinkedList<T> mySet = new LinkedList<>();



public void add(T element){      
    mySet.add(element);
}

public void remove(T element){        
    mySet.remove(element);
}

public boolean membership(T element){        
    if(mySet.contains(element) == true) {
        return true; 
    }

    else {
    return false;
    }
}


public static <T> void union(ourSet<T> s1, ourSet<T> s2){
    System.out.print("The union is: ");
    for (int i=0; i < s1.mySet.size(); i++) {
        T t = s1.mySet.get(i);
        if (!s2.mySet.contains(t)){
            s2.add(t);
            }

    }

    for (int i=0; i < s2.mySet.size(); i++){
        T t = s2.mySet.get(i);
        System.out.print(t+", ");
    }
    System.out.println();


}
public static <T> void intersection(ourSet<T> s1, ourSet<T> s2){ 
    System.out.print("The intersection is: ");
    for (int i=0; i < s1.mySet.size(); i++) {
        T t = s1.mySet.get(i); 
        if (s2.mySet.contains(t)) {
            System.out.print(t+", ");
        }
    }
    System.out.println();

}

public static <T> void difference(ourSet<T> s1, ourSet<T> s2){
    System.out.print("The difference is: ");
    for (int i=0; i < s1.mySet.size(); i++) {
        T t = s1.mySet.get(i);
        if (!s2.mySet.contains(t)) {
            System.out.print(t+", ");
        }

    }
    System.out.println();  
   }
 }

Answer 1

原因是，您打了input.nextLine() 两次 电话：

do {

    set1.add(input.nextLine());

}
while (!"EXIT".equals(input.nextLine()));

比do-while更容易的方法是while：

while (!(String in = input.nextLine()).equals("EXIT")) {
    set1.add(in);
}