我制作了一个简单的程序，可以选择添加，投票和查看3个不同候选人的投票。由于某种原因，第18行重复自身和它后面的第72行，例如，如果你开始，按1创建候选人，输入名称并按回车，它将通过这样：
Add candidate (1) or vote (2) or view number of votes on each candidate (3): Incorrect number, please try again.
然后又恢复正常......
Add candidate (1) or vote (2) or view number of votes on each candidate (3):
以下是整个代码（注明重复行）：
package array;
import java.util.Scanner;
public class Array {
public static void main(String[] args) {
char[] Vote_Choice = {'A', 'B', 'C'};
String[] candidates = { "none", "none", "none"};
int[] votes = {0, 0, 0};
Scanner input = new Scanner(System.in);
boolean done = false;
while (!done) {
boolean done2 = false;
System.out.print("Add candidate (1) or vote (2) or view number of votes on each candidate (3): "); // here (line 18)
switch (input.nextLine()) {
case "1": System.out.print("Type new candidates name: ");
while (!done2) {
if (candidates[0].equals("none")) {
candidates[0] = input.next();
done2 = true;
}
else if (!candidates[0].equals("none") && candidates[1].equals("none")) {
candidates[1] = input.next();
done2 = true;
}
else if (!candidates[0].equals("none") && !candidates[1].equals("none") && candidates[2].equals("none")) {
candidates[2] = input.next();
done2 = true;
}
else if (!candidates[0].equals("none") && !candidates[1].equals("none") && !candidates[2].equals("none")) {
System.out.println("Sorry, all candidate slots are full.");
done2 = true;
}
}
break;
case "2":
System.out.println("Type letter corresponding to the candidate you wish to vote for: ");
System.out.print("Type A for candidate "+ candidates[0] +", type B for candidate "+candidates[1]+", type C for candidate "+candidates[2]+": ");
String choice = input.next();
if (choice.equals("A")) {
votes[0]++;
}
if (choice.equals("B")) {
votes[1]++;
}
if (choice.equals("C")) {
votes[2]++;
}
break;
case "3": if (!candidates[0].equals("none")) {
System.out.println("Candidate "+ candidates[0] +": "+votes[0]);
}
if (!candidates[1].equals("none")) {
System.out.println("Candidate "+ candidates[1] +": "+votes[1]);
}
if (!candidates[2].equals("none")) {
System.out.println("Candidate "+ candidates[2] +": "+votes[2]);
}
else {
System.out.println("Sorry, there are no current candidates.");
}
break;
default: System.out.println("Incorrect number, please try again."); // And here, line 72
}
}
}
}
答案 0 :(得分：1)
这是因为您有input.next()而不是input.nextLine()。线路终点＆＃34;停留＆＃34;在输入流中，当你调用它时，它返回该流中剩下的内容（通常是空字符串）。
答案 1 :(得分：0)
致电时：
candidates[1] = input.next();
这导致了问题，因为它只消耗部分输入。
如果您认为来自键盘的输入流可能类似于： 1 \ nDavid \ n
正在发生的事情是你正在阅读＆＃34; 1 \ n＆＃34;当你读到这一行时，那么当你读到＆＃34; next＆＃34;你读了＃34; David＆＃34;，而不是新的行字符，所以下次调用nextLine时，你会得到空行，从\ n开始（\ n是一个新的行字符）。
您的代码应为：
import java.util.Scanner;
public class Array {
public static void main(String[] args) {
char[] Vote_Choice = { 'A', 'B', 'C' };
String[] candidates = { "none", "none", "none" };
int[] votes = { 0, 0, 0 };
Scanner input = new Scanner(System.in);
boolean done = false;
while (!done) {
boolean done2 = false;
System.out
.print("Add candidate (1) or vote (2) or view number of votes on each candidate (3): "); // here
// (line
// 18)
switch (input.nextLine()) {
case "1":
System.out.print("Type new candidates name: ");
while (!done2) {
if (candidates[0].equals("none")) {
candidates[0] = input.nextLine();
done2 = true;
} else if (!candidates[0].equals("none")
&& candidates[1].equals("none")) {
candidates[1] = input.nextLine();
done2 = true;
} else if (!candidates[0].equals("none")
&& !candidates[1].equals("none")
&& candidates[2].equals("none")) {
candidates[2] = input.nextLine();
done2 = true;
} else if (!candidates[0].equals("none")
&& !candidates[1].equals("none")
&& !candidates[2].equals("none")) {
System.out
.println("Sorry, all candidate slots are full.");
done2 = true;
}
}
break;
case "2":
System.out
.println("Type letter corresponding to the candidate you wish to vote for: ");
System.out.print("Type A for candidate " + candidates[0]
+ ", type B for candidate " + candidates[1]
+ ", type C for candidate " + candidates[2] + ": ");
String choice = input.nextLine();
if (choice.equals("A")) {
votes[0]++;
}
if (choice.equals("B")) {
votes[1]++;
}
if (choice.equals("C")) {
votes[2]++;
}
break;
case "3":
if (!candidates[0].equals("none")) {
System.out.println("Candidate " + candidates[0] + ": "
+ votes[0]);
}
if (!candidates[1].equals("none")) {
System.out.println("Candidate " + candidates[1] + ": "
+ votes[1]);
}
if (!candidates[2].equals("none")) {
System.out.println("Candidate " + candidates[2] + ": "
+ votes[2]);
} else {
System.out
.println("Sorry, there are no current candidates.");
}
break;
default:
System.out.println("Incorrect number, please try again."); // And
// here,
// line
// 72
}
}
}
}