英文:
While loop nested if else java
问题
public class QuizW
{
public static void main(String[] args)
{
String question = "What is the capital of Australia? \n";
question += "A. Sydney\n";
question += "B. Melbourne\n";
question += "C. Perth\n";
question += "D. Canberra\n";
question += "E. Brisbane\n";
String answer = JOptionPane.showInputDialog(question);
answer = answer.toUpperCase();
int answerCorrect = 0;
while (answerCorrect == 0)
{
if (answer.equals("D"))
{
JOptionPane.showMessageDialog(null, "Correct!");
break;
}
else if (answer.equals("A") || answer.equals("B") || answer.equals("C") || answer.equals("E"))
{
JOptionPane.showMessageDialog(null, "Incorrect. Please try again.");
}
else
{
JOptionPane.showMessageDialog(null, "Invalid answer. Please enter A, B, C, D, or E.");
}
JOptionPane.showInputDialog(question);
}
}
}
英文:
I have a problem with my while loop. It needs to keep asking the question until the answer is correct. Can someone please advise?
public class QuizW
{
public static void main(String[] args)
{
String question = "What is the capital of Australia? \n";
question += "A. Sydney\n";
question += "B. Melburne\n";
question += "C. Perth\n";
question += "D. Cannberra\n";
question += "E. Brisbane\n";
String answer = JOptionPane.showInputDialog(question);
answer = answer.toUpperCase();
int answerCorrect = 0;
while (answerCorrect == 0)
{
if (answer.equals("D"))
{
JOptionPane.showMessageDialog(null, "Correct!");
break;
}
else if (answer.equals("A") || answer.equals("B") || answer.equals("C") || answer.equals("E"))
{
JOptionPane.showMessageDialog(null, "Incorrect. Please try again.");
}
else
{
JOptionPane.showMessageDialog(null, "Invalid answer. Please enter A, B, C, D, or E.");
}
JOptionPane.showInputDialog(question);
}
}
}
答案1
得分: 1
你可以这样做：
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String question = "澳大利亚的首都是哪里？ \n"
+ "A. 悉尼\n"
+ "B. 墨尔本\n"
+ "C. 珀斯\n"
+ "D. 堪培拉\n"
+ "E. 布里斯班\n";
System.out.println(question);
String answer = scanner.next().toUpperCase();
while (true) {
if (answer.equals("D")) {
System.out.println("正确");
break;
} else if (answer.equals("A") || answer.equals("B") || answer.equals("C") || answer.equals("E")) {
System.out.println("回答错误，请重试。");
} else {
System.out.println("输入错误");
}
answer = scanner.next().toUpperCase();
}
}
简化检查错误答案的部分，你可以使用：
String[] wrong = {"A", "B", "C", "E"};
...
Arrays.asList(wrong).contains(answer);
英文:
You can do it something like this:
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String question = "What is the capital of Australia? \n"
+ "A. Sydney\n"
+ "B. Melbourne\n"
+ "C. Perth\n"
+ "D. Canberra\n"
+ "E. Brisbane\n";
System.out.println(question);
String answer = scanner.next().toUpperCase();
while (true) {
if (answer.equals("D")) {
System.out.println("Correct");
break;
} else if (answer.equals("A") || answer.equals("B") || answer.equals("C") || answer.equals("E")) {
System.out.println("Wrong answer, try again.");
} else {
System.out.println("Incorrect input");
}
answer = scanner.next().toUpperCase();
}
}
I am using only console, without JPannels, but You can get the logic
Result console:
What is the capital of Australia?
A. Sydney
B. Melburne
C. Perth
D. Cannberra
E. Brisbane
a
Wrong answer, try again.
b
Wrong answer, try again.
p
Incorrect input
d
Correct
<hr>
To make checking worng values shorter You can use:
String[] wrong = {"A", "B", "C", "E"};
...
Arrays.asList(wrong).contains(answer)
答案2
得分: 0
如果你在while循环开始时就要求答案，你只需要写一次：
String answer = null;
while (true) {
answer = scanner.next().toUpperCase();
if (answer.equals("D")) {
System.out.println("正确");
break;
} else if (answer.equals("A") || answer.equals("B") || answer.equals("C") || answer.equals("E")) {
System.out.println("回答错误，请重试。");
} else {
System.out.println("输入有误");
}
}
这也解决了你的错误 
英文:
If you ask for the answer at the beginning of the while you only have to write it once:
String answer =null;
while (true) {
answer = scanner.next().toUpperCase();
if (answer.equals("D")) {
System.out.println("Correct");
break;
} else if (answer.equals("A") || answer.equals("B") || answer.equals("C") || answer.equals("E")) {
System.out.println("Wrong answer, try again.");
} else {
System.out.println("Incorrect input");
}
}
And it also solves your bug
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