雖然循環在Java

Question

我想寫一個程序，當用戶輸入「y」或「是」它會循環。

System.out.println("Tuition Wasted Based on Studnet Absences and its effacton GPA"); 

System.out.println("Enter the number of students to consider: "); 

students = keyboard.nextInt(); 

while (choice == y) 
{ 

if (students >= 1 && students <= 5) 

{ 
for(int i = 0; i < students; i++) 
{ 
    System.out.print("\nEnter the student ID for student: "); 
    studentID = keyboard.nextDouble(); 

    System.out.println("Do you want to run the program again?"); 

    choice = keyboard.nextInt(); 
} 

請幫我每次在Y型或yes我不斷收到錯誤

Answer 1

有很多錯誤的時間在這裏...

1. 什麼的Y？您已經編寫了代碼，好像有一個變量 y。根據choice的類型，while (choice == y)行中的y需要使用單引號或雙引號。

2. 什麼是choice第一次通過while循環？它在哪裏宣佈？它的類型是什麼？

3. 什麼是nextInt()的退貨類型？提示：int :-)這會影響你是否用單引號或雙引號包裝y。看着成char與字符串在Java中，以及它們是如何比較？

Answer 2

在使用while循環，你應該首先聲明在聲明它的初始值。

實施例：

String choice ="y"

//and so on...

while (choice.equals("y")) {

//your stuffs here

}

PS

"y"是什麼數據類型？我假設你宣佈它爲Integer cus你使用了一個"=="簽署你不能使用"double-equals"登錄String。您應該將其更改爲String，並改爲使用".equals"。

儘量考慮使用do-while循環

例：

//your declarations..and so on

String choice;

System.out.println("Tuition Wasted Based on Studnet Absences and its effacton GPA");

System.out.println("Enter the number of students to consider: ");

students = keyboard.nextInt();

do {

​​

{ for(int i = 0; i < students; i++) {

System.out.print("\nEnter the student ID for student: "); 
studentID = keyboard.nextDouble();` 

System.out.println("Do you want to run the program again?");` 

choice = keyboard.next(); 

}while (choice.equals("y") || choice.equals("yes"));