我有一个菜单，所以用户可以从中选择，但是当我输入我选择的号码时，我看不到结果，而是再次显示菜单！谁能告诉我问题在哪里？提前谢谢
import javax.swing.JOptionPane;
public class StudentsMarkComputerProject
{
public static void main(String args[])
{
JOptionPane.showMessageDialog(null, "Welcome");
JOptionPane.showMessageDialog(null, "Students mark Input Project");
JOptionPane.showMessageDialog(null, "In this program the user is going to enter the students name, class and marks.Then the program is going to output several information about each student.");
JOptionPane.showMessageDialog(null, "Class Information must be entered as the name of the class, the subject and the number of students");
String nameofclass = JOptionPane.showInputDialog("Enter the name of the class");
String nameofsubject = JOptionPane.showInputDialog("Enter the subject");
int numberofstudents =Integer.parseInt(JOptionPane.showInputDialog("Enter the number of students"));
JOptionPane.showMessageDialog(null,"Class Students Information");
JOptionPane.showMessageDialog(null,"You must enter the name, surname and " + nameofsubject + " marks for each and every student in class "+ nameofclass);
StLuciaClassrooms theclass =new StLuciaClassrooms(nameofclass, numberofstudents);
theclass.enterInformation(numberofstudents);
int option = 0;
do
{
String ques = "<html><body><b>-----------------Menu Options--------------</b><br/>"
+ "Here you need to enter a number between 1 and 6 according your choice.<br/>"
+ "----------------------------------------------------------------------------<br/>"
+ "1.Search for a particular student.<br/>"
+ "2.Show students names, marks and grades.<br/>"
+ "3.Display passes.<br/>"
+ "4.Display failures.<br/>"
+ "5.Show statistics.<br/>"
+ "6.Exit.<br/>"
+ "Enter you choice<br/></body></html>";
int opt = Integer.parseInt(JOptionPane.showInputDialog(ques));
System.out.println(opt);
switch (option)
{
case 1:
String name = JOptionPane.showInputDialog("Enter the name of the student you want to search for");
String surname = JOptionPane.showInputDialog("Enter the surname of the class");
theclass.searchStudents(numberofstudents,name,surname);
break;
case 2://show students names, marks and grades
theclass.showInformation(numberofstudents);
break;
case 3://display passes
theclass.displayPasses(numberofstudents);
break;
case 4://display failures
theclass.displayFailures(numberofstudents);
break;
case 5 :
theclass.showStatistics(numberofstudents);
break ;
case 6 ://exit
System.out.println("Thanks for using this program , Hope to see you again ! . Have a nice day ");
break;
default :
System.out.println("Error ! ");
}
}while(option !=6);
}
}
import javax.swing.JOptionPane;
class StLuciaClassrooms
{
String nameofclass;
StLuciaStudents[] students;//array declaration is done only with square brackets "[]"
public StLuciaClassrooms (String nameofclass, int numberofstudents)
{
this.nameofclass = nameofclass;
students = new StLuciaStudents[numberofstudents];
}
public void enterInformation (int numberofstudents)
{
System.out.println("*********************************Please enter the student's information**********************");
for (int i=0;i < numberofstudents; i++)
{
String names=JOptionPane.showInputDialog("Enter sudents names");
String surnames=JOptionPane.showInputDialog("Enter students surnames");
int marks= Integer.parseInt(JOptionPane.showInputDialog("Enter the students marks"));
StLuciaStudents kid = new StLuciaStudents(names, surnames, marks);
students[i]=kid;
}
}
private String generateGrade (int marks)
{
String grade = "a";
if (marks < 50)
{
grade = ("F");
}else if (marks < 65)
{
grade = ("D");
}else if (marks<75)
{
grade = ("C");
}else if (marks <85)
{
grade = ("B");
}else if (marks < 90)
{
grade = ("A");
}else if (marks >90&&marks<100)
{
grade = ("A+");
}else if (marks == 100)
{
grade = ("A++");
}else;
{
grade = "This is an invalid mark";
}
return grade ;
}
public void showInformation (int numberofstudents)
{
for (int i =0; i < numberofstudents ; i++)
{
System.out.println("Name : " + students[i].nameofstudents);
System.out.println("Surname:"+students[i].surnameofstudents);
System.out.println("Mark:"+ students[i].markofstudents);
System.out.println("Grade : " + generateGrade(students[i].markofstudents));
}
}
public void searchStudents (int numberofstudents, String nameofstudents, String surnameofstudents)
{
boolean flag = false;
for (int i=0; i<numberofstudents;i++)
{
if (students[i].nameofstudents.equalsIgnoreCase(nameofstudents) && students[i].surnameofstudents.equalsIgnoreCase(surnameofstudents))
{
flag = true ;
System.out.println(students[i].nameofstudents + students[i].surnameofstudents +" is found ! ");
}
}
}
public void displayFailures(int numberofstudents)
{
for (int i=0;i < numberofstudents;i++)
{
if (students[i].markofstudents < 50)
{
System.out.println(students[i].nameofstudents + students[i].surnameofstudents);
}
}
}
public void displayPasses(int numberofstudents)
{
for (int i=0;i < numberofstudents;i++)
{
if (students[i].markofstudents >=50)
{
System.out.println(students[i].nameofstudents + students[i].surnameofstudents);
}
}
}
public void showStatistics(int numberofstudents)
{
int total = 0;
int maxmark = students[0].markofstudents, first_stud=0;
int minmark = students[0].markofstudents, last_stud=0;
String maxname = " ",maxsurname = " ";
String minname = " ",minsurname = " ";
for (int i =1; i<numberofstudents; i++)
{
if (students[i].markofstudents > maxmark )//continue this as staistics are show in a particular case
{
maxmark = students[i].markofstudents;
maxname = students[i].nameofstudents;
maxsurname = students[i].surnameofstudents;
}
}
for (int i=1;i>numberofstudents;i++)
{
if (students[i].markofstudents < minmark)
{
minmark = students[0].markofstudents;
minname = students[i].nameofstudents;
minsurname=students[i].surnameofstudents;
}
}
double average = total/numberofstudents;
System.out.println("The maximum mark of" + maxname + maxsurname + " is " + maxmark);
System.out.println("The minimum mark of" + minname + minsurname + " is " + minmark);
System.out.println("The average is " + average);
}
}
答案 0 :(得分：1)
注意： int opt = Integer.parseInt(JOptionPane.showInputDialog(ques));
因此，您的选项存储在 opt 中。但你在switch case中使用选项。所以像这样改变
switch(opt){
}
可选
while(opt > 6);
所以你只有一次出现菜单并做你的行动。 如果只想出现一次，菜单会删除do while循环。