运行此代码时出现以下错误：
这是完整的Stackflow，任何输入都会受到赞赏;
Exception in thread "main" java.lang.NoClassDefFoundError: ExecuteQuiz
Caused by: java.lang.ClassNotFoundException: ExecuteQuiz
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
知道为什么吗？我有7个其他课程涉及该项目，但从未见过这个错误。
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
public class ExecuteQuiz {
static Scanner input = new Scanner(System.in);
public static void main(String[] args) throws IOException {
// ask the user for the filename
Scanner scan = new Scanner(System.in);
System.out.print("Which quiz are you taking? ");
String theFile = scan.nextLine(); // file may contain more than one word
File fileIn = new File(theFile);
// ask the user for another filename if the given file doesn't exist
// exists() method in File class - checks whether file
// exists and is readable
while (!fileIn.exists()) {
System.out.print("Invalid file name! Try again: ");
theFile = scan.nextLine();
fileIn = new File(theFile);
}
// have a valid file name, create a Scanner object
Scanner fileScan = new Scanner(fileIn);
// An arraylist of ALL problems.
ArrayList<Problem> problems = new ArrayList<Problem>();
// process the file
while (fileScan.hasNextLine()) {
String type = scan.nextLine(); // Get the line in a string
String question = scan.nextLine();
switch (type) {
case "W":
String WAnswer = scan.nextLine();
WProblem w = new WProblem(question, WAnswer);
problems.add(w);
break;
case "T":
String TString = scan.nextLine(); // Gets the string
boolean TAnswer = Boolean.parseBoolean(TString); // Converts to
// boolean
TProblem t = new TProblem(question, TAnswer); // Creates the
// object
problems.add(t);
break;
case "N":
String Nanswer = scan.nextLine();
NProblem n = new NProblem(question, Nanswer);
problems.add(n);
break;
case "S":
ArrayList<String> options = new ArrayList<String>();
// Get the answer and add it to the options
String SAnswer = input.nextLine();
options.add(SAnswer);
// add the rest of options
while (input.nextLine() != null) {
String option = input.nextLine();
options.add(option);
}
// Create new objects
SProblem s = new SProblem(question, SAnswer, options);
problems.add(s);
break;
case "M":
ArrayList<String> MAnswer = new ArrayList<String>();
ArrayList<String> MOptions = new ArrayList<String>();
// Find all the answers
while (input.nextLine() != null) {
String answer = input.nextLine();
MAnswer.add(answer);
MOptions.add(answer);
}
// get the rest of the options
while (input.nextLine() != null) {
MOptions.add(input.nextLine());
}
MProblem m = new MProblem(question, MAnswer, MOptions);
problems.add(m);
break;
case "O":
// Adding answers into an arraylist
ArrayList<String> OrderedAnswer = new ArrayList<String>();
// Add the answers in order
while (input.nextLine() != null) {
OrderedAnswer.add(input.nextLine());
}
OProblem o = new OProblem(question, OrderedAnswer);
problems.add(o);
break;
}
// Analyze the type of problem
}
}
}
答案 0 :(得分：1)
您的课程有重大的编译时间问题。你有没有编译代码并检查.. ??
开关案例在编译中给出错误：不兼容的类型
该类尚未编译，您正在尝试直接运行它。没有找到类定义错误。
尝试更改部分：
case "W":
到
case 1:
编译然后运行
我使用了以下代码：
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
public class ExecuteQuiz {
static Scanner input = new Scanner(System.in);
public static void main(String[] args) throws IOException {
// ask the user for the filename
Scanner scan = new Scanner(System.in);
System.out.print("Which quiz are you taking? ");
String theFile = scan.nextLine(); // file may contain more than one word
File fileIn = new File(theFile);
// ask the user for another filename if the given file doesn't exist
// exists() method in File class - checks whether file
// exists and is readable
while (!fileIn.exists()) {
System.out.print("Invalid file name! Try again: ");
theFile = scan.nextLine();
fileIn = new File(theFile);
}
// have a valid file name, create a Scanner object
Scanner fileScan = new Scanner(fileIn);
// An arraylist of ALL problems.
ArrayList<Problem> problems = new ArrayList<Problem>();
// process the file
while (fileScan.hasNextLine()) {
int type = Integer.parseInt(scan.nextLine()); // Get the line in a string
String question = scan.nextLine();
switch (type) {
case 1:
String WAnswer = scan.nextLine();
WProblem w = new WProblem(question, WAnswer);
problems.add(w);
break;
case 2:
String TString = scan.nextLine(); // Gets the string
boolean TAnswer = Boolean.parseBoolean(TString); // Converts to
// boolean
TProblem t = new TProblem(question, TAnswer); // Creates the
// object
problems.add(t);
break;
case 3:
String Nanswer = scan.nextLine();
NProblem n = new NProblem(question, Nanswer);
problems.add(n);
break;
case 4:
ArrayList<String> options = new ArrayList<String>();
// Get the answer and add it to the options
String SAnswer = input.nextLine();
options.add(SAnswer);
// add the rest of options
while (input.nextLine() != null) {
String option = input.nextLine();
options.add(option);
}
// Create new objects
SProblem s = new SProblem(question, SAnswer, options);
problems.add(s);
break;
case 5:
ArrayList<String> MAnswer = new ArrayList<String>();
ArrayList<String> MOptions = new ArrayList<String>();
// Find all the answers
while (input.nextLine() != null) {
String answer = input.nextLine();
MAnswer.add(answer);
MOptions.add(answer);
}
// get the rest of the options
while (input.nextLine() != null) {
MOptions.add(input.nextLine());
}
MProblem m = new MProblem(question, MAnswer, MOptions);
problems.add(m);
break;
case 6:
// Adding answers into an arraylist
ArrayList<String> OrderedAnswer = new ArrayList<String>();
// Add the answers in order
while (input.nextLine() != null) {
OrderedAnswer.add(input.nextLine());
}
OProblem o = new OProblem(question, OrderedAnswer);
problems.add(o);
break;
}
// Analyze the type of problem
}
}
}
答案 1 :(得分：0)
似乎ExecuteQuiz类不在classpath上。在类路径中设置它。
如果您在Windows上，可以将其设置如下
set CLASSPATH=%CLASSPATH%.;
答案 2 :(得分：0)
这不是编译器错误。
启动Java应用程序的典型方法是java -classpath <path> FullyQualifiedClassName
您的案例中的FullyQualifiedClassName是ExecuteQuiz
编译完成后，您的类将形成与类匹配的目录结构。提供该树的根作为类路径的一部分。您还应该添加任何其他依赖项，如jar。