我正在运行我的程序，并尝试从该程序运行的程序启动“帮助”菜单（如果这有意义！）。但是我得到了一个“NoSuchElement”异常，在我的try {} catch()中甚至都没有在这两个程序中调用！
我正在做的是;
运行程序。键入“create”以启动commandCreate类。然后我输入“帮助”以启动帮助菜单。但我得到了NoSuchElement异常。如果有人能够帮助我，我的两个程序在下面。谢谢。
// main.java
import java.io.*;
public class Main extends API {
boolean _active = true;
String _username = System.getProperty("user.name").toLowerCase();
String _os = System.getProperty("os.name").trim().toLowerCase();
public Main() {
try {
while(_active) {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
print(_username + "@" + _os + ":~$ ");
String command = br.readLine();
if(command.equalsIgnoreCase("create")) {
new commandCreate();
/*} else if(command.equals("compile")) {
new commandCompile();*/
} else if(command.equalsIgnoreCase("help")) {
println("Commands");
println(" create - Creates .java files, does not compile.");
//println(" compile - Creates .java files, compiles on creation.");
println(" exit - Exits program");
println(" help - Shows help documentation.");
} else if(command.equalsIgnoreCase("exit")) {
print("Are you sure you want to exit? (Y/N) ");
String exit = br.readLine();
if(exit.equalsIgnoreCase("y")) {
exit();
} else {
println("Cancelled!");
}
} else if(command.isEmpty()) {
} else {
println("\"" + command + "\" does not exist. Please review the \"help\" menu");
}
}
} catch(Exception ex) {
println("There was a problem: " + ex);
}
}
public static void main(String[] args) {
new Main();
}
}
// commandCreate.java
import java.util.*;
import java.io.*;
public class commandCreate {
boolean _active = true;
String _username = System.getProperty("user.name").toLowerCase();
String _os = System.getProperty("os.name").trim().toLowerCase();
String fileName, create, option;
public commandCreate() {
try {
System.out.print(_username + "@" + _os + ":~/create$ ");
Scanner kbd = new Scanner(System.in);
String userLine = kbd.nextLine();
Scanner read = new Scanner(userLine);
option = read.next();
fileName = read.next();
FileWriter create = new FileWriter(new File("Created Files/" + fileName + ".java"));
if(userLine.equals(option + " " + fileName)) {
if(option.equals("-a")) {
// Option = -a, creates standard file with main class.
create.write("public class " + fileName + " {\n");
create.write(" public static void main(String[] args) {\n");
create.write(" System.out.println(\"Welcome to your new program!\");\n");
create.write(" }\n");
create.write("}");
} else if(option.equals("-c")) {
// Option = -c , creates standard file with overloaded constructor & main class.
create.write("public class " + fileName + " {\n");
create.write(" public " + fileName + "() {\n");
create.write(" System.out.println(\"Welcome to your new program!\");\n");
create.write(" }\n");
create.write("\n");
create.write(" public static void main(String[] args) {\n");
create.write(" new " + fileName + "();\n");
create.write(" }\n");
create.write("}");
} else if(option.equals("-j")) {
// Option = -j, creates GUI within constructor w/ single JLabel.
create.write("import javax.swing.*;\n");
create.write("import java.awt.*;\n");
create.write("import java.awt.event.*;\n");
create.write("\n");
create.write("public class " + fileName + " extends JFrame {\n");
create.write(" private static final int HEIGHT = 50;\n");
create.write(" private static final int WIDTH = 400;\n");
create.write("\n");
create.write(" private JLabel welcomeJ;\n");
create.write("\n");
create.write(" public " + fileName + "() {\n");
create.write(" super(\"Welcome to your program - " + fileName + "\");\n");
create.write(" Container pane = getContentPane();\n");
create.write(" setLayout(new FlowLayout());\n");
create.write("\n");
create.write(" welcomeJ = new JLabel(\"Welcome To Your Program!\", SwingConstants.CENTER);\n");
create.write("\n");
create.write(" pane.add(welcomeJ);\n");
create.write("\n");
create.write(" setSize(WIDTH, HEIGHT);\n");
create.write(" setVisible(true);\n");
create.write(" setResizable(false);\n");
create.write(" setDefaultCloseOperation(EXIT_ON_CLOSE);\n");
create.write(" }\n");
create.write("\n");
create.write(" public static void main(String[] args) {\n");
create.write(" new " + fileName + "();\n");
create.write(" }\n");
create.write("}");
}
} else if(userLine.equalsIgnoreCase("help")) {
System.out.println("Commands");
System.out.println(" Syntax: [-option] [filename]");
System.out.println(" -a [filename] [Program: main class]");
System.out.println(" -c [filename] [Program: overloaded constructor, main class]");
System.out.println(" -j [filename] [Program: GUI: overloaded constructor, main class]");
} else {
System.out.println("Error in syntax. Please review the \"help\" menu");
}
create.close();
} catch(IOException e) {
System.out.println("There was an error: " + e);
} catch(InputMismatchException ex) {
System.out.println("There was an error: " + ex);
}
}
public static void main(String[] args) {
new commandCreate();
}
}
答案 0 :(得分：2)
根据您的堆栈跟踪，问题在于：
Scanner kbd = new Scanner(System.in);
String userLine = kbd.nextLine();
Scanner read = new Scanner(userLine);
option = read.next();
fileName = read.next(); // <--- exception here
这段代码的作用是：
userLine。userLine读取两个以空格分隔的标记，并将其保存为option和filename。所以问题是来自标准输入的行实际上没有两个以空格分隔的标记。它需要看起来像-j file.txt，但可能只是看起来像-j，或者像file.txt。
答案 1 :(得分：1)
您可能在名为API的超类中遇到问题。看那里。