[英]Always receiving FileNotFoundException, even with file in SRC folder
[英]receiving FileNotFoundException even though throws statement is present
我编写了以下代码,该代码将随机生成的字符列表打印到文件中,然后从文件中读取它们,然后使用异或将其加密,然后再次打印。 问题是,即使我将它放在throws语句中,我仍然收到FileNotFoundException。
/**
* @param args the command line arguments
*/
public static void main(String[] args) throws FileNotFoundException {
//get integer mask from user input
int mask = getMask();
System.out.println("TEMP mask Value is: " + mask);
//create 50 character random String and save to file
String randomString = getRandomString(50);
System.out.println("Original Random Character String: " + '\n' + randomString);
//save 50 Char String from file
Scanner keyboard = new Scanner(System.in);
System.out.println("Saving encrypted string...");
System.out.print("Enter a file name: ");
String fileName = keyboard.next();
File outputFile = new File(fileName);
saveFile(fileName, randomString);
/*System.out.println("Saving Original Random Character string...");
Scanner keyboard = new Scanner(System.in);
System.out.print("Enter a file name: ");
String fileName = keyboard.next();
File outputFile = new File(fileName);
PrintWriter fileWriter = new PrintWriter(outputFile);
fileWriter.println(randomString);
fileWriter.close();//CLOSE OF FILEWRITER
*/
//scan in from file
Scanner file = new Scanner(outputFile);
String inputString = file.nextLine();
//print what was just scanned in from file
System.out.print("Original random character string from the file" +
'\n' + inputString + '\n');
//apply mask by convertig String to char using loop
String maskedString = maskString(inputString, mask);
System.out.print("Encrypted character string: " + '\n' + maskedString + '\n');
/*String maskedString = "";
for(int i = 0; i < inputString.length(); i++){
char charMasked = (char)(((int) inputString.charAt(i))^mask);
maskedString += charMasked;
}//end of for loop
System.out.print("Encrypted character string: " + '\n' + maskedString + '\n');
*/
//save encrypted string
System.out.println("Saving encrypted string...");
System.out.print("Enter a file name: ");
String encryptedFileName = keyboard.nextLine();
saveFile(encryptedFileName, maskedString);
}//end of main method
/**
* Preconditions: must call randomString method to get random
* characters
* Postconditions: user will have a string of random characters of desired
* length
* @param count allows user to choose how many random characters to return
*/
public static String getRandomString(int count)throws FileNotFoundException{
String listChars = "";
for (int i = 0; i < count; i++) {
char randomChar = (char) ((Math.random() * 255) + 32);/////////////////////getting less than 50 characters sometimes, possible control characters?
listChars += randomChar;
}//end of for loop
return listChars;
}//end of randomString method
/**
* Precondition: must call getMask method to get prompt user to enter the
* encryption mask that will be used to encrypt the file input
* Postcondition: user has entered an integer string that will be used to
* encrypt the 50 char random String we will read from a file
* @return output, which is the user entered integer value
*/
public static int getMask(){
//Prompt user to enter integer mask
System.out.print("Enter the encryption mask: ");
Scanner keyboard = new Scanner(System.in);
int output = keyboard.nextInt();
return output;
}//end of getMask method
public static void saveFile(String fileName, String toBePrinted)throws FileNotFoundException{
File outputFile = new File(fileName);
PrintWriter fileWriter = new PrintWriter(outputFile);
fileWriter.println(toBePrinted);
fileWriter.close();//CLOSE OF FILEWRITER
}//end of saveFile method
public static String maskString(String inputString, int mask){
String maskedString = "";
for(int i = 0; i < inputString.length(); i++){
char charMasked = (char)(((int) inputString.charAt(i))^mask);
maskedString += charMasked;
}//end of for loop
return maskedString;
}//end of maskString method
在执行我的代码后,我Exception in thread "main" java.io.FileNotFoundException: (No such file or directory)
收到了类似Exception in thread "main" java.io.FileNotFoundException: (No such file or directory)
。 我认为可以通过使用throws FileNotFoundException
语句来防止此错误。
我已经在这里查看了Oracle Java教程
我正在诚实地尝试,但只是没有点击我。 我只用过try-catch语句来捕获这样的异常。 这是我每次尝试保存以前未创建的文件时需要在这里执行的吗?
方法签名中的throws
子句仅表示“我知道此方法会引发此异常,并且在此处未捕获此异常,因此调用方应捕获该异常。”
在您的示例中,您只是在欺骗编译器,以便它不会抱怨未捕获的异常。
通过添加FileNotFoundException,您正在声明该函数可能会引发此异常,但是您并未添加任何将捕获并抑制该异常的内容。
我会将您的代码包装到一个函数/类中,然后在您的主代码块中添加一个try块来调用您的函数/类,并为FileNotFoundException添加catch块。
throws
子句不能避免引发异常。 实际上,它只是将方法声明为抛出此类异常,以便其他调用它的方法可以相应地对其进行处理。
如果要抑制异常,则必须在语句周围加上try-catch
语句。 但是,禁止例外不是一个好习惯。 您应该正确对待它们,并向您的用户显示兼容消息。
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