Why can't I find my File?

问题:

I'm trying to open a CSV file name "logger.csv" which I have saved in the source folder itself.

public static void main(String[] args) {
    String filename = "logger.csv";
    File motor_readings = new File(filename);
    try {
        Scanner inputStream = new Scanner(motor_readings);
        while (inputStream.hasNext()){
            System.out.println(inputStream.next());
        }
        inputStream.close();
    } catch (FileNotFoundException e) {
        System.out.println("Error: File not found!");
    }
}

However, this keeps on giving me a "File not found" error.

回答1:

If you use relative pathing as you are right now - the file needs to exist in the project root, not in the directory of the java file.

Consider this hierarchy:

project/
  src/main/java
    file.java
    logger.csv

new File("logger.csv") will not work.

project/
  logger.csv
  src/main/java
    file.java

new File("logger.csv") will now work. (notice, the file is adjacent to the src directory.)

回答2:

Put the file on level up. In the main folder of the project.

回答3:

To see where the file is expected update the code in your catch clause to:

        System.out.println("Error: File not found: " + motor_readings.getAbsolutePath());

Put it there and be sure to refresh your workspace in Eclipse so that the file can be seen.