I want to find a value from an array

Question

Here's my java code:

import java.io.File;
import java.util.Arrays;



public class mainClass {

    public static void main(String... args) {
        File[] files = new File("%appdata%").listFiles();
        showFiles(files);
        System.out.println( Arrays.toString( files ) );
        if (Arrays.asList(files).contains(".minecraft")) {
            System.out.println("Success!");
        }
    }

    public static void showFiles(File[] files) {
    }

}

I want code above to check if .minecraft folder exists in %appdata%. I am total N00B to Java. I have worked with PHP, but doesn't seem to help me :) Please help, it annoys me.

-Simon

Start with [Basic I/O](http://docs.oracle.com/javase/tutorial/essential/io/) tutorial. — PM 77-1, Oct 30 '13 at 18:15
Please don't give negative votes to person who has shown what he did till now. — Jayesh, Oct 30 '13 at 18:19

score 2 · Accepted Answer · edited May 23 '17 at 12:28

2

If you are interested in finding only the ".minecraft" file it would be much easier to:

File appdata = new File("%appdata%");
File minecraft = new File(appdata, ".minecraft");
if (minecraft.exists()) {
    System.out.println("Success");
}

EDIT: Based on comment, (and I'm a linux guy mostly), you need to use the correct %APPDATA% location: How do I get the value of Windows' %APPDATA% location variable in Java?

edited May 23 '17 at 12:28

Community

1
1

answered Oct 30 '13 at 18:14

rolfl

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Here's my new code: `public class mainClass { File appdata = new File(System.getenv("APPDATA")); File minecraft = new File(appdata, ".minecraft"); if (minecraft.exists()) { System.out.println("Success"); } }` But it is giving my this error: **Error: Main method not found in class mainClass, please define the main method as: public static void main(String[] args) ** – AwesomeGuy Oct 31 '13 at 07:40

score 1 · Answer 2 · answered Oct 30 '13 at 18:15

The problem is that .minecraftis a hidden folder. You need to access the folder like this:

File directory = new File("%appdata%");    
File[] hiddenFiles = directory.listFiles((FileFilter) HiddenFileFilter.HIDDEN);
for (File hiddenFile: hiddenFiles) {
    System.out.println("hidden file: " + hiddenFile.getCanonicalPath());
}

score 0 · Answer 3 · answered Oct 30 '13 at 18:19

As rolfl mentioned, there is a better way to look for a single file.

That said, your code isn't performing a proper check. You are creating an array of File objects, converting the array to a List, and then checking the list for a String value. The String value will never match a File object.

If you want to find a single file, use rolfl's answer. If you want to fix your code specifically, here's something to get your started:

You need to iterate over the list of files. What do you gain by converting to a List?
You need to find a way to match a File's name with a String name. What method might you call on the File object to get its name?
You need to do a String comparison between the File's name and ".minecraft". What might that comparison look like?

Please note: reference L.Butz answer as well; I haven't accessed hidden files in Java, so it's possible there's an extra step you need to get access to them.

A4L · Answer 4 · 2013-10-30T18:52:45.533

%appdata%is an environment variable and as such it will not be automatically resolved by File. So you need to resolve it before listing it. This is done using System#getenv

@Test
public void dirExistsInAppData() {
    Assert.assertTrue(dirExistsInAppData(".minecraft"));
}

private boolean dirExistsInAppData(final String dirname) {
    File dir = new File(System.getenv("APPDATA"), dirname);
    return dir.exists() && dir.isDirectory();
}

I want to find a value from an array

4 Answers4