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Check if a File Exists in Java

beginner· File Handling · File I/O

Problem

Before reading, writing or deleting, programs often need to know whether a path exists and whether it's a regular file or a directory.

Check for a settings file before and after creating it, print its details, then delete it and check again.

Input

settings.cfg

Output

false → true → deleted

Java Program

Java

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class CheckFileExists {
    public static void main(String[] args) throws IOException {
        Path file = Paths.get("settings.cfg");

        System.out.println("Exists before creating: " + Files.exists(file));

        Files.writeString(file, "theme=dark");
        System.out.println("Exists after creating:  " + Files.exists(file));
        System.out.println("Is a regular file: " + Files.isRegularFile(file));
        System.out.println("Is a directory:    " + Files.isDirectory(file));
        System.out.println("Size in bytes:     " + Files.size(file));

        boolean removed = Files.deleteIfExists(file); // no exception if it's already gone
        System.out.println("Deleted: " + removed + ", exists now: " + Files.exists(file));
    }
}

▶ Run Code

Output

Exists before creating: false
Exists after creating:  true
Is a regular file: true
Is a directory:    false
Size in bytes:     10
Deleted: true, exists now: false

Core Logic

The Files class answers each question about a path with a single static method.

How It Works

1Files.exists(file) is false before the file is created.
2Files.writeString creates it, after which exists is true.
3isRegularFile, isDirectory and size describe the path.
4deleteIfExists removes it and returns whether anything was deleted.

theme=dark is 10 characters, so the file is 10 bytes.

💡

Key Point: Checking exists() and then acting is a race in multi-user systems — the file can vanish in between; methods like deleteIfExists do the check and the action together.

Key Concepts

Files.exists()Files.isRegularFile()Files.size()Files.deleteIfExists()

Approach 2: Using java.io.File

Java

import java.io.File;
import java.io.IOException;

public class CheckFileExistsIo {
    public static void main(String[] args) throws IOException {
        File file = new File("settings.cfg");

        System.out.println("exists(): " + file.exists());
        System.out.println("createNewFile(): " + file.createNewFile()); // true only if it was actually created
        System.out.println("exists(): " + file.exists() + ", isFile(): " + file.isFile());
        System.out.println("delete(): " + file.delete());
        System.out.println("exists(): " + file.exists());
    }
}

▶ Run Code

Output

exists(): false
createNewFile(): true
exists(): true, isFile(): true
delete(): true
exists(): false

Core Logic

The older java.io.File API offers the same checks as instance methods that return booleans.

How It Works

1file.exists() and file.isFile() describe the path.
2createNewFile() returns true only if it actually created the file.
3delete() returns true on success.

The second exists() call returns true after createNewFile(), and the last one returns false after delete().

💡

Key Point: File.delete() just returns false on failure with no reason given; Files.delete throws an exception that explains what went wrong.