How to open a File in Java

Sometimes we have to open a file in java program. java.awt.Desktop can be used to open a file in java. Desktop implementation is platform dependent, so first, we should check if the operating system supports Desktop or not. This class looks for the associated application registered to the current platform to open a file.

Java Open File

Let’s have a look at the simple java open file program. If we try to open a file that doesn’t exist, it will throw java.lang.IllegalArgumentException. Let’s see Desktop class example for java open file. JavaOpenFile.java

package com.journaldev.files;

import java.awt.Desktop;
import java.io.File;
import java.io.IOException;

public class JavaOpenFile {

    public static void main(String[] args) throws IOException {
        //text file, should be opening in default text editor
        File file = new File("/Users/pankaj/source.txt");
        
        //first check if Desktop is supported by Platform or not
        if(!Desktop.isDesktopSupported()){
            System.out.println("Desktop is not supported");
            return;
        }
        
        Desktop desktop = Desktop.getDesktop();
        if(file.exists()) desktop.open(file);
        
        //let's try to open PDF file
        file = new File("/Users/pankaj/java.pdf");
        if(file.exists()) desktop.open(file);
    }

}

When you run the above program, the text file will be opened in the default text editor. Similarly, a PDF file will be opened in adobe acrobat reader. If there are no application associated with given file type or the application is failed to launch, open method throws java.io.IOException. That’s all for a simple program to open a file in java.