Open file window in java

Open file window in java

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How to open a File in Java

While we believe that this content benefits our community, we have not yet thoroughly reviewed it. If you have any suggestions for improvements, please let us know by clicking the “report an issue“ button at the bottom of the tutorial.

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.

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How to open file explorer in java

Sometimes, we come across requirements where we need to open a particular folder or directory in the native file explorer. In this tutorial, we will see how to do that, easy and effective.

Opening file explorer with java in any platform – Windows, Linux and Mac

The easiest way to do this is by using Java Desktop. The class provides an open() function Desktop#open(File) to open explorer when the given file is a directory.

private static void openDirectory() throws IOException < File directory = new File("C://Program Files//"); Desktop.getDesktop().open(directory); >

From Java 9 onwards, Desktop is available on the java.desktop module. So, make sure to add “requires java.desktop;” to your module-info.java file.

Open file explorer and select/highlight a file

Now, if you want to open the file explorer and have a file preselected, then there is a way for that as well! You can make use of Desktop.fileBrowseDirectory(File) to launch the file explorer and have a file highlighted. Let’s see a code example for the same.

However, before using this function, you have to keep the following things in mind.

• The code will not work on ALL platforms.
• You need to check whether the feature is supported via Desktop.getDesktop().isSupported(Action.BROWSE_FILE_DIR) function.
• Minimum Java 9 is required

import java.awt.Desktop; import java.awt.Desktop.Action; import java.io.File; public class JavaFileExplorer < public static void main(String[] args) < openDirectory(); >private static void openDirectory() < //Check if the feature supported on your platform if (Desktop.getDesktop().isSupported(Action.BROWSE_FILE_DIR)) < File directory = new File("/home/afsal/Downloads/jdk-8u212-linux-x64.tar.gz"); //Open directory with browse_file_dir option Desktop.getDesktop().browseFileDirectory(directory); >> >

Open file explorer in Linux

Now, if you would like to add specific code for Linux/Ubuntu to open the file explorer, have a look into the following code snippet. We can make use of the xdg-open command to open any directory. The good thing about using this method is that, it works across multiple Linux distributions. They just have to have the xdg-open support.

private static void openDirectoryInLinux() throws Exception < Runtime.getRuntime().exec( new String[]); >

Open file explorer in Windows

Now, if you would like to add specific code for Windows OS to open the file explorer, have a look into the following code snippet. We will execute a cmd command to open Windows explorer.exe.

private static void openDirectoryInWindows() throws Exception

Open file explorer in MacOS

If you are looking for specific code for macOS, you can make use of the /usr/bin/open function to open the directory on macOS.

private static void openDirectoryInMac() throws Exception < Runtime.getRuntime().exec(new String[]); >

Conclusion

In this tutorial, we have learned how to open a directory from a java program. We have numerous methods to achieve the same goal here. We can use java.awt.Desktop for platform independent support and if platform-specific implementation is required, that is also available. You might also be interested in the following topics.

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How to Open a File in Java

Java is an object-oriented language that offers various predefined packages, classes, and methods for performing different tasks. While writing a Java program, you may need to open a file and perform some related operations. Don’t know how to do that? Using the built-in Java classes, you can open files without any hassle.

This guide will teach the method of opening a file in Java. So, let’s start!

Java Classes Used for Opening a File

In Java, you can utilize any of the given classes in your program for opening a file:

• Java Scanner class
• Java Desktop class
• Java BufferedReader class
• Java FileReader class
• Java FileInputStream class
• Java nio Package

Here, we will discuss the top three most utilized Java classes for opening a file.

Method 1: Opening a File Using the Java Scanner Class

The java.util package contains the Scanner class. The constructor of the Java Scanner class enables you to open and read the file’s content by taking a file as an argument. The Scanner class also provides various methods for reading data from a file, such as the nextLine() method.

Example
In this example, we will use the Java Scanner class to open and read the content of the java11.txt file. To do so, import the java.util.Scanner class and follow the given instructions:

• Firstly, in the try block, we will create a variable named myfile that will be used to refer to the required file using the given path.
• Then, we will create a Scanner class object named openfile and pass myfile to it as an argument.
• Within the while loop, the object openfile will call the method hasNextLine() to read the file by using the nextLine()
• Close the scanner object openfile by using the close()

try {
File myfile = new File ( «E: \\ Java \\ java11.txt» ) ;
Scanner openfile = new Scanner ( myfile ) ;
while ( openfile. hasNextLine ( ) ) {
String filedata = openfile. nextLine ( ) ;
System . out . println ( filedata ) ;
}
openfile. close ( ) ;
}

If the particular file does not exist, catch block will throw FileNotFoundException:

catch ( FileNotFoundException e ) {
System . out . println ( «Error.» ) ;
e. printStackTrace ( ) ;
}

The given output indicates that we have successfully read the content of our java11.txt file:

Now, let’s head toward the other method for opening a file in a Java program.

Method 2: Opening a File Using FileInputStream Class

FileInputStream is another Java class that can be utilized for opening and reading a file in Java. Similar to the Scanner class constructor, the constructor of the FileInputStream class also accepts the file as an argument. However, it reads the file in the form of bytes.

Example
The below example will show the method to open a file using FileInputStream class. Here is the list of steps that we have followed:

• Firstly, import the io.FileInputStream package into your project.
• In the try block, we will create a variable named myfile that accepts the file’s location as an argument.
• Then, create an object of the FileInputStream class named openfile and pass the created file variable to it.
• In the added while loop, the object openfile will read the required file in byte form.

try {
File myfile = new File ( «E: \\ Java \\ java11.txt» ) ;
FileInputStream openfile = new FileInputStream ( myfile ) ;
System . out . println ( «File content: » ) ;
int i = 0 ;
while ( ( i = openfile. read ( ) ) !=- 1 )
{
System . out . print ( ( char ) i ) ;
}
}

The catch block will throw an Exception if the file does not exist:

Method 3: Opening a File Using the Java BufferedReader Class

The BufferedReader class belongs to the java.io package. Its constructor can be utilized for opening and reading the text with the help of a character input stream.

Example
Have a look at the below-given example to open a file in a Java program with the help of Buffered Reader class:

• Firstly, import theio package for the BufferedReader class in your project.
• Add a try block and create a variable named myfile that accepts the file path as an argument.
• Then, create an object of the BufferedReader class named openfile and pass a file to it.
• The openfile object will read the file by using buffering-character input stream.

try {
File myfile = new File ( «E: \\ Java \\ java11.txt» ) ;
BufferedReader openfile = new BufferedReader ( new FileReader ( myfile ) ) ;
System . out . println ( «The content of file: » ) ;
int i = 0 ;
while ( ( i = openfile. read ( ) ) != — 1 ) {
System . out . print ( ( char ) i ) ;
}
}

Lastly, add a catch block that throws an Exception if the file does not exist:

We have given all the important information related to opening a file in Java.

Conclusion

To open and read a file in Java, we have predefined packages, methods, and classes, including the Scanner class, FileInputStream Class, and BufferedReader class. The Scanner class offers different methods to read data while the FileInputStream Class reads data in the form of bytes and the BufferedReader Class reads in the form of buffering-character input streams. This guide discussed the procedure related to opening a file in Java.

About the author

Farah Batool

I completed my master’s degree in computer science. I am an academic researcher and love to learn and write about new technologies. I am passionate about writing and sharing my experience with the world.

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