Open file in editor java

Text Editor in Java with Source Code

Today, I am going to make a Text Editor program using our Java. Yeah, Like notepad. I want to add some basic functionalities like Opening a file, Saving a file and option to change the font size. It will only take less than 100 lines of code to do this (Excluding User Interface).

I started with the toolbar javax.swing.JToolBar and added 4 buttons. Button with simple label logo and text for open,save and font size changing. The display area is simply a JTextArea with monotype font.

Opening a Text File

It is pretty straightforward to use JFileChooser to select a file. When I started thinking about opening a file, I wanted a File Chooser that filter and display only text files.Thanks to FileNameExtensionFilter from javax.swing.filechooser.FileNameExtensionFilter. I am able to display only text files on the JFileChooser using the code

FileNameExtensionFilter filter = new FileNameExtensionFilter("TEXT FILES", "txt", "text"); fileOpener.setFileFilter(filter); 

When the user selects a file and click open, The Scanner from java.util.Scanner is used to read the file.

Scanner scn = new Scanner(file); String buffer = ""; while (scn.hasNext()) < buffer += scn.nextLine() + "\n"; >display.setText(buffer); 

The “file” is nothing but the file taken from the JFileChooser and the while loop will continue until the end of file. “display” is the name of JTextArea, our display.

Saving a Text File

A global file variable called “currentEditingFile” is maintained to know whether we are working on a new, unsaved data or on an opened file. If “currentEditingFile” is null we have a new uncreated file. So the saving method will look to “currentEditingFile” and if it is null a JFileChooser will be opened to select the location for the new file. After selecting the directory, file name is taken from JOptionPane input dialog.

Changing Font Size

A global variable with default font size as 14 is maintained and increased or decreased depending upon the button pressed.

display.setFont(new java.awt.Font("Monospaced", 0, ++fontSize)); //Increase font size display.setFont(new java.awt.Font("Monospaced", 0, --fontSize)); //Decrease font size 

Extra Works

It is not acceptable to exit the program without any notice when the user clicks on the Close button. In order to add a save confirmation, i made an override on the Window Closing operating and added a confirmation message. It is done from the constructor itself

this.addWindowListener(new WindowAdapter() < @Override public void windowClosing(WindowEvent e) < super.windowClosing(e); //To change body of generated methods, choose Tools | Templates. int ans = JOptionPane.showConfirmDialog(rootPane, "Save Changes ?", "Confirm", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE); if (ans == JOptionPane.YES_OPTION) < //Write Changes saveChanges(); >> >); 

So that’s it. Download the program / source code from below buttons. If this was helpful please like me on facebook and keep visiting for more cool programs and sources.

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How to open user system preferred editor for given file in Java?

If you need to open a file in a user’s preferred system editor in Java, there are several methods that you can use to achieve this. The preferred system editor can be different for each operating system, and as a result, you may need to take into consideration the operating system that your Java application is running on. In this article, we will look at several methods to open a file in the user’s preferred system editor.

Method 1: Using the Runtime class

To open the user system preferred editor for a given file in Java using the Runtime class, you can follow these steps:

1. Create a File object with the path to the file you want to open.
2. Get the absolute path of the file using the getAbsolutePath() method of the File class.
3. Create a Runtime object using the getRuntime() method.
4. Use the exec() method of the Runtime class to execute the command to open the file with the system preferred editor. Pass the command as a string to the exec() method.
5. Use the waitFor() method of the Process class to wait for the editor to close before continuing with the program.

Here is an example code snippet that demonstrates how to open a file using the user system preferred editor:

import java.io.File; import java.io.IOException; public class OpenFileWithEditor  public static void main(String[] args) throws IOException, InterruptedException  // Create a File object with the path to the file you want to open File file = new File("path/to/your/file.txt"); // Get the absolute path of the file String filePath = file.getAbsolutePath(); // Create a Runtime object Runtime runtime = Runtime.getRuntime(); // Use the exec() method to execute the command to open the file with the system preferred editor Process process = runtime.exec("cmd /c start " + filePath); // Use the waitFor() method to wait for the editor to close process.waitFor(); > >

In this example, the cmd /c start command is used to open the file with the system preferred editor. The waitFor() method is used to wait for the editor to close before continuing with the program.

Method 2: Using the Desktop class

To open a user system preferred editor for a given file in Java using the Desktop class, follow these steps:

1. Create a File object representing the file you want to open.
2. Create an instance of the Desktop class.
3. Call the edit() method of the Desktop instance, passing in the File object as a parameter.

import java.awt.Desktop; import java.io.File; import java.io.IOException; public class OpenEditorUsingDesktop  public static void main(String[] args)  File file = new File("path/to/your/file.txt"); // check if Desktop is supported if (!Desktop.isDesktopSupported())  System.out.println("Desktop is not supported"); return; > Desktop desktop = Desktop.getDesktop(); // check if the file exists if (!file.exists())  System.out.println("File does not exist"); return; > // open the file with the default editor try  desktop.edit(file); > catch (IOException e)  e.printStackTrace(); > > >

This code first checks if the Desktop class is supported by the current platform. If it is, it then creates an instance of the class and checks if the file exists. Finally, it calls the edit() method of the Desktop instance, passing in the File object as a parameter to open the file with the system’s default editor.

Note that the edit() method may not work on all platforms or may not have a default editor set up for certain file types. In such cases, an IOException will be thrown.

Method 3: Using an external library such as Apache Commons Exec

Here is an example code to open a file in the user’s preferred editor using Apache Commons Exec library:

import java.io.File; import java.io.IOException; import org.apache.commons.exec.CommandLine; import org.apache.commons.exec.DefaultExecutor; import org.apache.commons.exec.ExecuteException; public class OpenFileInEditor  public static void main(String[] args) throws ExecuteException, IOException  // Specify the file path to open in the editor String filePath = "/path/to/file.txt"; // Create a File object for the file path File file = new File(filePath); // Get the command line to open the file in the user's preferred editor CommandLine commandLine = CommandLine.parse("open " + file.getAbsolutePath()); // Create a DefaultExecutor instance DefaultExecutor executor = new DefaultExecutor(); // Execute the command line executor.execute(commandLine); System.out.println("File opened in editor."); > >

1. Import the necessary classes from the Apache Commons Exec library.
2. Create a class named OpenFileInEditor .
3. In the main method, specify the file path of the file to open in the editor.
4. Create a File object for the file path.
5. Create a CommandLine object with the command to open the file in the user’s preferred editor. In this example, the open command is used for macOS. For other operating systems, the command may be different.
6. Create a DefaultExecutor instance.
7. Execute the command line using the execute method of the DefaultExecutor instance.
8. Print a message to the console indicating that the file has been opened in the editor.

Note: This example code is for macOS. For other operating systems, the command to open a file in the user’s preferred editor may be different.

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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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