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In this article, we will discuss Java Class File Editor, a tool created in Java to edit Java compiled classes. We can decompile Java classes after creating them and view them, but we need a tool like Java Class File Editor to modify them.

Features of Java Class File Editor

• Easy-to-use interface built with Java Swing
• Allows modification of various parts of class files, such as methods, strings, constants, etc.
• Consistency Check

Editing compiled Java classes using the Java class file editor

• Download the Java Class File Editor from https://sourceforge.net/projects/classeditor/files/
• Extract the compressed file and open the JAR file name ce.jaras shown below.

  
  If we are unable to open the file, we can open the command line/terminal and use the following command:

  java - jar c : ce.jar
  

• Once the editor is open, we use File > Openthe menu item to open a Java class file and select Explorer Class File.

• We will use the following code in our class file.

  public class ExampleClass1 {
    private static final String METHOD_NAME1 = "exampleMethod1";
    private static final String METHOD_NAME2 = "exampleMethod2";
  
    public static void main(String[] args) {
      int abc = 200;
      System.out.println(abc);
      exampleMethod2();
    }
  
    static void exampleMethod2() {
      System.out.println("This is just a method");
    }
  }
  

• After the editor opens the file, we turn on the modification mode in the upper right corner; this mode is off by default, as shown in the figure below. If it is on, the button will turn blue, and if it is off, it will turn green.

  

• Once editing is turned on, we can modify certain aspects of the class by entering different editor sections.

  The General section of the editor shows the class name and its parent classes. If there are interfaces in the class, we can view and edit the interfaces. The class access modifiers are also there and we can change them as needed.
  
  The next section is the Constant Pool section, which shows all the editor's constants in the class. Here we can change the type of the constants and their values. We can add new constants or delete existing ones.
  
  The Fields section of the editor shows the fields with access modifiers that we can modify.
  
  The last section of the editor section is the Methods section, which lists all the class methods with their names, access modifiers, and return types, which are all editable and we can change them.
  

• After all modifications, we File > Savesave the class file using the menu item. We can also File > Export to XMLexport all items such as field names, constants, methods and their values ​​to an XML file using the menu item.