What Is the default output of the "javap" Command?

The default output of the "javap" command presents the interface information of the Java class stored in the given bytecode.

1. Create a Java class, HelloWorldFrame.java, with the following source code,

import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class HelloWorldFrame extends JFrame {
  String message = "Hello World!";

  public HelloWorldFrame(){
    setContentPane(new JPanel(){
      @Override
      protected void paintComponent(Graphics g) {
        g.drawString(message, 15, 30);
      }
    });
    setSize(100, 100);
  }
  public static void main(String[] args) {
    HelloWorldFrame frame = new HelloWorldFrame();
    frame.setVisible(true);
  }
}

2. Compile it into a bytecode file, HelloWorldFrame.class:

> javac HelloWorldFrame.java 

3. Disassemble it using "javap" command with default options

> javap HelloWorldFrame.class 

Compiled from "HelloWorldFrame.java"
public class HelloWorldFrame extends javax.swing.JFrame {
  java.lang.String message;
  public HelloWorldFrame();
  public static void main(java.lang.String[]);
}

 

⇒ "javap -c" - Generate Assembler Instructions

⇐ What Is JDK "javap" Command

⇑ JDK "javap" Command

⇑⇑ Java Bytecode Tools