Both JFrame and JPanel are classes used in Java. The latter is a programming language that is object-oriented and class-based. It is a digital platform used for creating and developing applications. Java was developed by Sun Microsystems specifically for the Internet in 1995. Its main objective is to develop programs that can run in all forms of computing devices like PCs, Laptops, smartphones etc.
JPanel vs JFrame
The main difference between JPanel and JFrame is that JPanel refers to a space where different types of visuals e.g. pictures, texts or figures and controls like text-fields, buttons etc. can become visible. JFrame represents an independent window with its unique characteristics.
JPanel is a broad purpose container that is used for putting in a set of more complex components or operations. It represents a space where one can see various controls such as check-boxes, buttons and text-fields as well as visuals like pictures and texts.
JFrame on the other hand, is the basic container which is used for storing in components like buttons, labels and text fields. However, unlike a JPanel, a JFrame also contains a title bar.
Comparison Table Between JPanel and JFrame (in Tabular Form)
| Parameters of Comparison | JPanel | JFrame |
|---|---|---|
| Parent class | javax.swing.JComponent | java.awt.Frame |
| What is it? | A specific area for putting in GUI components and operations. | A window for developing independent GUI applications. |
| Title Bar | There is no title bar. | It contains a title bar. |
| Weight | Light | Heavy |
| Can contain | Multiple GUI components and operations. | Multiple frames and JPanels. |
What is JPanel?
It refers to a general container used to assemble a group of components in synchronization. It is quite an uncomplicated component which usually does not possess a graphical user interface (GUI). However, it may have a GUI if it is laid out in an opaque background or contains a display border.
The JPanel container class is found in the javax.swing package. The swing is an extension of the Abstract Window Toolkit (AWT) which is the first generation of Java Application Programming Interface (API). The former enhances the serviceability of the latter.
The JPanel is a very simple and lightweight container which is a subclass of the java.swing.JComponent class. The JComponent in turn is a subclass of the container. Consequently, several methods used for the JPanel are derived from its superclasses. Some of the examples of such methods include image observer, alignments and accessibility.
The JPanel enables one to place checkboxes, buttons, images, fields, labels and even texts into it. It s mainly defined as an area where controls and visuals can be placed in.
To use a JPanel, one needs to first create its object which is done by calling for a constructor JPanel (). Following this invocation, a blank panel is generated. It looks grim by default but its background colour can be changed by invoking the appropriate methods of JPanel class. The components of the blank panel are customisable.
For that one needs to use the Layout managers. There are a variety of Layout managers such as Border Layout, Grid Layout and Flow Layout and so on. These Layout managers enable one to adjust the positions, sizes and alignment of the components that have been put up into the JPanel. The colours of the components can also be customized using constructors like setForeGround(color_obj), setColor(color_obj) and setBackgroundColor(color_obj).
What is JFrame?
It is the base or foundation container used for creating independent GUI applications. It appears and runs like a window such as a notification window or a warning window that normally pops up on computer screens.
Just like JPanel, it is also part of the swing toolkit but its parent class is Java.awt.Frame. That is to say, it is an extended version of the Frame found in Java Abstract Window Toolkit (AWT), the oldest generation of Java API. What makes JFrame better than Frame is that it provides the option for closing or hiding the window by using the setDefaultCloseOperation(int) method.
It possesses its constructors and methods which are used to place components like text fields, buttons, borders, title bar etc. inside it and customise its physical features like fonts, size, colours and alignments and so on. Each feature has its unique syntax used for customisation.
It has two sub-divisions, namely menu bar and content pane. The components of JFrame are known as contents and most of the contents are found in the content pane. Besides, to add content in the JFrame, one needs to put it in the content pane.
JFrame employs a method of windows listener that starts working whenever a person carries out operations like activating, closing, opening, minimizing or maximizing a window. It also employs a mouse listener so that the frame can react to the actions of the mouse.
A JFrame can place inside itself multiple frames and JPanels but all of them depend on the mainframe for their existence. A large number of functions can be created for the JFrame by using not only the methods of Listeners but also the methods of get, set and add methods.
Main Differences Between JPanel and JFrame
- Both JPanel and JFrame are container classes. But the parent of the former is javax.swing.JComponent class. While the latter is the child of java.awt.Frame class.
- In terms of weight, JFrame is heavy and is employed as a top-level window. While JPanel is light and is used for organising Graphical User Interface (GUI) components.
- JFrame is a window used for creating independent GUI applications. While Jpanel is a space where one can put together a group of complex components or operations.
- Being a window, JFrame contains a title bar. While Jpanel does not contain a title bar.
- JFrame can contain within itself multiple frames and JPanels. But JPanel cannot contain within itself JFrames. However, it can place within itself multiple operations.
Conclusion
In Java (an object-oriented programming language) there are different types of classes which serve as the framework or design for the creation of objects or a specific data structure, retaining the instance variables of the objects and consequently, maintaining their state and application of the behavioural patterns of the objects.
Among these classes, JPanel and JFrame constitute two different classes used in writing Graphical User Interface (GUI) applications. These classes are mainly concerned with the ‘view’ of an application and even though they may pop up as a window when run, one can very well distinguish between them as a JPanel does not contain a title bar while a JFrame does.
References
- https://docs.oracle.com/javase/7/docs/api/javax/swing/JFrame.html