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Creating a JPanel

Constructor Purpose

JPanel()

JPanel(LayoutManager)

Creates a panel. The

LayoutManager parameter

provides a layout manager for the

new panel. By default, a panel uses a

FlowLayout to lay out its

components.

Managing a Container's Components

Method Purpose

void add(Component)

void add(Component, int)

void add(Component,

Object)

Adds the specified component

to the panel.

When present, the int

parameter is the index of the

component within the

container. By default, the first

component added is at index 0,

the second is at index 1, and so

on.

The Object parameter is

layout manager dependent and

typically provides information to

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void add(Component,

Object, int)

void add(String,

Component)

the layout manager regarding

positioning and other layout

constraints for the added

component.

The String parameter is

similar to the Object

parameter.

int getComponentCount()

Gets the number of components

in this panel.

Component

getComponent(int)

Component

getComponentAt(int, int)

Component

getComponentAt(Point)

Component[]

getComponents()

Gets the specified component or

components. You can get a

component based on its index or

x, yposition.

void remove(Component)

void remove(int)

void removeAll()

Removes the specified

component(s).

Setting or Getting the LayoutManager

Method Purpose

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void

setLayout(LayoutManager)

LayoutManager

getLayout()

Sets or gets the layout manager

for this panel. The layout

manager is responsible for

positioning the panel'scomponents within the panel's

bounds according to some

philosophy.

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.Font;import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JPanel;

/**

* A component subclass that demonstrates

nested containers and components. It

* creates the hierarchy shown below, and

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uses different colors to distinguish

* the different nesting levels of the co

ntainers

*

* Containers---panel1----button1 | |---

panel2----button2 | |

* |----panel3----button3 | |------

panel4----button4 | |----button5 |---

button6

*/

public c

lassConta

i

nersex

tends

JPanel {public Containers() {

this.setBackground(Color.white); // T

his component is white

this.setFont(newFont("Dialog", Font.

BOLD, 24));

JPanel p1 =new

JPanel();p1.setBackground(newColor(200, 200,

200)); // Panel1 is darker

this.add(p1); // p1 is contained by t

his component

p1.add(newJButton("#1")); // Button

1 is contained in p1

JPanel p2 = newJPanel();

p2.setBackground(newColor(150, 150,

150)); // p2 is darker than p2

p1.add(p2); // p2 is contained in p1

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p2.add(newJButton("#2")); // Button

2 is contained in p2

JPanel p3 = newJPanel();

p3.setBackground(newColor(100, 100,

100)); // p3 is darker than p2

p2.add(p3); // p3 is contained in p2

p3.add(newJButton("#3")); // Button

3 is contained in p3

JPanel p4 =new

JPanel();p4.setBackground(newColor(150, 150,

150)); // p4 is darker than p1

p1.add(p4); // p4 is contained in p1

p4.add(newJButton("#4")); // Button4

is contained in p4

p4.add(newJButton("#5")); // Button5

is also conta

ined

in p4

this.add(newJButton("#6")); // Butto

n6 is contained in this component

}

public static voidmain(String[] args)

{JFrame frame = newJFrame();

frame.addWindowListener(newWindowAda

pter() {

public voidwindowClosing(WindowEve

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nt e) {

System.exit(0);

}

});

frame.getContentPane().add(newContai

ners(), BorderLayout.CENTER);

// Finally, set the size of the main

window, and pop it up.

frame.setSize(600, 400);

f

rame.setVi

si

ble(true

);}

}