Java GridLayout - Decodejava.com

GridLayout Manager

GridLayout manager is used to position the components in the manner of rows and columns.

Constructors of GridLayout

Constructor	Description
public GridLayout()	Creates a GridLayout with single column to hold the components.
*public GridLayout(int rows, int columns)*	Creates a GridLayout with a specified number of rows and columns to hold the components.
*public GridLayout(int rows, int columns, int horizontalSpace, int verticalSpace)*	Creates a GridLayout with a specified number of rows and columns to hold the components and also lets you specify the horizontal and vertical space between the components.

GridLayout methods

Methods	Description
public void add(Component comp)	This method adds the component, comp, to the container
public void setLayout(LayoutManager object)	This method sets the layout of the components in a container.
public void setHgap(int horizontalGap)	This method sets the horizontal space betwen components.
public void setVgap(int verticalGap)	This method sets the vertical space betwen components.

LayoutManager is an interface which is implemented by GridLayout manager class.

An example display the use of GridLayout Manager.

In the upcoming code, we have going to create 16 buttons that will be positioned across the 4 rows and 4 columns of the container, JFrame.
We will call setLayout() method of JFrame class and pass it the object of GridLayout class, to set the position of the 16 buttons, as per the positioning defined by GridLayout.
Next, we will add each button to the container, JFrame by calling its add() method.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class GridLayoutEx 
{
public static void main(String... ar)
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
new A();
}
});

}//Closing the main method
}//Closing the class A


class A 
{
JFrame jf;


A()
{
jf = new JFrame("GridLayout Example");

JButton button1 = new JButton("1");
JButton button2 = new JButton("2");
JButton button3 = new JButton("3");
JButton button4 = new JButton("x");

JButton button5 = new JButton("4");
JButton button6 = new JButton("5");
JButton button7 = new JButton("6");
JButton button8 = new JButton("-");

JButton button9 = new JButton("7");
JButton button10 = new JButton("8");
JButton button11 = new JButton("9");
JButton button12 = new JButton("+");


JButton button13 = new JButton("0");
JButton button14 = new JButton(".");
JButton button15 = new JButton("=");
JButton button16 = new JButton("Result");


//Setting the layout of the components in container, JFrame, to GridLayout
jf.setLayout(new GridLayout(4,4)); //GridLayout constructor is called with 4 number of rows
				   //and 4 number of columns, to hold 16 buttons

jf.add(button1);
jf.add(button2);
jf.add(button3);
jf.add(button4);

jf.add(button5);
jf.add(button6);
jf.add(button7);
jf.add(button8);

jf.add(button9);
jf.add(button10);
jf.add(button11);
jf.add(button12);

jf.add(button13);
jf.add(button14);
jf.add(button15);
jf.add(button16);


jf.setSize(300,200);
jf.setVisible(true); 
}

}

When you run the code, you are presented a window that contains all the 16 buttons, positioned across the 4 rows and 4 columns, using GridLayout manager. As you may see in the figure1, the window resembles a mini calculator.

Figure 1

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