What is layout manager? Describe use of flow layout and grid layout with the help of program code.

 Layout Manager: The Layout managers enable us to control the way in which visual components are arranged in the GUI forms by determining the size and position of components within the containers.

Java – Flow Layout

Flow layout is the default layout, which means if you don’t set any layout in your code then layout would be set to Flow by default. Flow layout puts components (such as text fields, buttons, labels etc) in a row, if horizontal space is not enough to hold all components then Flow layout adds them in a next row and so on.

Example: Here is the image of a Frame where eight buttons have been added to a Frame under Flow layout. As you can see buttons 7 & 8 are in second row because first six buttons consumed all horizontal space.

Points to Note:

• All rows in Flow layout are center aligned by default. As you can see in the above image that buttons 7 & 8 are in center. However we can set the alignment to left or right, we will learn about it later in this post.
• The default horizontal and vertical gap between components is 5 pixels.
• By default the components Orientation is left to right, which means the components would be added from left to right, however we can change it to right to left as well, we will see that later in this post.

Simple Flow Layout Example

The image shown above is the output of this code. Here we are adding 8 buttons to a Frame and layout is being set to FlowLayout.

import java.awt.*;
public class FlowLayoutDemo extends Frame{
    // constructor
    public FlowLayoutDemo(String title)
    {   
        /* It would create the Frame by calling
         * the constructor of Frame class.
         */
        super(title);    
        
        //Setting up Flow Layout
        setLayout(new FlowLayout());
        
        //Creating a button and adding it to the frame
        Button b1 = new Button("Button:1");
        add(b1);
        
        /* Adding other components to the Frame
         */
        Button b2 = new Button("Button:2");
        add(b2);
        
        Button b3 = new Button("Button:3");
        add(b3);
        
        Button b4 = new Button("Button:4");
        add(b4);
        
        Button b5 = new Button("Button:5");
        add(b5);
        
        Button b6 = new Button("Button:6");
        add(b6);
        
        Button b7 = new Button("Button:7");
        add(b7);
        
        Button b8 = new Button("Button:8");
        add(b8);
    }
    public static void main(String[] args)
    {   FlowLayoutDemo screen = 
            new FlowLayoutDemo("Flow Layout - Beginnersbook.com");
        screen.setSize(400,150);
        screen.setVisible(true);
    }
}

Flow Layout where Orientation is right to left

The default Orientation for flow layout is left to right, however we can set it to right to left if want.

import java.awt.*;
public class FlowLayoutDemo extends Frame{
    // constructor
    public FlowLayoutDemo(String title)
    {   
        /* It would create the Frame by calling
         * the constructor of Frame class.
         */
        super(title);    
        
        //Setting up Flow Layout
        setLayout(new FlowLayout());
        
        //Creating a button and adding it to the frame
        Button b1 = new Button("Button:1");
        add(b1);
        
        /* Adding other components to the Frame
         */
        Button b2 = new Button("Button:2");
        add(b2);
        
        Button b3 = new Button("Button:3");
        add(b3);
        
        Button b4 = new Button("Button:4");
        add(b4);
        
        Button b5 = new Button("Button:5");
        add(b5);
        
        Button b6 = new Button("Button:6");
        add(b6);
        
        Button b7 = new Button("Button:7");
        add(b7);
        
        Button b8 = new Button("Button:8");
        add(b8);
        /* This would set the Orientation to 
         *  RightToLeft
         */
        setComponentOrientation(
                ComponentOrientation.RIGHT_TO_LEFT);
        
    }
    public static void main(String[] args)
    {   FlowLayoutDemo screen = 
            new FlowLayoutDemo("Flow Layout - Beginnersbook.com");
        screen.setSize(400,150);
        screen.setVisible(true);
    }
}