SpringLayout – Java Swing – Example

In this tutorial, we are going to see an example of SpringLayout in Java Swing. SpringLayout organizes the elements of its associated container according to a set of constraints. Constraints are nothing more than horizontal and vertical distance between two components. All constraints are represented by a SpringLayout.Constraint object.

Each element of a SpringLayout container, as well as the container itself, has exactly one set of constraints associated with it.

Each edge position depends on the position of the other edge. If a constraint is added to create a new edge, the previous binding is removed. SpringLayout does not automatically define the location of the components it manages.
 

SpringLayout class constructor:

• SpringLayout(): used to build a new SpringLayout class.

 

Commonly used methods of SpringLayout:

• addLayoutComponent(Component c, Object obj): If the constraints are an instance of SpringLayout.Constraints, associate the constraints to the specified component.
• getLayoutAlignmentX(Container c): used to return 0.5f (centered).
• getLayoutAlignmentY(Container c): used to return 0.5f (centered).
• getConstraint((String str, Component c): returns the spring controlling the distance between the specified edge of the component and the top or left edge of its parent.
• getConstraint(Component c): returns the constraints of the specified component.
• layoutContainer(Container parent): used to arrange the specified container.

 

Example of SpringLayout in Java Swing:

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

public class Main 
{
  public static void main(String args[]) 
  {
    JFrame f = new JFrame("SpringLayout Example");
  
    Container content = f.getContentPane();

    SpringLayout layout = new SpringLayout();
    content.setLayout(layout);

    Component lab = new JLabel("Label :");
    Component text = new JTextField(15);

    content.add(lab);
    content.add(text);
    layout.putConstraint(SpringLayout.WEST, lab, 20, SpringLayout.WEST, content);
    layout.putConstraint(SpringLayout.NORTH, lab, 20, SpringLayout.NORTH, content);
    layout.putConstraint(SpringLayout.NORTH, text, 20, SpringLayout.NORTH, content);
    layout.putConstraint(SpringLayout.WEST, text, 20, SpringLayout.EAST, lab);

    f.setSize(300, 100);
    f.setVisible(true);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}

Output:

MCQPractice competitive and technical Multiple Choice Questions and Answers (MCQs) with simple and logical explanations to prepare for tests and interviews.Read More