SWING - SpringLayout Class

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Introduction

The class SpringLayout positions the children of its associated container according to a set of constraints.

Class Declaration

Following is the declaration for javax.swing.SpringLayout class −

public class SpringLayout
   extends Object
      implements LayoutManager2

Field

Following are the fields for javax.swing.SpringLayout class −

• static String BASELINE − Specifies the baseline of a component.

• static String EAST − Specifies the right edge of a component's bounding rectangle.

• static String HEIGHT − Specifies the height of a component's bounding rectangle.

• static String HORIZONTAL_CENTER − Specifies the horizontal center of a component's bounding rectangle.

• static String NORTH − Specifies the top edge of a component's bounding rectangle.

• static String SOUTH − Specifies the bottom edge of a component's bounding rectangle.

• static String VERTICAL_CENTER − Specifies the vertical center of a component's bounding rectangle.

• static String WEST − Specifies the left edge of a component's bounding rectangle.

• static String WIDTH − Specifies the width of a component's bounding rectangle.

Class Constructors

Sr.No.	Constructor & Description
1	SpringLayout() Creates a new SpringLayout.

Class Methods

Sr.No.	Method & Description
1	void addLayoutComponent(Component component, Object constraints) If constraints is an instance of SpringLayout.Constraints, associates the constraints with the specified component.
2	void addLayoutComponent(String name, Component c) Has no effect, since this layout manager does not use a per-component string.
3	Spring getConstraint(String edgeName, Component c) Returns the spring controlling the distance between the specified edge of the component and the top or left edge of its parent.
4	SpringLayout.Constraints getConstraints(Component c) Returns the constraints for the specified component.
5	float getLayoutAlignmentX(Container p) Returns 0.5f (centered).
6	float getLayoutAlignmentY(Container p) Returns 0.5f (centered).
7	void invalidateLayout(Container p) Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.
8	void layoutContainer(Container parent) Lays out the specified container.
9	Dimension maximumLayoutSize(Container parent) Calculates the maximum size dimensions for the specified container, given the components it contains.
10	Dimension minimumLayoutSize(Container parent) Calculates the minimum size dimensions for the specified container, given the components it contains.
11	Dimension preferredLayoutSize(Container parent) Calculates the preferred size dimensions for the specified container, given the components it contains.
12	void putConstraint(String e1, Component c1, int pad, String e2, Component c2) Links edge e1 of component c1 to edge e2 of component c2, with a fixed distance between the edges.
13	void putConstraint(String e1, Component c1, Spring s, String e2, Component c2) Links edge e1 of component c1 to edge e2 of component c2.
14	void removeLayoutComponent(Component c) Removes the constraints associated with the specified component.

Methods Inherited

This class inherits methods from the following class −

• java.lang.Object

SpringLayout Example

Create the following Java program using any editor of your choice in say D:/ > SWING > com > tutorialspoint > gui >

SwingLayoutDemo.java

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

public class SwingSpringLayout {
   private JFrame mainFrame;
   private JLabel headerLabel;
   private JLabel statusLabel;
   private JPanel controlPanel;

   public SwingSpringLayout(){
      prepareGUI();
   }
   public static void main(String[] args){
      SwingSpringLayout swingLayoutDemo = new SwingSpringLayout();  
      swingLayoutDemo.showSpringLayoutDemo();       
   }
   private void prepareGUI(){
      mainFrame = new JFrame("Java SWING Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));

      headerLabel = new JLabel("",JLabel.CENTER );
      statusLabel = new JLabel("",JLabel.CENTER);        
      statusLabel.setSize(350,100);
      
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });
		controlPanel = new JPanel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }
   private void showSpringLayoutDemo(){
      headerLabel.setText("Layout in action: SpringLayout");   
      SpringLayout layout = new SpringLayout();

      JPanel panel = new JPanel();
      panel.setLayout(layout);
      JLabel label = new JLabel("Enter Name: ");
      JTextField textField = new JTextField("", 15);
      panel.add(label);
      panel.add(textField);

      layout.putConstraint(SpringLayout.WEST, label,5, SpringLayout.WEST, controlPanel);
      layout.putConstraint(SpringLayout.NORTH, label,5, SpringLayout.NORTH, controlPanel);
      layout.putConstraint(SpringLayout.WEST, textField,5, SpringLayout.EAST, label);
      layout.putConstraint(SpringLayout.NORTH, textField,5, SpringLayout.NORTH, 
         controlPanel);
      
      layout.putConstraint(SpringLayout.EAST, panel,5, SpringLayout.EAST, textField);
      layout.putConstraint(SpringLayout.SOUTH, panel,5, SpringLayout.SOUTH, textField);
      controlPanel.add(panel);
      mainFrame.setVisible(true);  
   } 
}

Compile the program using the command prompt. Go to D:/ > SWING and type the following command.

D:\SWING>javac com\tutorialspoint\gui\SwingLayoutDemo.java

If no error occurs, it means the compilation is successful. Run the program using the following command.

D:\SWING>java com.tutorialspoint.gui.SwingLayoutDemo

Verify the following output.