Layout Management

/**
 * A very flexible layout manager for Swing containers.
 * Implements LayoutManager2 and Externalizable for full Swing integration.
 */
public class MigLayout implements LayoutManager2, Externalizable {
    
    /** Constructor with no constraints. */
    public MigLayout();
    
    /** 
     * Constructor with layout constraints only.
     * @param layoutConstraints The constraints that concern the whole layout. null will be treated as "".
     */
    public MigLayout(String layoutConstraints);
    
    /**
     * Constructor with layout and column constraints.
     * @param layoutConstraints The constraints that concern the whole layout. null will be treated as "".
     * @param colConstraints The constraints for the columns in the grid. null will be treated as "".
     */
    public MigLayout(String layoutConstraints, String colConstraints);
    
    /**
     * Constructor with all string constraints.
     * @param layoutConstraints The constraints that concern the whole layout. null will be treated as "".
     * @param colConstraints The constraints for the columns in the grid. null will be treated as "".
     * @param rowConstraints The constraints for the rows in the grid. null will be treated as "".
     */
    public MigLayout(String layoutConstraints, String colConstraints, String rowConstraints);
    
    /**
     * Constructor with LC object.
     * @param layoutConstraints The constraints that concern the whole layout. null will be treated as an empty constraint.
     */
    public MigLayout(LC layoutConstraints);
    
    /**
     * Constructor with LC and AC objects.
     * @param layoutConstraints The constraints that concern the whole layout. null will be treated as an empty constraint.
     * @param colConstraints The constraints for the columns in the grid. null will be treated as an empty constraint.
     */
    public MigLayout(LC layoutConstraints, AC colConstraints);
    
    /**
     * Constructor with all constraint objects.
     * @param layoutConstraints The constraints that concern the whole layout. null will be treated as an empty constraint.
     * @param colConstraints The constraints for the columns in the grid. null will be treated as an empty constraint.
     * @param rowConstraints The constraints for the rows in the grid. null will be treated as an empty constraint.
     */
    public MigLayout(LC layoutConstraints, AC colConstraints, AC rowConstraints);
}

import net.miginfocom.swing.MigLayout;
import net.miginfocom.layout.LC;
import net.miginfocom.layout.AC;
import javax.swing.*;

// String-based approach
MigLayout stringLayout = new MigLayout(
    "wrap 3, insets 10",  // Layout constraints
    "[grow][100:100:150][grow]",  // Column constraints  
    "[]10[]"  // Row constraints
);

// Programmatic approach
LC layoutConstraints = new LC()
    .wrapAfter(3)
    .insets("10");
AC colConstraints = new AC()
    .grow()
    .size("100:100:150")
    .grow();
AC rowConstraints = new AC()
    .gap("10");
    
MigLayout programmaticLayout = new MigLayout(layoutConstraints, colConstraints, rowConstraints);

// Apply to container
JPanel panel = new JPanel(stringLayout);

/**
 * Returns layout constraints either as a String or LC depending what was sent in to the constructor.
 * @return The layout constraints either as a String or LC. Never null.
 */
public Object getLayoutConstraints();

/**
 * Sets the layout constraints for the layout manager instance.
 * @param constr The layout constraints as a String or LC representation. null is converted to "" for storage.
 * @throws RuntimeException if the constraint was not valid.
 */
public void setLayoutConstraints(Object constr);

/**
 * Returns the column layout constraints either as a String or AC.
 * @return The column constraints either as a String or AC. Never null.
 */
public Object getColumnConstraints();

/**
 * Sets the column layout constraints for the layout manager instance.
 * @param constr The column layout constraints as a String or AC representation. null is converted to "" for storage.
 * @throws RuntimeException if the constraint was not valid.
 */
public void setColumnConstraints(Object constr);

/**
 * Returns the row layout constraints either as a String or AC.
 * @return The row constraints either as a String or AC. Never null.
 */
public Object getRowConstraints();

/**
 * Sets the row layout constraints for the layout manager instance.
 * @param constr The row layout constraints as a String or AC representation. null is converted to "" for storage.
 * @throws RuntimeException if the constraint was not valid.
 */
public void setRowConstraints(Object constr);

/**
 * Returns a shallow copy of the constraints map.
 * @return A shallow copy of the constraints map. Never null.
 */
public Map<Component, Object> getConstraintMap();

/**
 * Sets the constraints map.
 * @param map The map. Will be copied.
 */
public void setConstraintMap(Map<Component, Object> map);

/**
 * Returns the component constraints as a String representation.
 * @param comp The component to return the constraints for.
 * @return The component constraints as a String representation or null if the component is not registered.
 * The returned values is either a String or a CC depending on what constraint was sent in when the component was added.
 */
public Object getComponentConstraints(Component comp);

/**
 * Sets the component constraint for the component that already must be handled by this layout manager.
 * @param comp The component to set the constraints for.
 * @param constr The component constraints as a String or CC. null is ok.
 * @throws RuntimeException if the constraint was not valid.
 * @throws IllegalArgumentException If the component is not handling the component.
 */
public void setComponentConstraints(Component comp, Object constr);

/**
 * Returns if this layout manager is currently managing this component.
 * @param c The component to check. If null then false will be returned.
 * @return If this layout manager is currently managing this component.
 */
public boolean isManagingComponent(Component c);

/**
 * Adds the callback function that will be called at different stages of the layout cycle.
 * @param callback The callback. Not null.
 */
public void addLayoutCallback(LayoutCallback callback);

/**
 * Removes the callback if it exists.
 * @param callback The callback. May be null.
 */
public void removeLayoutCallback(LayoutCallback callback);

/**
 * Performs layout of the container.
 * @param parent The container to lay out.
 */
public void layoutContainer(Container parent);

/**
 * Returns the minimum layout size.
 * @param parent The container to calculate minimum size for.
 * @return The minimum dimension.
 */
public Dimension minimumLayoutSize(Container parent);

/**
 * Returns the preferred layout size.
 * @param parent The container to calculate preferred size for.
 * @return The preferred dimension.
 */
public Dimension preferredLayoutSize(Container parent);

/**
 * Returns the maximum layout size.
 * @param parent The container to calculate maximum size for.
 * @return The maximum dimension (Integer.MAX_VALUE for both width and height).
 */
public Dimension maximumLayoutSize(Container parent);

/**
 * Returns the alignment along the X axis.
 * @param parent The container.
 * @return The X axis alignment.
 */
public float getLayoutAlignmentX(Container parent);

/**
 * Returns the alignment along the Y axis.
 * @param parent The container.
 * @return The Y axis alignment.
 */
public float getLayoutAlignmentY(Container parent);

/**
 * Adds a component to the layout with string constraint.
 * @param s The constraint string.
 * @param comp The component to add.
 */
public void addLayoutComponent(String s, Component comp);

/**
 * Adds a component to the layout with object constraint.
 * @param comp The component to add.
 * @param constraints The constraint object (String or CC).
 */
public void addLayoutComponent(Component comp, Object constraints);

/**
 * Removes a component from the layout.
 * @param comp The component to remove.
 */
public void removeLayoutComponent(Component comp);

/**
 * Invalidates the layout cache.
 * @param target The container target.
 */
public void invalidateLayout(Container target);

/**
 * Finds parent component of specific type in the component hierarchy.
 * @param clazz The class type to find.
 * @param comp The starting component.
 * @return The parent component of the specified type, or null if not found.
 */
public static <E> E findType(Class<E> clazz, Component comp);

/**
 * Reads the object state from the input stream for deserialization.
 * @param in The ObjectInput to read from
 * @throws IOException if I/O error occurs
 * @throws ClassNotFoundException if class cannot be found during deserialization
 */
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException;

/**
 * Writes the object state to the output stream for serialization.
 * @param out The ObjectOutput to write to
 * @throws IOException if I/O error occurs
 */
public void writeExternal(ObjectOutput out) throws IOException;

import net.miginfocom.swing.MigLayout;
import javax.swing.*;
import java.awt.*;

// Dynamic constraint modification
MigLayout layout = new MigLayout("wrap 2");
JPanel panel = new JPanel(layout);

JButton button = new JButton("Click me");
panel.add(button, "growx");

// Later modify constraints
layout.setComponentConstraints(button, "growx, span 2");

// Check if component is managed
if (layout.isManagingComponent(button)) {
    // Component is managed by this layout
    Object constraints = layout.getComponentConstraints(button);
}

// Find parent window
Window parentWindow = MigLayout.findType(Window.class, button);

// Serialization support
try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("layout.ser"))) {
    layout.writeExternal(out);
}

try (ObjectInputStream in = new ObjectInputStream(new FileInputStream("layout.ser"))) {
    MigLayout restoredLayout = new MigLayout();
    restoredLayout.readExternal(in);
}