Java tutorial
/* * * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved. * * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use, * modify and redistribute this software in source and binary code form, * provided that i) this copyright notice and license appear on all copies of * the software; and ii) Licensee does not utilize the software in a manner * which is disparaging to Sun. * * This software is provided "AS IS," without a warranty of any kind. ALL * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE * POSSIBILITY OF SUCH DAMAGES. * * This software is not designed or intended for use in on-line control of * aircraft, air traffic, aircraft navigation or aircraft communications; or in * the design, construction, operation or maintenance of any nuclear * facility. Licensee represents and warrants that it will not use or * redistribute the Software for such purposes. */ /* * A 1.4 application that uses SpringLayout to create a single row * of components, similar to that produced by a horizontal BoxLayout. * Other files required: SpringUtilities.java. */ import javax.swing.*; import java.awt.*; public class SpringBox { /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event-dispatching thread. */ private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("SpringBox"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Set up the content pane. Container contentPane = frame.getContentPane(); contentPane.setLayout(new SpringLayout()); //Add the buttons. contentPane.add(new JButton("Button 1")); contentPane.add(new JButton("Button 2")); contentPane.add(new JButton("Button 3")); contentPane.add(new JButton("Long-Named Button 4")); contentPane.add(new JButton("5")); //Lay out the buttons in one row and as many columns //as necessary, with 6 pixels of padding all around. SpringUtilities.makeCompactGrid(contentPane, 1, contentPane.getComponentCount(), 6, 6, 6, 6); //Display the window. frame.pack(); frame.setVisible(true); } public static void main(String[] args) { //Schedule a job for the event-dispatching thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } class SpringUtilities { /** * A debugging utility that prints to stdout the component's minimum, * preferred, and maximum sizes. */ public static void printSizes(Component c) { System.out.println("minimumSize = " + c.getMinimumSize()); System.out.println("preferredSize = " + c.getPreferredSize()); System.out.println("maximumSize = " + c.getMaximumSize()); } /** * Aligns the first <code>rows</code> * <code>cols</code> components of * <code>parent</code> in a grid. Each component is as big as the maximum * preferred width and height of the components. The parent is made just big * enough to fit them all. * * @param rows * number of rows * @param cols * number of columns * @param initialX * x location to start the grid at * @param initialY * y location to start the grid at * @param xPad * x padding between cells * @param yPad * y padding between cells */ public static void makeGrid(Container parent, int rows, int cols, int initialX, int initialY, int xPad, int yPad) { SpringLayout layout; try { layout = (SpringLayout) parent.getLayout(); } catch (ClassCastException exc) { System.err.println("The first argument to makeGrid must use SpringLayout."); return; } Spring xPadSpring = Spring.constant(xPad); Spring yPadSpring = Spring.constant(yPad); Spring initialXSpring = Spring.constant(initialX); Spring initialYSpring = Spring.constant(initialY); int max = rows * cols; // Calculate Springs that are the max of the width/height so that all // cells have the same size. Spring maxWidthSpring = layout.getConstraints(parent.getComponent(0)).getWidth(); Spring maxHeightSpring = layout.getConstraints(parent.getComponent(0)).getWidth(); for (int i = 1; i < max; i++) { SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i)); maxWidthSpring = Spring.max(maxWidthSpring, cons.getWidth()); maxHeightSpring = Spring.max(maxHeightSpring, cons.getHeight()); } // Apply the new width/height Spring. This forces all the // components to have the same size. for (int i = 0; i < max; i++) { SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i)); cons.setWidth(maxWidthSpring); cons.setHeight(maxHeightSpring); } // Then adjust the x/y constraints of all the cells so that they // are aligned in a grid. SpringLayout.Constraints lastCons = null; SpringLayout.Constraints lastRowCons = null; for (int i = 0; i < max; i++) { SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i)); if (i % cols == 0) { // start of new row lastRowCons = lastCons; cons.setX(initialXSpring); } else { // x position depends on previous component cons.setX(Spring.sum(lastCons.getConstraint(SpringLayout.EAST), xPadSpring)); } if (i / cols == 0) { // first row cons.setY(initialYSpring); } else { // y position depends on previous row cons.setY(Spring.sum(lastRowCons.getConstraint(SpringLayout.SOUTH), yPadSpring)); } lastCons = cons; } // Set the parent's size. SpringLayout.Constraints pCons = layout.getConstraints(parent); pCons.setConstraint(SpringLayout.SOUTH, Spring.sum(Spring.constant(yPad), lastCons.getConstraint(SpringLayout.SOUTH))); pCons.setConstraint(SpringLayout.EAST, Spring.sum(Spring.constant(xPad), lastCons.getConstraint(SpringLayout.EAST))); } /* Used by makeCompactGrid. */ private static SpringLayout.Constraints getConstraintsForCell(int row, int col, Container parent, int cols) { SpringLayout layout = (SpringLayout) parent.getLayout(); Component c = parent.getComponent(row * cols + col); return layout.getConstraints(c); } /** * Aligns the first <code>rows</code> * <code>cols</code> components of * <code>parent</code> in a grid. Each component in a column is as wide as * the maximum preferred width of the components in that column; height is * similarly determined for each row. The parent is made just big enough to * fit them all. * * @param rows * number of rows * @param cols * number of columns * @param initialX * x location to start the grid at * @param initialY * y location to start the grid at * @param xPad * x padding between cells * @param yPad * y padding between cells */ public static void makeCompactGrid(Container parent, int rows, int cols, int initialX, int initialY, int xPad, int yPad) { SpringLayout layout; try { layout = (SpringLayout) parent.getLayout(); } catch (ClassCastException exc) { System.err.println("The first argument to makeCompactGrid must use SpringLayout."); return; } // Align all cells in each column and make them the same width. Spring x = Spring.constant(initialX); for (int c = 0; c < cols; c++) { Spring width = Spring.constant(0); for (int r = 0; r < rows; r++) { width = Spring.max(width, getConstraintsForCell(r, c, parent, cols).getWidth()); } for (int r = 0; r < rows; r++) { SpringLayout.Constraints constraints = getConstraintsForCell(r, c, parent, cols); constraints.setX(x); constraints.setWidth(width); } x = Spring.sum(x, Spring.sum(width, Spring.constant(xPad))); } // Align all cells in each row and make them the same height. Spring y = Spring.constant(initialY); for (int r = 0; r < rows; r++) { Spring height = Spring.constant(0); for (int c = 0; c < cols; c++) { height = Spring.max(height, getConstraintsForCell(r, c, parent, cols).getHeight()); } for (int c = 0; c < cols; c++) { SpringLayout.Constraints constraints = getConstraintsForCell(r, c, parent, cols); constraints.setY(y); constraints.setHeight(height); } y = Spring.sum(y, Spring.sum(height, Spring.constant(yPad))); } // Set the parent's size. SpringLayout.Constraints pCons = layout.getConstraints(parent); pCons.setConstraint(SpringLayout.SOUTH, y); pCons.setConstraint(SpringLayout.EAST, x); } }