* </tr> * </table> * <p> * When both the number of rows and the number of columns have * been set to non-zero values, either by a constructor or * by the <tt>setRows and setColumns methods, the number of * columns specified is ignored. Instead, the number of * columns is determined from the specified number of rows * and the total number of components in the layout. So, for * example, if three rows and two columns have been specified * and nine components are added to the layout, they will * be displayed as three rows of three columns. Specifying * the number of columns affects the layout only when the * number of rows is set to zero. * * @author Arthur van Hoff * @since JDK1.0 */ public class GridLayout implements LayoutManager, java.io.Serializable { /* * serialVersionUID */ private static final long serialVersionUID = -7411804673224730901L; /** * This is the horizontal gap (in pixels) which specifies the space * between columns. They can be changed at any time. * This should be a non-negative integer. * * @serial * @see #getHgap() * @see #setHgap(int) */ int hgap; /** * This is the vertical gap (in pixels) which specifies the space * between rows. They can be changed at any time. * This should be a non negative integer. * * @serial * @see #getVgap() * @see #setVgap(int) */ int vgap; /** * This is the number of rows specified for the grid. The number * of rows can be changed at any time. * This should be a non negative integer, where '0' means * 'any number' meaning that the number of Rows in that * dimension depends on the other dimension. * * @serial * @see #getRows() * @see #setRows(int) */ int rows; /** * This is the number of columns specified for the grid. The number * of columns can be changed at any time. * This should be a non negative integer, where '0' means * 'any number' meaning that the number of Columns in that * dimension depends on the other dimension. * * @serial * @see #getColumns() * @see #setColumns(int) */ int cols; /** * Creates a grid layout with a default of one column per component, * in a single row. * @since JDK1.1 */ public GridLayout() { this(1, 0, 0, 0); } /** * Creates a grid layout with the specified number of rows and * columns. All components in the layout are given equal size. * <p> * One, but not both, of <code>rows and cols can * be zero, which means that any number of objects can be placed in a * row or in a column. * @param rows the rows, with the value zero meaning * any number of rows. * @param cols the columns, with the value zero meaning * any number of columns. */ public GridLayout(int rows, int cols) { this(rows, cols, 0, 0); } /** * Creates a grid layout with the specified number of rows and * columns. All components in the layout are given equal size. * <p> * In addition, the horizontal and vertical gaps are set to the * specified values. Horizontal gaps are placed between each * of the columns. Vertical gaps are placed between each of * the rows. * <p> * One, but not both, of <code>rows and cols can * be zero, which means that any number of objects can be placed in a * row or in a column. * <p> * All <code>GridLayout constructors defer to this one. * @param rows the rows, with the value zero meaning * any number of rows * @param cols the columns, with the value zero meaning * any number of columns * @param hgap the horizontal gap * @param vgap the vertical gap * @exception IllegalArgumentException if the value of both * <code>rows and cols is * set to zero */ public GridLayout(int rows, int cols, int hgap, int vgap) { if ((rows == 0) && (cols == 0)) { throw new IllegalArgumentException("rows and cols cannot both be zero"); } this.rows = rows; this.cols = cols; this.hgap = hgap; this.vgap = vgap; } /** * Gets the number of rows in this layout. * @return the number of rows in this layout * @since JDK1.1 */ public int getRows() { return rows; } /** * Sets the number of rows in this layout to the specified value. * @param rows the number of rows in this layout * @exception IllegalArgumentException if the value of both * <code>rows and cols is set to zero * @since JDK1.1 */ public void setRows(int rows) { if ((rows == 0) && (this.cols == 0)) { throw new IllegalArgumentException("rows and cols cannot both be zero"); } this.rows = rows; } /** * Gets the number of columns in this layout. * @return the number of columns in this layout * @since JDK1.1 */ public int getColumns() { return cols; } /** * Sets the number of columns in this layout to the specified value. * Setting the number of columns has no affect on the layout * if the number of rows specified by a constructor or by * the <tt>setRows method is non-zero. In that case, the number * of columns displayed in the layout is determined by the total * number of components and the number of rows specified. * @param cols the number of columns in this layout * @exception IllegalArgumentException if the value of both * <code>rows and cols is set to zero * @since JDK1.1 */ public void setColumns(int cols) { if ((cols == 0) && (this.rows == 0)) { throw new IllegalArgumentException("rows and cols cannot both be zero"); } this.cols = cols; } /** * Gets the horizontal gap between components. * @return the horizontal gap between components * @since JDK1.1 */ public int getHgap() { return hgap; } /** * Sets the horizontal gap between components to the specified value. * @param hgap the horizontal gap between components * @since JDK1.1 */ public void setHgap(int hgap) { this.hgap = hgap; } /** * Gets the vertical gap between components. * @return the vertical gap between components * @since JDK1.1 */ public int getVgap() { return vgap; } /** * Sets the vertical gap between components to the specified value. * @param vgap the vertical gap between components * @since JDK1.1 */ public void setVgap(int vgap) { this.vgap = vgap; } /** * Adds the specified component with the specified name to the layout. * @param name the name of the component * @param comp the component to be added */ public void addLayoutComponent(String name, Component comp) { } /** * Removes the specified component from the layout. * @param comp the component to be removed */ public void removeLayoutComponent(Component comp) { } /** * Determines the preferred size of the container argument using * this grid layout. * <p> * The preferred width of a grid layout is the largest preferred * width of all of the components in the container times the number of * columns, plus the horizontal padding times the number of columns * minus one, plus the left and right insets of the target container. * <p> * The preferred height of a grid layout is the largest preferred * height of all of the components in the container times the number of * rows, plus the vertical padding times the number of rows minus one, * plus the top and bottom insets of the target container. * * @param parent the container in which to do the layout * @return the preferred dimensions to lay out the * subcomponents of the specified container * @see java.awt.GridLayout#minimumLayoutSize * @see java.awt.Container#getPreferredSize() */ public Dimension preferredLayoutSize(Container parent) { synchronized (parent.getTreeLock()) { Insets insets = parent.getInsets(); int ncomponents = parent.getComponentCount(); int nrows = rows; int ncols = cols; if (nrows > 0) { ncols = (ncomponents + nrows - 1) / nrows; } else { nrows = (ncomponents + ncols - 1) / ncols; } int w = 0; int h = 0; for (int i = 0 ; i < ncomponents ; i++) { Component comp = parent.getComponent(i); Dimension d = comp.getPreferredSize(); if (w < d.width) { w = d.width; } if (h < d.height) { h = d.height; } } return new Dimension(insets.left + insets.right + ncols*w + (ncols-1)*hgap, insets.top + insets.bottom + nrows*h + (nrows-1)*vgap); } } /** * Determines the minimum size of the container argument using this * grid layout. * <p> * The minimum width of a grid layout is the largest minimum width * of all of the components in the container times the number of columns, * plus the horizontal padding times the number of columns minus one, * plus the left and right insets of the target container. * <p> * The minimum height of a grid layout is the largest minimum height * of all of the components in the container times the number of rows, * plus the vertical padding times the number of rows minus one, plus * the top and bottom insets of the target container. * * @param parent the container in which to do the layout * @return the minimum dimensions needed to lay out the * subcomponents of the specified container * @see java.awt.GridLayout#preferredLayoutSize * @see java.awt.Container#doLayout */ public Dimension minimumLayoutSize(Container parent) { synchronized (parent.getTreeLock()) { Insets insets = parent.getInsets(); int ncomponents = parent.getComponentCount(); int nrows = rows; int ncols = cols; if (nrows > 0) { ncols = (ncomponents + nrows - 1) / nrows; } else { nrows = (ncomponents + ncols - 1) / ncols; } int w = 0; int h = 0; for (int i = 0 ; i < ncomponents ; i++) { Component comp = parent.getComponent(i); Dimension d = comp.getMinimumSize(); if (w < d.width) { w = d.width; } if (h < d.height) { h = d.height; } } return new Dimension(insets.left + insets.right + ncols*w + (ncols-1)*hgap, insets.top + insets.bottom + nrows*h + (nrows-1)*vgap); } } /** * Lays out the specified container using this layout. * <p> * This method reshapes the components in the specified target * container in order to satisfy the constraints of the * <code>GridLayout object. * <p> * The grid layout manager determines the size of individual * components by dividing the free space in the container into * equal-sized portions according to the number of rows and columns * in the layout. The container's free space equals the container's * size minus any insets and any specified horizontal or vertical * gap. All components in a grid layout are given the same size. * * @param parent the container in which to do the layout * @see java.awt.Container * @see java.awt.Container#doLayout */ public void layoutContainer(Container parent) { synchronized (parent.getTreeLock()) { Insets insets = parent.getInsets(); int ncomponents = parent.getComponentCount(); int nrows = rows; int ncols = cols; boolean ltr = parent.getComponentOrientation().isLeftToRight(); if (ncomponents == 0) { return; } if (nrows > 0) { ncols = (ncomponents + nrows - 1) / nrows; } else { nrows = (ncomponents + ncols - 1) / ncols; } // 4370316. To position components in the center we should: // 1. get an amount of extra space within Container // 2. incorporate half of that value to the left/top position // Note that we use trancating division for widthOnComponent // The reminder goes to extraWidthAvailable int totalGapsWidth = (ncols - 1) * hgap; int widthWOInsets = parent.width - (insets.left + insets.right); int widthOnComponent = (widthWOInsets - totalGapsWidth) / ncols; int extraWidthAvailable = (widthWOInsets - (widthOnComponent * ncols + totalGapsWidth)) / 2; int totalGapsHeight = (nrows - 1) * vgap; int heightWOInsets = parent.height - (insets.top + insets.bottom); int heightOnComponent = (heightWOInsets - totalGapsHeight) / nrows; int extraHeightAvailable = (heightWOInsets - (heightOnComponent * nrows + totalGapsHeight)) / 2; if (ltr) { for (int c = 0, x = insets.left + extraWidthAvailable; c < ncols ; c++, x += widthOnComponent + hgap) { for (int r = 0, y = insets.top + extraHeightAvailable; r < nrows ; r++, y += heightOnComponent + vgap) { int i = r * ncols + c; if (i < ncomponents) { parent.getComponent(i).setBounds(x, y, widthOnComponent, heightOnComponent); } } } } else { for (int c = 0, x = (parent.width - insets.right - widthOnComponent) - extraWidthAvailable; c < ncols ; c++, x -= widthOnComponent + hgap) { for (int r = 0, y = insets.top + extraHeightAvailable; r < nrows ; r++, y += heightOnComponent + vgap) { int i = r * ncols + c; if (i < ncomponents) { parent.getComponent(i).setBounds(x, y, widthOnComponent, heightOnComponent); } } } } } } /** * Returns the string representation of this grid layout's values. * @return a string representation of this grid layout */ public String toString() { return getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap + ",rows=" + rows + ",cols=" + cols + "]"; } }

Java example source code file (GridLayout.java) This example Java source code file (GridLayout.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM. Learn more about this Java project at its project page. Java - Java tags/keywords component, dimension, gridlayout, illegalargumentexception, insets, layoutmanager, string The GridLayout.java Java example source code /* * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt; /** * The <code>GridLayout class is a layout manager that * lays out a container's components in a rectangular grid. * The container is divided into equal-sized rectangles, * and one component is placed in each rectangle. * For example, the following is an applet that lays out six buttons * into three rows and two columns: * * <hr> * <pre> * import java.awt.*; * import java.applet.Applet; * public class ButtonGrid extends Applet { * public void init() { * setLayout(new GridLayout(3,2)); * add(new Button("1")); * add(new Button("2")); * add(new Button("3")); * add(new Button("4")); * add(new Button("5")); * add(new Button("6")); * } * } * </pre> * <p> * If the container's <code>ComponentOrientation property is horizontal * and left-to-right, the above example produces the output shown in Figure 1. * If the container's <code>ComponentOrientation property is horizontal * and right-to-left, the example produces the output shown in Figure 2. * * <table style="float:center" WIDTH=600 summary="layout"> * <tr ALIGN=CENTER> * <td> * * <td>Figure 2: Horizontal, Right-to-Left

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