| /* | |
| * Copyright (c) 1995, 2021, 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; | |
| import java.awt.peer.LabelPeer; | |
| import java.io.IOException; | |
| import java.io.ObjectInputStream; | |
| import java.io.Serial; | |
| import javax.accessibility.Accessible; | |
| import javax.accessibility.AccessibleContext; | |
| import javax.accessibility.AccessibleRole; | |
| /** | |
| * A {@code Label} object is a component for placing text in a | |
| * container. A label displays a single line of read-only text. | |
| * The text can be changed by the application, but a user cannot edit it | |
| * directly. | |
| * <p> | |
| * For example, the code . . . | |
| * | |
| * <hr><blockquote><pre> | |
| * setLayout(new FlowLayout(FlowLayout.CENTER, 10, 10)); | |
| * add(new Label("Hi There!")); | |
| * add(new Label("Another Label")); | |
| * </pre></blockquote><hr> | |
| * <p> | |
| * produces the following labels: | |
| * <p> | |
| * <img src="doc-files/Label-1.gif" alt="Two labels: 'Hi There!' and | |
| * 'Another label'" style="margin: 7px 10px;"> | |
| * | |
| * @author Sami Shaio | |
| * @since 1.0 | |
| */ | |
| public class Label extends Component implements Accessible { | |
| static { | |
| /* ensure that the necessary native libraries are loaded */ | |
| Toolkit.loadLibraries(); | |
| if (!GraphicsEnvironment.isHeadless()) { | |
| initIDs(); | |
| } | |
| } | |
| /** | |
| * Indicates that the label should be left justified. | |
| */ | |
| public static final int LEFT = 0; | |
| /** | |
| * Indicates that the label should be centered. | |
| */ | |
| public static final int CENTER = 1; | |
| /** | |
| * Indicates that the label should be right justified. | |
| */ | |
| public static final int RIGHT = 2; | |
| /** | |
| * The text of this label. | |
| * This text can be modified by the program | |
| * but never by the user. | |
| * | |
| * @serial | |
| * @see #getText() | |
| * @see #setText(String) | |
| */ | |
| String text; | |
| /** | |
| * The label's alignment. The default alignment is set | |
| * to be left justified. | |
| * | |
| * @serial | |
| * @see #getAlignment() | |
| * @see #setAlignment(int) | |
| */ | |
| int alignment = LEFT; | |
| private static final String base = "label"; | |
| private static int nameCounter = 0; | |
| /** | |
| * Use serialVersionUID from JDK 1.1 for interoperability. | |
| */ | |
| @Serial | |
| private static final long serialVersionUID = 3094126758329070636L; | |
| /** | |
| * Constructs an empty label. | |
| * The text of the label is the empty string {@code ""}. | |
| * @throws HeadlessException if GraphicsEnvironment.isHeadless() | |
| * returns true. | |
| * @see java.awt.GraphicsEnvironment#isHeadless | |
| */ | |
| public Label() throws HeadlessException { | |
| this("", LEFT); | |
| } | |
| /** | |
| * Constructs a new label with the specified string of text, | |
| * left justified. | |
| * @param text the string that the label presents. | |
| * A {@code null} value | |
| * will be accepted without causing a NullPointerException | |
| * to be thrown. | |
| * @throws HeadlessException if GraphicsEnvironment.isHeadless() | |
| * returns true. | |
| * @see java.awt.GraphicsEnvironment#isHeadless | |
| */ | |
| public Label(String text) throws HeadlessException { | |
| this(text, LEFT); | |
| } | |
| /** | |
| * Constructs a new label that presents the specified string of | |
| * text with the specified alignment. | |
| * Possible values for {@code alignment} are {@code Label.LEFT}, | |
| * {@code Label.RIGHT}, and {@code Label.CENTER}. | |
| * @param text the string that the label presents. | |
| * A {@code null} value | |
| * will be accepted without causing a NullPointerException | |
| * to be thrown. | |
| * @param alignment the alignment value. | |
| * @throws HeadlessException if GraphicsEnvironment.isHeadless() | |
| * returns true. | |
| * @see java.awt.GraphicsEnvironment#isHeadless | |
| */ | |
| public Label(String text, int alignment) throws HeadlessException { | |
| GraphicsEnvironment.checkHeadless(); | |
| this.text = text; | |
| setAlignment(alignment); | |
| } | |
| /** | |
| * Read a label from an object input stream. | |
| * | |
| * @param s the {@code ObjectInputStream} to read | |
| * @throws ClassNotFoundException if the class of a serialized object could | |
| * not be found | |
| * @throws IOException if an I/O error occurs | |
| * @throws HeadlessException if {@code GraphicsEnvironment.isHeadless()} | |
| * returns {@code true} | |
| * | |
| * @see java.awt.GraphicsEnvironment#isHeadless | |
| * @since 1.4 | |
| */ | |
| @Serial | |
| private void readObject(ObjectInputStream s) | |
| throws ClassNotFoundException, IOException, HeadlessException { | |
| GraphicsEnvironment.checkHeadless(); | |
| s.defaultReadObject(); | |
| } | |
| /** | |
| * Construct a name for this component. Called by getName() when the | |
| * name is {@code null}. | |
| */ | |
| String constructComponentName() { | |
| synchronized (Label.class) { | |
| return base + nameCounter++; | |
| } | |
| } | |
| /** | |
| * Creates the peer for this label. The peer allows us to | |
| * modify the appearance of the label without changing its | |
| * functionality. | |
| */ | |
| public void addNotify() { | |
| synchronized (getTreeLock()) { | |
| if (peer == null) | |
| peer = getComponentFactory().createLabel(this); | |
| super.addNotify(); | |
| } | |
| } | |
| /** | |
| * Gets the current alignment of this label. Possible values are | |
| * {@code Label.LEFT}, {@code Label.RIGHT}, and | |
| * {@code Label.CENTER}. | |
| * @return the alignment of this label | |
| * @see java.awt.Label#setAlignment | |
| */ | |
| public int getAlignment() { | |
| return alignment; | |
| } | |
| /** | |
| * Sets the alignment for this label to the specified alignment. | |
| * Possible values are {@code Label.LEFT}, | |
| * {@code Label.RIGHT}, and {@code Label.CENTER}. | |
| * @param alignment the alignment to be set. | |
| * @throws IllegalArgumentException if an improper value for | |
| * {@code alignment} is given. | |
| * @see java.awt.Label#getAlignment | |
| */ | |
| public synchronized void setAlignment(int alignment) { | |
| switch (alignment) { | |
| case LEFT: | |
| case CENTER: | |
| case RIGHT: | |
| this.alignment = alignment; | |
| LabelPeer peer = (LabelPeer)this.peer; | |
| if (peer != null) { | |
| peer.setAlignment(alignment); | |
| } | |
| return; | |
| } | |
| throw new IllegalArgumentException("improper alignment: " + alignment); | |
| } | |
| /** | |
| * Gets the text of this label. | |
| * @return the text of this label, or {@code null} if | |
| * the text has been set to {@code null}. | |
| * @see java.awt.Label#setText | |
| */ | |
| public String getText() { | |
| return text; | |
| } | |
| /** | |
| * Sets the text for this label to the specified text. | |
| * @param text the text that this label displays. If | |
| * {@code text} is {@code null}, it is | |
| * treated for display purposes like an empty | |
| * string {@code ""}. | |
| * @see java.awt.Label#getText | |
| */ | |
| public void setText(String text) { | |
| boolean testvalid = false; | |
| synchronized (this) { | |
| if (text != this.text && (this.text == null || | |
| !this.text.equals(text))) { | |
| this.text = text; | |
| LabelPeer peer = (LabelPeer)this.peer; | |
| if (peer != null) { | |
| peer.setText(text); | |
| } | |
| testvalid = true; | |
| } | |
| } | |
| // This could change the preferred size of the Component. | |
| if (testvalid) { | |
| invalidateIfValid(); | |
| } | |
| } | |
| /** | |
| * Returns a string representing the state of this {@code Label}. | |
| * This method is intended to be used only for debugging purposes, and the | |
| * content and format of the returned string may vary between | |
| * implementations. The returned string may be empty but may not be | |
| * {@code null}. | |
| * | |
| * @return the parameter string of this label | |
| */ | |
| protected String paramString() { | |
| String align = ""; | |
| switch (alignment) { | |
| case LEFT: align = "left"; break; | |
| case CENTER: align = "center"; break; | |
| case RIGHT: align = "right"; break; | |
| } | |
| return super.paramString() + ",align=" + align + ",text=" + text; | |
| } | |
| /** | |
| * Initialize JNI field and method IDs | |
| */ | |
| private static native void initIDs(); | |
| ///////////////// | |
| // Accessibility support | |
| //////////////// | |
| /** | |
| * Gets the AccessibleContext associated with this Label. | |
| * For labels, the AccessibleContext takes the form of an | |
| * AccessibleAWTLabel. | |
| * A new AccessibleAWTLabel instance is created if necessary. | |
| * | |
| * @return an AccessibleAWTLabel that serves as the | |
| * AccessibleContext of this Label | |
| * @since 1.3 | |
| */ | |
| public AccessibleContext getAccessibleContext() { | |
| if (accessibleContext == null) { | |
| accessibleContext = new AccessibleAWTLabel(); | |
| } | |
| return accessibleContext; | |
| } | |
| /** | |
| * This class implements accessibility support for the | |
| * {@code Label} class. It provides an implementation of the | |
| * Java Accessibility API appropriate to label user-interface elements. | |
| * @since 1.3 | |
| */ | |
| protected class AccessibleAWTLabel extends AccessibleAWTComponent | |
| { | |
| /** | |
| * Use serialVersionUID from JDK 1.3 for interoperability. | |
| */ | |
| @Serial | |
| private static final long serialVersionUID = -3568967560160480438L; | |
| /** | |
| * Constructor for the accessible label. | |
| */ | |
| public AccessibleAWTLabel() { | |
| super(); | |
| } | |
| /** | |
| * Get the accessible name of this object. | |
| * | |
| * @return the localized name of the object -- can be null if this | |
| * object does not have a name | |
| * @see AccessibleContext#setAccessibleName | |
| */ | |
| public String getAccessibleName() { | |
| if (accessibleName != null) { | |
| return accessibleName; | |
| } else { | |
| if (getText() == null) { | |
| return super.getAccessibleName(); | |
| } else { | |
| return getText(); | |
| } | |
| } | |
| } | |
| /** | |
| * Get the role of this object. | |
| * | |
| * @return an instance of AccessibleRole describing the role of the object | |
| * @see AccessibleRole | |
| */ | |
| public AccessibleRole getAccessibleRole() { | |
| return AccessibleRole.LABEL; | |
| } | |
| } // inner class AccessibleAWTLabel | |
| } |