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The TextArea.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;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.awt.peer.TextAreaPeer;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
import javax.accessibility.*;
/**
* A <code>TextArea object is a multi-line region
* that displays text. It can be set to allow editing or
* to be read-only.
* <p>
* The following image shows the appearance of a text area:
* <p>
* <img src="doc-files/TextArea-1.gif" alt="A TextArea showing the word 'Hello!'"
* style="float:center; margin: 7px 10px;">
* <p>
* This text area could be created by the following line of code:
*
* <hr>
* new TextArea("Hello", 5, 40);
* </pre>
* <p>
* @author Sami Shaio
* @since JDK1.0
*/
public class TextArea extends TextComponent {
/**
* The number of rows in the <code>TextArea.
* This parameter will determine the text area's height.
* Guaranteed to be non-negative.
*
* @serial
* @see #getRows()
* @see #setRows(int)
*/
int rows;
/**
* The number of columns in the <code>TextArea.
* A column is an approximate average character
* width that is platform-dependent.
* This parameter will determine the text area's width.
* Guaranteed to be non-negative.
*
* @serial
* @see #setColumns(int)
* @see #getColumns()
*/
int columns;
private static final String base = "text";
private static int nameCounter = 0;
/**
* Create and display both vertical and horizontal scrollbars.
* @since JDK1.1
*/
public static final int SCROLLBARS_BOTH = 0;
/**
* Create and display vertical scrollbar only.
* @since JDK1.1
*/
public static final int SCROLLBARS_VERTICAL_ONLY = 1;
/**
* Create and display horizontal scrollbar only.
* @since JDK1.1
*/
public static final int SCROLLBARS_HORIZONTAL_ONLY = 2;
/**
* Do not create or display any scrollbars for the text area.
* @since JDK1.1
*/
public static final int SCROLLBARS_NONE = 3;
/**
* Determines which scrollbars are created for the
* text area. It can be one of four values :
* <code>SCROLLBARS_BOTH = both scrollbars.
* <code>SCROLLBARS_HORIZONTAL_ONLY = Horizontal bar only.
* <code>SCROLLBARS_VERTICAL_ONLY = Vertical bar only.
* <code>SCROLLBARS_NONE = No scrollbars.
*
* @serial
* @see #getScrollbarVisibility()
*/
private int scrollbarVisibility;
/**
* Cache the Sets of forward and backward traversal keys so we need not
* look them up each time.
*/
private static Set<AWTKeyStroke> forwardTraversalKeys, backwardTraversalKeys;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = 3692302836626095722L;
/**
* Initialize JNI field and method ids
*/
private static native void initIDs();
static {
/* ensure that the necessary native libraries are loaded */
Toolkit.loadLibraries();
if (!GraphicsEnvironment.isHeadless()) {
initIDs();
}
forwardTraversalKeys = KeyboardFocusManager.initFocusTraversalKeysSet(
"ctrl TAB",
new HashSet<AWTKeyStroke>());
backwardTraversalKeys = KeyboardFocusManager.initFocusTraversalKeysSet(
"ctrl shift TAB",
new HashSet<AWTKeyStroke>());
}
/**
* Constructs a new text area with the empty string as text.
* This text area is created with scrollbar visibility equal to
* {@link #SCROLLBARS_BOTH}, so both vertical and horizontal
* scrollbars will be visible for this text area.
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless returns true
* @see java.awt.GraphicsEnvironment#isHeadless()
*/
public TextArea() throws HeadlessException {
this("", 0, 0, SCROLLBARS_BOTH);
}
/**
* Constructs a new text area with the specified text.
* This text area is created with scrollbar visibility equal to
* {@link #SCROLLBARS_BOTH}, so both vertical and horizontal
* scrollbars will be visible for this text area.
* @param text the text to be displayed; if
* <code>text is null, the empty
* string <code>"" will be displayed
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless returns true
* @see java.awt.GraphicsEnvironment#isHeadless()
*/
public TextArea(String text) throws HeadlessException {
this(text, 0, 0, SCROLLBARS_BOTH);
}
/**
* Constructs a new text area with the specified number of
* rows and columns and the empty string as text.
* A column is an approximate average character
* width that is platform-dependent. The text area is created with
* scrollbar visibility equal to {@link #SCROLLBARS_BOTH}, so both
* vertical and horizontal scrollbars will be visible for this
* text area.
* @param rows the number of rows
* @param columns the number of columns
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless returns true
* @see java.awt.GraphicsEnvironment#isHeadless()
*/
public TextArea(int rows, int columns) throws HeadlessException {
this("", rows, columns, SCROLLBARS_BOTH);
}
/**
* Constructs a new text area with the specified text,
* and with the specified number of rows and columns.
* A column is an approximate average character
* width that is platform-dependent. The text area is created with
* scrollbar visibility equal to {@link #SCROLLBARS_BOTH}, so both
* vertical and horizontal scrollbars will be visible for this
* text area.
* @param text the text to be displayed; if
* <code>text is null, the empty
* string <code>"" will be displayed
* @param rows the number of rows
* @param columns the number of columns
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless returns true
* @see java.awt.GraphicsEnvironment#isHeadless()
*/
public TextArea(String text, int rows, int columns)
throws HeadlessException {
this(text, rows, columns, SCROLLBARS_BOTH);
}
/**
* Constructs a new text area with the specified text,
* and with the rows, columns, and scroll bar visibility
* as specified. All <code>TextArea constructors defer to
* this one.
* <p>
* The <code>TextArea class defines several constants
* that can be supplied as values for the
* <code>scrollbars argument:
* <ul>
* <li>SCROLLBARS_BOTH,
* <li>SCROLLBARS_VERTICAL_ONLY,
* <li>SCROLLBARS_HORIZONTAL_ONLY,
* <li>SCROLLBARS_NONE.
* </ul>
* Any other value for the
* <code>scrollbars argument is invalid and will result in
* this text area being created with scrollbar visibility equal to
* the default value of {@link #SCROLLBARS_BOTH}.
* @param text the text to be displayed; if
* <code>text is null, the empty
* string <code>"" will be displayed
* @param rows the number of rows; if
* <code>rows is less than 0,
* <code>rows is set to 0
* @param columns the number of columns; if
* <code>columns is less than 0,
* <code>columns is set to 0
* @param scrollbars a constant that determines what
* scrollbars are created to view the text area
* @since JDK1.1
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless returns true
* @see java.awt.GraphicsEnvironment#isHeadless()
*/
public TextArea(String text, int rows, int columns, int scrollbars)
throws HeadlessException {
super(text);
this.rows = (rows >= 0) ? rows : 0;
this.columns = (columns >= 0) ? columns : 0;
if (scrollbars >= SCROLLBARS_BOTH && scrollbars <= SCROLLBARS_NONE) {
this.scrollbarVisibility = scrollbars;
} else {
this.scrollbarVisibility = SCROLLBARS_BOTH;
}
setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
forwardTraversalKeys);
setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS,
backwardTraversalKeys);
}
/**
* Construct a name for this component. Called by <code>getName
* when the name is <code>null.
*/
String constructComponentName() {
synchronized (TextArea.class) {
return base + nameCounter++;
}
}
/**
* Creates the <code>TextArea's peer. The peer allows us to modify
* the appearance of the <code>TextArea without changing any of its
* functionality.
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = getToolkit().createTextArea(this);
super.addNotify();
}
}
/**
* Inserts the specified text at the specified position
* in this text area.
* <p>Note that passing null or inconsistent
* parameters is invalid and will result in unspecified
* behavior.
*
* @param str the non-<code>null text to insert
* @param pos the position at which to insert
* @see java.awt.TextComponent#setText
* @see java.awt.TextArea#replaceRange
* @see java.awt.TextArea#append
* @since JDK1.1
*/
public void insert(String str, int pos) {
insertText(str, pos);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>insert(String, int).
*/
@Deprecated
public synchronized void insertText(String str, int pos) {
TextAreaPeer peer = (TextAreaPeer)this.peer;
if (peer != null) {
peer.insert(str, pos);
} else {
text = text.substring(0, pos) + str + text.substring(pos);
}
}
/**
* Appends the given text to the text area's current text.
* <p>Note that passing null or inconsistent
* parameters is invalid and will result in unspecified
* behavior.
*
* @param str the non-<code>null text to append
* @see java.awt.TextArea#insert
* @since JDK1.1
*/
public void append(String str) {
appendText(str);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>append(String).
*/
@Deprecated
public synchronized void appendText(String str) {
if (peer != null) {
insertText(str, getText().length());
} else {
text = text + str;
}
}
/**
* Replaces text between the indicated start and end positions
* with the specified replacement text. The text at the end
* position will not be replaced. The text at the start
* position will be replaced (unless the start position is the
* same as the end position).
* The text position is zero-based. The inserted substring may be
* of a different length than the text it replaces.
* <p>Note that passing null or inconsistent
* parameters is invalid and will result in unspecified
* behavior.
*
* @param str the non-<code>null text to use as
* the replacement
* @param start the start position
* @param end the end position
* @see java.awt.TextArea#insert
* @since JDK1.1
*/
public void replaceRange(String str, int start, int end) {
replaceText(str, start, end);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>replaceRange(String, int, int).
*/
@Deprecated
public synchronized void replaceText(String str, int start, int end) {
TextAreaPeer peer = (TextAreaPeer)this.peer;
if (peer != null) {
peer.replaceRange(str, start, end);
} else {
text = text.substring(0, start) + str + text.substring(end);
}
}
/**
* Returns the number of rows in the text area.
* @return the number of rows in the text area
* @see #setRows(int)
* @see #getColumns()
* @since JDK1
*/
public int getRows() {
return rows;
}
/**
* Sets the number of rows for this text area.
* @param rows the number of rows
* @see #getRows()
* @see #setColumns(int)
* @exception IllegalArgumentException if the value
* supplied for <code>rows
* is less than <code>0
* @since JDK1.1
*/
public void setRows(int rows) {
int oldVal = this.rows;
if (rows < 0) {
throw new IllegalArgumentException("rows less than zero.");
}
if (rows != oldVal) {
this.rows = rows;
invalidate();
}
}
/**
* Returns the number of columns in this text area.
* @return the number of columns in the text area
* @see #setColumns(int)
* @see #getRows()
*/
public int getColumns() {
return columns;
}
/**
* Sets the number of columns for this text area.
* @param columns the number of columns
* @see #getColumns()
* @see #setRows(int)
* @exception IllegalArgumentException if the value
* supplied for <code>columns
* is less than <code>0
* @since JDK1.1
*/
public void setColumns(int columns) {
int oldVal = this.columns;
if (columns < 0) {
throw new IllegalArgumentException("columns less than zero.");
}
if (columns != oldVal) {
this.columns = columns;
invalidate();
}
}
/**
* Returns an enumerated value that indicates which scroll bars
* the text area uses.
* <p>
* The <code>TextArea class defines four integer constants
* that are used to specify which scroll bars are available.
* <code>TextArea has one constructor that gives the
* application discretion over scroll bars.
*
* @return an integer that indicates which scroll bars are used
* @see java.awt.TextArea#SCROLLBARS_BOTH
* @see java.awt.TextArea#SCROLLBARS_VERTICAL_ONLY
* @see java.awt.TextArea#SCROLLBARS_HORIZONTAL_ONLY
* @see java.awt.TextArea#SCROLLBARS_NONE
* @see java.awt.TextArea#TextArea(java.lang.String, int, int, int)
* @since JDK1.1
*/
public int getScrollbarVisibility() {
return scrollbarVisibility;
}
/**
* Determines the preferred size of a text area with the specified
* number of rows and columns.
* @param rows the number of rows
* @param columns the number of columns
* @return the preferred dimensions required to display
* the text area with the specified
* number of rows and columns
* @see java.awt.Component#getPreferredSize
* @since JDK1.1
*/
public Dimension getPreferredSize(int rows, int columns) {
return preferredSize(rows, columns);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getPreferredSize(int, int).
*/
@Deprecated
public Dimension preferredSize(int rows, int columns) {
synchronized (getTreeLock()) {
TextAreaPeer peer = (TextAreaPeer)this.peer;
return (peer != null) ?
peer.getPreferredSize(rows, columns) :
super.preferredSize();
}
}
/**
* Determines the preferred size of this text area.
* @return the preferred dimensions needed for this text area
* @see java.awt.Component#getPreferredSize
* @since JDK1.1
*/
public Dimension getPreferredSize() {
return preferredSize();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getPreferredSize().
*/
@Deprecated
public Dimension preferredSize() {
synchronized (getTreeLock()) {
return ((rows > 0) && (columns > 0)) ?
preferredSize(rows, columns) :
super.preferredSize();
}
}
/**
* Determines the minimum size of a text area with the specified
* number of rows and columns.
* @param rows the number of rows
* @param columns the number of columns
* @return the minimum dimensions required to display
* the text area with the specified
* number of rows and columns
* @see java.awt.Component#getMinimumSize
* @since JDK1.1
*/
public Dimension getMinimumSize(int rows, int columns) {
return minimumSize(rows, columns);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getMinimumSize(int, int).
*/
@Deprecated
public Dimension minimumSize(int rows, int columns) {
synchronized (getTreeLock()) {
TextAreaPeer peer = (TextAreaPeer)this.peer;
return (peer != null) ?
peer.getMinimumSize(rows, columns) :
super.minimumSize();
}
}
/**
* Determines the minimum size of this text area.
* @return the preferred dimensions needed for this text area
* @see java.awt.Component#getPreferredSize
* @since JDK1.1
*/
public Dimension getMinimumSize() {
return minimumSize();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by <code>getMinimumSize().
*/
@Deprecated
public Dimension minimumSize() {
synchronized (getTreeLock()) {
return ((rows > 0) && (columns > 0)) ?
minimumSize(rows, columns) :
super.minimumSize();
}
}
/**
* Returns a string representing the state of this <code>TextArea.
* 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 text area
*/
protected String paramString() {
String sbVisStr;
switch (scrollbarVisibility) {
case SCROLLBARS_BOTH:
sbVisStr = "both";
break;
case SCROLLBARS_VERTICAL_ONLY:
sbVisStr = "vertical-only";
break;
case SCROLLBARS_HORIZONTAL_ONLY:
sbVisStr = "horizontal-only";
break;
case SCROLLBARS_NONE:
sbVisStr = "none";
break;
default:
sbVisStr = "invalid display policy";
}
return super.paramString() + ",rows=" + rows +
",columns=" + columns +
",scrollbarVisibility=" + sbVisStr;
}
/*
* Serialization support.
*/
/**
* The textArea Serialized Data Version.
*
* @serial
*/
private int textAreaSerializedDataVersion = 2;
/**
* Read the ObjectInputStream.
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless() returns
* <code>true
* @see java.awt.GraphicsEnvironment#isHeadless
*/
private void readObject(ObjectInputStream s)
throws ClassNotFoundException, IOException, HeadlessException
{
// HeadlessException will be thrown by TextComponent's readObject
s.defaultReadObject();
// Make sure the state we just read in for columns, rows,
// and scrollbarVisibility has legal values
if (columns < 0) {
columns = 0;
}
if (rows < 0) {
rows = 0;
}
if ((scrollbarVisibility < SCROLLBARS_BOTH) ||
(scrollbarVisibility > SCROLLBARS_NONE)) {
this.scrollbarVisibility = SCROLLBARS_BOTH;
}
if (textAreaSerializedDataVersion < 2) {
setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
forwardTraversalKeys);
setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS,
backwardTraversalKeys);
}
}
/////////////////
// Accessibility support
////////////////
/**
* Returns the <code>AccessibleContext associated with
* this <code>TextArea. For text areas, the
* <code>AccessibleContext takes the form of an
* <code>AccessibleAWTTextArea.
* A new <code>AccessibleAWTTextArea instance is created if necessary.
*
* @return an <code>AccessibleAWTTextArea that serves as the
* <code>AccessibleContext of this TextArea
* @since 1.3
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleAWTTextArea();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* <code>TextArea class. It provides an implementation of the
* Java Accessibility API appropriate to text area user-interface elements.
* @since 1.3
*/
protected class AccessibleAWTTextArea extends AccessibleAWTTextComponent
{
/*
* JDK 1.3 serialVersionUID
*/
private static final long serialVersionUID = 3472827823632144419L;
/**
* Gets the state set of this object.
*
* @return an instance of AccessibleStateSet describing the states
* of the object
* @see AccessibleStateSet
*/
public AccessibleStateSet getAccessibleStateSet() {
AccessibleStateSet states = super.getAccessibleStateSet();
states.add(AccessibleState.MULTI_LINE);
return states;
}
}
}
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