AWT TextArea类

介绍

AWT TextArea控件提供给我们多行编辑区。用户可以在此处键入尽可能多他想要的。当文字在文本区域中成为大于可视区域，滚动条会自动出现，帮助我们滚动文本向上和向下，左与右。

类的声明

以下是声明为java.awt.TextArea类：

public class TextArea
   extends TextComponent

字段域

以是是类java.awt.TextArea字段：

static int SCROLLBARS_BOTH -- 创建和显示垂直和水平滚动条。
static int SCROLLBARS_HORIZONTAL_ONLY -- 创建和水平滚动条显示。
static int SCROLLBARS_NONE --不要建立或显示任何文本区域的滚动条。
static int SCROLLBARS_VERTICAL_ONLY -- 创建和垂直滚动条显示。

类的构造函数

S.N.	构造函数与说明
1	TextArea() Constructs a new text area with the empty string as text.
2	TextArea(int rows, int columns) Constructs a new text area with the specified number of rows and columns and the empty string as text.
3	TextArea(String text) Constructs a new text area with the specified text.
4	TextArea(String text, int rows, int columns) Constructs a new text area with the specified text, and with the specified number of rows and columns.
5	TextArea(String text, int rows, int columns, int scrollbars) Constructs a new text area with the specified text, and with the rows, columns, and scroll bar visibility as specified.

类方法

S.N.	方法& 描述
1	void addNotify() Creates the TextArea's peer.
2	void append(String str) Appends the given text to the text area's current text.
3	void appendText(String str) Deprecated. As of JDK version 1.1, replaced by append(String).
4	AccessibleContext getAccessibleContext() Returns the AccessibleContext associated with this TextArea.
5	int getColumns() Returns the number of columns in this text area.
6	Dimension getMinimumSize() Determines the minimum size of this text area.
7	Dimension getMinimumSize(int rows, int columns) Determines the minimum size of a text area with the specified number of rows and columns.
8	Dimension getPreferredSize() Determines the preferred size of this text area.
9	Dimension getPreferredSize(int rows, int columns) Determines the preferred size of a text area with the specified number of rows and columns.
10	int getRows() Returns the number of rows in the text area.
11	int getScrollbarVisibility() Returns an enumerated value that indicates which scroll bars the text area uses.
12	void insert(String str, int pos) Inserts the specified text at the specified position in this text area.
13	void insertText(String str, int pos) Deprecated. As of JDK version 1.1, replaced by insert(String, int).
14	Dimension minimumSize() Deprecated. As of JDK version 1.1, replaced by getMinimumSize().
15	Dimension minimumSize(int rows, int columns) Deprecated. As of JDK version 1.1, replaced by getMinimumSize(int, int).
16	protected String paramString() Returns a string representing the state of this TextArea.
17	Dimension preferredSize() Deprecated. As of JDK version 1.1, replaced by getPreferredSize().
18	Dimension preferredSize(int rows, int columns) Deprecated. As of JDK version 1.1, replaced by getPreferredSize(int, int).
19	void replaceRange(String str, int start, int end) Replaces text between the indicated start and end positions with the specified replacement text.
20	void replaceText(String str, int start, int end) Deprecated. As of JDK version 1.1, replaced by replaceRange(String, int, int).
21	void setColumns(int columns) Sets the number of columns for this text area.
22	void setRows(int rows) Sets the number of rows for this text area.

继承的方法

这个类从以下类继承的方法：

java.awt.TextComponent
java.awt.Component
java.lang.Object

TextArea 实例

选择使用任何编辑器创建以下java程序 D:/ > AWT > com > yiibai > gui >

AwtControlDemo

package com.yiibai.gui;

import java.awt.*;
import java.awt.event.*;

public class AwtControlDemo {

   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;

   public AwtControlDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      AwtControlDemo  awtControlDemo = new AwtControlDemo();
      awtControlDemo.showTextAreaDemo();
   }

   private void prepareGUI(){
      mainFrame = new Frame("Java AWT Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();        
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }

   private void showTextAreaDemo(){
      headerLabel.setText("Control in action: TextArea"); 

      Label  commentlabel= new Label("Comments: ", Label.RIGHT);

      final TextArea commentTextArea = new TextArea("This is a AWT tutorial "
      +"to make GUI application in Java.",5,30);

      Button showButton = new Button("Show");

      showButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {     
            statusLabel.setText( commentTextArea.getText());        
         }
      }); 

      controlPanel.add(commentlabel);
      controlPanel.add(commentTextArea);        
      controlPanel.add(showButton);
      mainFrame.setVisible(true);  
   }
}

编译程序，使用命令提示符。到 D:/ > AWT 然后键入以下命令。

D:AWT>javac comyiibaiguiAwtControlDemo.java

如果没有错误出现，这意味着编译成功。使用下面的命令来运行程序。

D:AWT>java com.yiibai.gui.AwtControlDemo

验证下面的输出