tij0151.html

学习java的经典书籍

is produced using RTTI.
</FONT><a name="_Toc408018728"></a><P></DIV>
<A NAME="Heading465"></A><H3 ALIGN=LEFT>
Tool
tips
</H3>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Almost
all of the classes that you&#8217;ll be using to create your user interfaces
are derived from <A NAME="Index2284"></A><A NAME="Index2285"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JComponent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
which contains a method called <A NAME="Index2286"></A><A NAME="Index2287"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>setToolTipText(String)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.
So, for virtually anything you place on your form, all you need to do is say
(for an object 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>jc
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">of
any 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JComponent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">-derived
class):
</FONT><P></DIV><DIV ALIGN=LEFT><TT><FONT FACE="Courier New" SIZE=3 COLOR="Black">jc.setToolTipText("My
tip");
</FONT></TT><P></DIV><DIV ALIGN=LEFT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">and
when the mouse stays over that 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JComponent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
for a predetermined period of time, a tiny box containing your text will pop up
next to the mouse.
</FONT><a name="_Toc408018729"></a><P></DIV>
<A NAME="Heading466"></A><H3 ALIGN=LEFT>
Borders</H3>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JComponent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
also contains a method called <A NAME="Index2288"></A><A NAME="Index2289"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>setBorder(&#160;),</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
which allows you to place various interesting borders on any visible component.
The following example demonstrates a number of the different borders that are
available, using a method called 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>showBorder(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
that creates a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JPanel</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and puts on the border in each case. Also, it uses RTTI to find the name of the
border that you&#8217;re using (stripping off all the path information), then
puts that name in a <A NAME="Index2290"></A><A NAME="Index2291"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JLabel</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
in the middle of the panel:
</FONT><P></DIV>

<font color="#990000"><PRE><font color="#009900">//: Borders.java</font>
<font color="#009900">// Different Swing borders</font>
<font color="#0000ff">package</font> c13.swing;
<font color="#0000ff">import</font> java.awt.*;
<font color="#0000ff">import</font> java.awt.event.*;
<font color="#0000ff">import</font> com.sun.java.swing.*;
<font color="#0000ff">import</font> com.sun.java.swing.border.*;

<font color="#0000ff">public</font> <font color="#0000ff">class</font> Borders <font color="#0000ff">extends</font> JPanel {
  <font color="#0000ff">static</font> JPanel showBorder(Border b) {
    JPanel jp = <font color="#0000ff">new</font> JPanel();
    jp.setLayout(<font color="#0000ff">new</font> BorderLayout());
    String nm = b.getClass().toString();
    nm = nm.substring(nm.lastIndexOf('.') + 1);
    jp.add(<font color="#0000ff">new</font> JLabel(nm, JLabel.CENTER), 
      BorderLayout.CENTER);
    jp.setBorder(b);
    <font color="#0000ff">return</font> jp;
  }
  <font color="#0000ff">public</font> Borders() {
    setLayout(<font color="#0000ff">new</font> GridLayout(2,4));
    add(showBorder(<font color="#0000ff">new</font> TitledBorder("Title")));
    add(showBorder(<font color="#0000ff">new</font> EtchedBorder()));
    add(showBorder(<font color="#0000ff">new</font> LineBorder(Color.blue)));
    add(showBorder(
      <font color="#0000ff">new</font> MatteBorder(5,5,30,30,Color.green)));
    add(showBorder(
      <font color="#0000ff">new</font> BevelBorder(BevelBorder.RAISED)));
    add(showBorder(
      <font color="#0000ff">new</font> SoftBevelBorder(BevelBorder.LOWERED)));
    add(showBorder(<font color="#0000ff">new</font> CompoundBorder(
      <font color="#0000ff">new</font> EtchedBorder(),
      <font color="#0000ff">new</font> LineBorder(Color.red))));
  }
  <font color="#0000ff">public</font> <font color="#0000ff">static</font> <font color="#0000ff">void</font> main(String args[]) {
    Show.inFrame(<font color="#0000ff">new</font> Borders(), 500, 300);
  }
} <font color="#009900">///:~ </PRE></font></font><DIV ALIGN=LEFT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Most
of the examples in this section use <A NAME="Index2292"></A><A NAME="Index2293"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>TitledBorder</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
but you can see that the rest of the borders are as easy to use. You can also
create your own borders and put them inside buttons, labels, etc. &#8211;
anything derived from 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JComponent</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><a name="_Toc408018730"></a><P></DIV>
<A NAME="Heading467"></A><H3 ALIGN=LEFT>
Buttons</H3>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Swing
adds a number of different types of buttons, and it also changes the
organization of the selection components: all buttons, checkboxes, radio
buttons, and even menu items are inherited from <A NAME="Index2294"></A><A NAME="Index2295"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>AbstractButton</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
(which, since menu items are included, would probably have been better named
&#8220;AbstractChooser&#8221; or something equally general). You&#8217;ll see
the use of menu items shortly, but the following example shows the various
types of buttons available:
</FONT><P></DIV>

<font color="#990000"><PRE><font color="#009900">//: Buttons.java</font>
<font color="#009900">// Various Swing buttons</font>
<font color="#0000ff">package</font> c13.swing;
<font color="#0000ff">import</font> java.awt.*;
<font color="#0000ff">import</font> java.awt.event.*;
<font color="#0000ff">import</font> com.sun.java.swing.*;
<font color="#0000ff">import</font> com.sun.java.swing.basic.*;
<font color="#0000ff">import</font> com.sun.java.swing.border.*;

<font color="#0000ff">public</font> <font color="#0000ff">class</font> Buttons <font color="#0000ff">extends</font> JPanel {
  JButton jb = <font color="#0000ff">new</font> JButton("JButton");
  BasicArrowButton
    up = <font color="#0000ff">new</font> BasicArrowButton(
      BasicArrowButton.NORTH),
    down = <font color="#0000ff">new</font> BasicArrowButton(
      BasicArrowButton.SOUTH),
    right = <font color="#0000ff">new</font> BasicArrowButton(
      BasicArrowButton.EAST),
    left = <font color="#0000ff">new</font> BasicArrowButton(
      BasicArrowButton.WEST);
  Spinner spin = <font color="#0000ff">new</font> Spinner(47, "");
  StringSpinner stringSpin = 
    <font color="#0000ff">new</font> StringSpinner(3, "",
      <font color="#0000ff">new</font> String[] { 
        "red", "green", "blue", "yellow" });
  <font color="#0000ff">public</font> Buttons() {
    add(jb);
    add(<font color="#0000ff">new</font> JToggleButton("JToggleButton"));
    add(<font color="#0000ff">new</font> JCheckBox("JCheckBox"));
    add(<font color="#0000ff">new</font> JRadioButton("JRadioButton"));
    up.addActionListener(<font color="#0000ff">new</font> ActionListener() {
      <font color="#0000ff">public</font> <font color="#0000ff">void</font> actionPerformed(ActionEvent e){
        spin.setValue(spin.getValue() + 1);
      }
    });
    down.addActionListener(<font color="#0000ff">new</font> ActionListener() {
      <font color="#0000ff">public</font> <font color="#0000ff">void</font> actionPerformed(ActionEvent e){
        spin.setValue(spin.getValue() - 1);
      }
    });
    JPanel jp = <font color="#0000ff">new</font> JPanel();
    jp.add(spin);
    jp.add(up);
    jp.add(down);
    jp.setBorder(<font color="#0000ff">new</font> TitledBorder("Spinner"));
    add(jp);
    left.addActionListener(<font color="#0000ff">new</font> ActionListener() {
      <font color="#0000ff">public</font> <font color="#0000ff">void</font> actionPerformed(ActionEvent e){
        stringSpin.setValue(
          stringSpin.getValue() + 1);
      }
    });
    right.addActionListener(<font color="#0000ff">new</font> ActionListener(){
      <font color="#0000ff">public</font> <font color="#0000ff">void</font> actionPerformed(ActionEvent e){
        stringSpin.setValue(
          stringSpin.getValue() - 1);
      }
    });
    jp = <font color="#0000ff">new</font> JPanel();
    jp.add(stringSpin);
    jp.add(left);
    jp.add(right);
    jp.setBorder(
      <font color="#0000ff">new</font> TitledBorder("StringSpinner"));
    add(jp);
  }
  <font color="#0000ff">public</font> <font color="#0000ff">static</font> <font color="#0000ff">void</font> main(String args[]) {
    Show.inFrame(<font color="#0000ff">new</font> Buttons(), 300, 200);
  }
} <font color="#009900">///:~ </PRE></font></font><DIV ALIGN=LEFT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">The
<A NAME="Index2296"></A><A NAME="Index2297"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JButton</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
looks like the AWT button, but there&#8217;s more you can do to it (like add
images, as you&#8217;ll see later). In 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>com.sun.java.swing.basic</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
there is a <A NAME="Index2298"></A><A NAME="Index2299"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>BasicArrowButton</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
that is convenient, but what to test it on? There are two types of
&#8220;spinners&#8221; that just beg to be used with arrow buttons: <A NAME="Index2300"></A><A NAME="Index2301"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Spinner,</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
which changes an 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>int</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
value, and <A NAME="Index2302"></A><A NAME="Index2303"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>StringSpinner,</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
which moves through an array of 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>String</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
(even automatically wrapping when it reaches the end of the array). The 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>ActionListener</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">s
attached to the arrow buttons
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">shows
how relatively obvious it is to use these spinners: you just get and set
values, using method names you would expect since they&#8217;re Beans.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">When
you run the example, you&#8217;ll see that the toggle button holds its last
position, in or out. But the check boxes and radio buttons behave identically
to each other, just clicking on or off (they are inherited from <A NAME="Index2304"></A><A NAME="Index2305"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JToggleButton</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">).
</FONT><a name="_Toc408018731"></a><P></DIV>
<A NAME="Heading468"></A><H3 ALIGN=LEFT>
Button
groups
</H3>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">If
you want radio buttons to behave in an &#8220;exclusive or&#8221; fashion, you
must add them to a button group, in a similar but less awkward way as the old
AWT. But as the example below demonstrates, any 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>AbstractButton</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
can be added to a <A NAME="Index2306"></A><A NAME="Index2307"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>ButtonGroup</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">To
avoid repeating a lot of code, this example uses reflection to generate the
groups of different types of buttons. This is seen in 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>makeBPanel</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
which creates a button group and a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>JPanel</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,