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jsf、swing的官方指南

        <div id=PageTitle>Answers: Laying Out Components within a Container</div>
        <blockquote>
</blockquote>

<H3>Questions</H3>

<P>In each of the following questions, choose the layout manager(s)
most naturally suited for the described layout. Assume that the
container controlled by the layout manager is a <CODE>JPanel</CODE>.
[<I>Hint: </I>Two sections that might help are <A HREF="../components/components.html">A
Visual Index to Swing Components</A> and <A HREF="../layout/using.html#choosing">Tips
on Choosing a Layout Manager</A>.]</P>

<BLOCKQUOTE>
  <P><FONT COLOR="#ff0000">Question 1</FONT>. The container has
  one component that should take up as much space as possible<BR>
  <BLOCKQUOTE>
  <TABLE WIDTH="450" BORDER="0" CELLSPACING="2" CELLPADDING="0">
    <TR>
      <TD WIDTH="50%">
    <IMG SRC="../../figures/uiswing/QandE/Layout1-1.png" WIDTH="123" HEIGHT="60"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout1-1.png">
    </TD>
      <TD WIDTH="50%">
    <IMG SRC="../../figures/uiswing/QandE/Layout1-2.png" WIDTH="195" HEIGHT="100"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout1-2.png">
      </TD>
    </TR>
  </TABLE><p></P>

    <P>a. <CODE>BorderLayout</CODE><BR>
    b. <CODE>GridLayout</CODE><BR>
    c. <CODE>GridBagLayout</CODE><BR>
    d. a and b<BR>
    e. b and c</P>
  </BLOCKQUOTE>

  <P><FONT COLOR="#009900">Answer 1</FONT>: d. <code>BorderLayout</code> and <code>GridLayout</code> 
    easily deal with this situation. Although you could use <code>GridBagLayout</code>, 
    it's much more complex than necessary.</P>
  <BR>

  <P><FONT COLOR="#ff0000">Question 2</FONT>. The container has
  a row of components that should all be displayed at the same
  size, filling the container&#146;s entire area.</P>
    <BLOCKQUOTE>
    <IMG SRC="../../figures/uiswing/QandE/Layout2-1.png" WIDTH="348" HEIGHT="60"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout2-1.png">
    </BLOCKQUOTE>

    <BLOCKQUOTE>
    <IMG SRC="../../figures/uiswing/QandE/Layout2-2.png" WIDTH="395" HEIGHT="89"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout2-2.png">
    </BLOCKQUOTE>

  <BLOCKQUOTE>
    <P>a. <CODE>FlowLayout</CODE><BR>
    b. <CODE>GridLayout</CODE><BR>
    c. <CODE>BoxLayout</CODE><BR>
    d. a and b</P>
  </BLOCKQUOTE>

  <P><FONT COLOR="#009900">Answer 2</FONT>: b. This type of same-size layout &#151; 
    whether in a row, a column, or a grid &#151; is what <code>GridLayout</code> 
    is best at. </P>
  <BR>

  <P><FONT COLOR="#ff0000">Question 3</FONT>. The container displays
  a number of components in a column, with any extra space going
  between the first two components.<BR>
  <BLOCKQUOTE>
  <TABLE WIDTH="450" BORDER="0" CELLSPACING="2" CELLPADDING="0">
    <TR>
      <TD WIDTH="50%">
    <IMG SRC="../../figures/uiswing/QandE/Layout3-1.png" WIDTH="123" HEIGHT="138"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout3-1.png">
     </TD>
      <TD WIDTH="50%">
    <IMG SRC="../../figures/uiswing/QandE/Layout3-2.png" WIDTH="186" HEIGHT="180"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout3-2.png"> 
      </TD>
    </TR>
  </TABLE><p></P>
    <P>a. <CODE>FlowLayout</CODE><BR>
    b. <CODE>BoxLayout</CODE><BR>
    c. <CODE>GridLayout</CODE><BR>
    d. <CODE>BorderLayout</CODE></P>
  </BLOCKQUOTE>
  <P><FONT COLOR="#009900">Answer 3</FONT>: b. <code>BoxLayout</code> lays out 
    components in either a column or a row. You can specify extra space using 
    an invisible component.</P>
  <BR>

  <P><FONT COLOR="#ff0000">Question 4</FONT>. The container can
  display three completely different components at different times,
  depending perhaps on user input or program state. Even if the
  components&#146; sizes differ, switching from one component to
  the next shouldn&#146;t change the amount of space devoted to
  the component.</P>
    <BLOCKQUOTE>
    <IMG SRC="../../figures/uiswing/QandE/Layout4-1.png" WIDTH="347" HEIGHT="132"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout4-1.png">
    </BLOCKQUOTE>

    <BLOCKQUOTE>
    <p><IMG SRC="../../figures/uiswing/QandE/Layout4-2.png" WIDTH="347" HEIGHT="132"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout4-2.png"> </p>
      <P>a. <CODE>SpringLayout</CODE><BR>
      b. <CODE>BoxLayout</CODE><BR>
      c. <CODE>CardLayout</CODE><BR>
      d. <CODE>GridBagLayout</CODE></P>
    

  </BLOCKQUOTE>

  
<P><FONT COLOR="#009900">Answer 4</FONT>: c. <code>CardLayout</code> exists to 
  allow components to share the same space. Although it's simpler to use a <code>JTabbedPane</code> 
  component to control an area, <code>CardLayout</code> is the solution when you 
  don't want tabs.</P>
</BLOCKQUOTE>

<H3>Exercises</H3>

<BLOCKQUOTE>
  <P><FONT COLOR="#ff0000">Exercise 1</FONT>. Implement the layout
  described and shown in question 1.<BR>
    <FONT COLOR="#009900">Answer 1</FONT>: See <a target="source" href="examples/Layout1.java"><font color="#bb000f"><code>Layout1.java</code></font></a><a href="examples/Layout1.java"><img src="../../images/sourceIcon.gif" width=11 height=11 border=0 align="ABSMIDDLE" alt="(in a .java source file)"></a>. 
    Here's the code that implements the layout:</P>

	<blockquote><pre>JPanel p = new JPanel(new BorderLayout());
p.add(createComponent("Component 1"), 
                      BorderLayout.CENTER);
frame.setContentPane(p);</pre>
</blockquote>

  <br>
  <P><FONT COLOR="#ff0000">Exercise 2</FONT>. Implement the layout
  described and shown in question 2.<BR>
  <FONT COLOR="#009900">Answer 2</FONT>: See <a target="source" href="examples/Layout2.java"><font color="#bb000f"><code>Layout2.java</code></font></a><a href="examples/Layout2.java"><img src="../../images/sourceIcon.gif" width=11 height=11 border=0 align="ABSMIDDLE" alt="(in a .java source file)"></a>. 
    Here's the code that implements the layout:</P>

	<blockquote><pre>JPanel p = new JPanel(new GridLayout(1,0));
p.add(createComponent("Component 1"));
p.add(createComponent("Component 2"));
p.add(createComponent("Component 3"));
p.add(createComponent("Component 4"));
frame.setContentPane(p);
</pre>
</blockquote>

  <br>
  <P><FONT COLOR="#ff0000">Exercise 3</FONT>. Implement the layout
  described and shown in question 3.<BR>
  <FONT COLOR="#009900">Answer 3</FONT>: See <a target="source" href="examples/Layout3.java"><font color="#bb000f"><code>Layout3.java</code></font></a><a href="examples/Layout3.java"><img src="../../images/sourceIcon.gif" width=11 height=11 border=0 align="ABSMIDDLE" alt="(in a .java source file)"></a>. 
    Here's the code that implements the layout:</P>

	<blockquote><pre>JPanel p = new JPanel();
p.setLayout(new BoxLayout(p, BoxLayout.PAGE_AXIS));
p.add(createComponent("Component 1"));
p.add(Box.createVerticalGlue());
p.add(createComponent("Component 2"));
p.add(createComponent("Component 3"));
p.add(createComponent("Component 4"));
frame.setContentPane(p);
</pre>
</blockquote>


  <br>
  <P><FONT COLOR="#ff0000">Exercise 4</FONT>. Implement the layout
  described and shown in question 4.<BR>
  <FONT COLOR="#009900">Answer 4</FONT>: See <a target="source" href="examples/Layout4.java"><font color="#bb000f"><code>Layout4.java</code></font></a><a href="examples/Layout4.java"><img src="../../images/sourceIcon.gif" width=11 height=11 border=0 align="ABSMIDDLE" alt="(in a .java source file)"></a>. 
    Here's the code that implements the layout:</P>

	<blockquote><pre><em>...//Where the radio buttons are set up:</em>
for (int i= 0; i < strings.length; i++) {
    ...
	rb[i].setActionCommand(String.valueOf(i));
    ...
}

<em>...//Where the panel to contain the shared-space components is set up:</em>
cards = new JPanel(new CardLayout());
for (int i = 0; i < strings.length; i++) {
	cards.add(createComponent(strings[i]), String.valueOf(i));
}

<em>...//In the action listener for the radio buttons:</em>
public void actionPerformed(ActionEvent evt) {
	CardLayout cl = (CardLayout)(cards.getLayout());
	cl.show(cards, (String)evt.getActionCommand());
}</pre>
</blockquote>


  <br>
  <P><FONT COLOR="#ff0000">Exercise 5</FONT>. By adding a single line of code, 
    make the program you wrote for Exercise 2 display the components from right-to-left, 
    instead of from left-to-right.</P>
    <BLOCKQUOTE>
    <IMG SRC="../../figures/uiswing/QandE/Layout2-3.png" WIDTH="348" HEIGHT="60"
      ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Layout2-3.png">
    </BLOCKQUOTE>

  <P><FONT COLOR="#009900">Answer 5</FONT>: You can change the horizontal orientation 
    using the <code><a href="http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Component.html#setComponentOrientation(java.awt.ComponentOrientation)">setComponentOrientation</a></code> 
    method defined by the <code>Component</code> class. For example: 
  <blockquote><pre>p.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);</pre>
  </blockquote>
</BLOCKQUOTE>

        </blockquote>
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