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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"><html> <head> <title>Solving Common Layout Problems (The Java™ Tutorials > Creating a GUI with JFC/Swing > Laying Out Components Within a Container)</title><style type="text/css"> .FigureCaption { margin-left: 1in; margin-right: 1in; font-family: sans-serif; font-size: smaller; text-align: justify; } #TopBar_bl { background: url(../../images/java_bar_bl.gif) 0 100% no-repeat; width: 100%; height: 60px; } #TopBar_br { background: url(../../images/java_bar_br.gif) 100% 100% no-repeat; width: 100%; height: 60px; } #TopBar_tl { background: url(../../images/java_bar_tl.gif) 0 0 no-repeat; width: 100%; height: 60px; } #TopBar_tr { background: url(../../images/java_bar_tr.gif) 100% 0 no-repeat; width: 100%; height: 60px; } #TopBar { background: #35556B url(../../images/java_bar.gif); margin: 10px 10px 0 10px; height:60px; min-width:700px; color: white; font-family: sans-serif; font-weight: bold; } @media print { #BreadCrumbs, #Download { display: none; 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var main = document.getElementById("MainFlow"); var toggle = document.getElementById("ToggleLeft"); if (b) { contents.className = "LeftBar_shown"; main.className = "MainFlow_indented"; toggle.innerHTML = "Hide the TOC"; document.cookie = 'tutorial_showLeftBar=yes; path=/'; } else { contents.className = "LeftBar_hidden"; main.className = "MainFlow_wide"; toggle.innerHTML = "Show the TOC"; document.cookie = 'tutorial_showLeftBar=no; path=/'; } } function toggleLeft() { showLeft(document.getElementById("LeftBar").className == "LeftBar_hidden"); document.getElementById("ToggleLeft").blur(); } function load() { showLeft(leftBar()); document.getElementById("ToggleLeft").style.display="inline"; } </script> </head><body onload="load()"> <div id=TopBar> <div id=TopBar_tr> <div id=TopBar_tl> <div id=TopBar_br> <div id=TopBar_bl> <div id=TopBar_right> <a target="_blank" href="http://java.sun.com/javase/6/download.jsp">Download the JDK</a> <br> <a href="../../search.html" target="_blank">Search the Tutorials</a> <br> <a href="javascript:toggleLeft()" id="ToggleLeft">Hide the TOC</a> </div> </div> </div> </div> </div> </div> <div class=PrintHeaders> <b>Trail:</b> Creating a GUI with JFC/Swing <br><b>Lesson:</b> Laying Out Components Within a Container </div> <div id=LeftBar class=LeftBar_shown> <div id=Contents> <div class="linkLESSON"><a href="index.html">Laying Out Components Within a Container</a></div><div class="linkAHEAD"><a href="visual.html">A Visual Guide to Layout Managers</a></div><div class="linkAHEAD"><a href="using.html">Using Layout Managers</a></div><div class="linkAHEAD"><a href="howLayoutWorks.html">How Layout Management Works</a></div><div class="linkAHEAD"><a href="layoutlist.html">How to Use Various Layout Managers</a></div><div class="linkAHEAD"><a href="border.html">How to Use BorderLayout</a></div><div class="linkAHEAD"><a href="box.html">How to Use BoxLayout</a></div><div class="linkAHEAD"><a href="card.html">How to Use CardLayout</a></div><div class="linkAHEAD"><a href="flow.html">How to Use FlowLayout</a></div><div class="linkAHEAD"><a href="gridbag.html">How to Use GridBagLayout</a></div><div class="linkAHEAD"><a href="grid.html">How to Use GridLayout</a></div><div class="linkAHEAD"><a href="group.html">How to Use GroupLayout</a></div><div class="linkBHEAD"><a href="groupExample.html">A GroupLayout Example</a></div><div class="linkAHEAD"><a href="spring.html">How to Use SpringLayout</a></div><div class="linkAHEAD"><a href="custom.html">Creating a Custom Layout Manager</a></div><div class="linkAHEAD"><a href="none.html">Doing Without a Layout Manager (Absolute Positioning)</a></div><div class="nolinkAHEAD">Solving Common Layout Problems</div></div> </div> <div id=MainFlow class=MainFlow_indented> <span id=BreadCrumbs> <a href=../../index.html target=_top>Home Page</a> > <a href=../index.html target=_top>Creating a GUI with JFC/Swing</a> > <a href=index.html target=_top>Laying Out Components Within a Container</a> </span> <div class=NavBit> <a target=_top href=none.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=../QandE/questions-ch4.html>Next »</a> </div> <div id=PageTitle>Solving Common Layout Problems</div> <blockquote><strong>Problem:</strong>How do I specify a component's exact size?<ul><li>First, make sure that you really need to set the component's exact size. Each Swing component has a different preferred size, depending on the font it uses and the look and feel. For this reason, it often doesn't make sense to specify a Swing component's exact size. <p><li>If the component isn't controlled by a layout manager, you can set its size by invoking the <code>setSize</code> or <code>setBounds</code> method on it. Otherwise, you need to provide size hints and then make sure you're using a layout manager that respects the size hints. <p><li>If you extend a Swing component class, you can give size hints by overriding the component's <code>getMinimumSize</code>, <code>getPreferredSize</code>, and <code>getMaximumSize</code> methods. What's nice about this approach is that each <code>get<em>Xxxx</em>Size</code> method can get the component's default size hints by invoking <code>super.get<em>Xxxx</em>Size()</code>. Then it can adjust the size, if necessary, before returning it. <p><li>Another way to give size hints is to invoke the component's <code>setMinimumSize</code>, <code>setPreferredSize</code>, and <code>setMaximumSize</code> methods.</ul><blockquote><hr><strong>Note:</strong> No matter how you specify your component's size,be sure that your component's container usesa layout manager that respects the requested size of the component.The <code>FlowLayout</code> and <code>GridBagLayout</code> managersuse the component's preferred size(the latter depending on the constraintsthat you set),but <code>BorderLayout</code> and <code>GridLayout</code> usually don't.The <code>BoxLayout</code> manager generallyuses a component's preferred size(although components can be larger),and is one of the few layout managers that respectsthe component's maximum size.<p>If you specify new size hints for a component that's already visible,you then need to invoke the <code>revalidate</code> method on it,to make sure that its containment hierarchy is laid out again.Then invoke the <code>repaint</code> method.<hr></blockquote><p><strong>Problem:</strong>My custom component is being sized too small.<ul><li>Does the component implement the <code>getPreferredSize</code> and <code>getMinimumSize</code> methods? If so, do they return the right values?<li>Are you using a layout manager that can use as much space as is available? See <a href=using.html#choosing>Tips on Choosing a Layout Manager</a> for some tips on choosing a layout manager and specifying that it use the maximum available space for a particular component.</ul><p>If you don't see your problem in this list, see<a class="TutorialLink" target="_top" href="../components/problems.html">Solving Common Component Problems</a>. </blockquote> <div class=NavBit> <a target=_top href=none.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=../QandE/questions-ch4.html>Next »</a> </div> </div> <div id=Footer><div id=TagNotes> Problems with the examples? Try <a target="_blank" href=../../information/run-examples.html>Compiling and Running the Examples: FAQs</a>. <br> Complaints? Compliments? Suggestions? <a target="_blank" href="http://developer.sun.com/contact/tutorial_feedback.jsp">Give us your feedback</a>.<br><br> <a target="_blank" href="../../information/copyright.html">Copyright</a> 1995-2006 Sun Microsystems, Inc. All rights reserved. <span id=Download></span></div> </div> <div class=PrintHeaders> <b>Previous page:</b> Doing Without a Layout Manager (Absolute Positioning) <br><b>Next page:</b> Questions and Exercises: Laying Out Components within a Container </div> </body></html> ⌨️ 快捷键说明
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