理解Java
前言:没事在看《Java Swing, 2nd Edition》，看到有个东西还是蛮有趣的说，就是Accelerator key，呵呵，好像要配合Alt一起用才能起到作用。蛮多东西是看了程序后才发现原文的意思的。这次算是插曲，不在MapsEditor的范围之内。顺便提一下，中午起来有3到4个人加了群，蛮开心的。高手也好初学也罢，大家重要的是交流，大胆说出自己的想法，错了就错了，谁没错过啊……关于Accelerator key，在做GUI的时候还是比较重要的吧，至少以前认为那些不用鼠标的人蛮高手的，呵呵，自己也会去刻意记些常用的快捷键，在Windows下用用还算凑合那，呵呵。程序是从书上搬下来的，觉得蛮有意思的，大家可以看看。
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// MnemonicLabels.java
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//
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import javax.swing.*;
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import java.awt.*;
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// Shows how displayedMnemonic and labelFor properties work together
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public class MnemonicLabels ...{
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public static void main(String[] args) ...{
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JTextField firstField = new JTextField(10);
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JTextField middleField = new JTextField(10);
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JTextField lastField = new JTextField(10);
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// Create labels and mnemonics.
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JLabel firstLabel = new JLabel("First Name", JLabel.RIGHT);
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firstLabel.setDisplayedMnemonic('F');
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firstLabel.setLabelFor(firstField);
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JLabel middleLabel = new JLabel("Middle Initial", JLabel.RIGHT);
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middleLabel.setDisplayedMnemonic('I');
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middleLabel.setDisplayedMnemonicIndex(7); // Requires 1.4
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middleLabel.setLabelFor(middleField);
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JLabel lastLabel = new JLabel("Last Name", JLabel.RIGHT);
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lastLabel.setDisplayedMnemonic('L');
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lastLabel.setLabelFor(lastField);
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// Layout and display
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JPanel p = new JPanel( );
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p.setLayout(new GridLayout(3, 2, 5, 5));
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p.add(firstLabel);
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p.add(firstField);
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p.add(middleLabel);
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p.add(middleField);
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p.add(lastLabel);
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p.add(lastField);
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JFrame f = new JFrame("MnemonicLabels");
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f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
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f.setContentPane(p);
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f.pack( );
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f.setVisible(true);
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}
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}
有Java环境的可以拷贝去然后编译运行看看，然后分别按Alt F、Alt I、Alt L，Foucs就会在三个TextField之间转换。关键的是firstLabel.setDisplayedMnemonic('F')和firstLabel.setLabelFor(firstField)，前一个setDisplayedMnemonic(char)选定哪个character为快捷键，就像VC里面的“&”一样的功能，而后面这个setLabelFor(comp)则表明你按下相应的快捷键(加速键)后焦点定位到哪个控件上(当然要有焦点的控件)。需要注意的是第二个快捷键的设置“middleLabel.setDisplayedMnemonicIndex(7);”这个需要SDK1.4的支持，这个的作用就是设置显示的下划线为第几个字符。很明显，我们注意到对于“I”来说，“Middle Initial”中前后有两个“I”，而这里是部分大小写的，所以按照第一个或者第三个的做法的话，程序会默认JLabel中文字满足的第一个字符加下划线，也就是这个样子了“Middle Initial”，我们要的是“Middle Initial”的效果，所以把下划线设置到第七个字符“I”上面。其他也没什么好玩的了，除了这个应该都能摸索懂吧，呵呵。
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