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<a href="http://www.bruceeckel.com/javabook.html">Bruce Eckel's Thinking in Java</a>
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<a href="tij_c.html">Contents</a> | <a href="tij0185.html">Prev</a> | <a href="tij0187.html">Next</a>
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<H2 ALIGN=LEFT>
A
method lookup tool
<P><A NAME="Index3062"></A></H2>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Chapter
11 introduced the Java 1.1 concept of <A NAME="Index3063"></A><A NAME="Index3064"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><I>reflection</I></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and used that feature to look up methods for a particular class &#8211; either
the entire list of methods or a subset of those whose names match a keyword you
provide. The magic of this is that it can automatically show you 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><I>all</I></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
the methods for a class without forcing you to walk up the inheritance
hierarchy examining the base classes at each level. Thus, it provides a
valuable timesaving tool for programming: because the names of most Java method
names are made nicely verbose and descriptive, you can search for the method
names that contain a particular word of interest. When you find what you think
you&#8217;re looking for, check the online documentation.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">However,
by Chapter 11 you hadn&#8217;t seen the AWT, so that tool was developed as a
command-line application. Here is the more useful GUI version, which
dynamically updates the output as you type and also allows you to cut and paste
from the output:
</FONT><P></DIV>

<font color="#990000"><PRE><font color="#009900">//: DisplayMethods.java</font>
<font color="#009900">// Display the methods of any class inside</font>
<font color="#009900">// a window. Dynamically narrows your search.</font>
<font color="#0000ff">import</font> java.awt.*;
<font color="#0000ff">import</font> java.awt.event.*;
<font color="#0000ff">import</font> java.applet.*;
<font color="#0000ff">import</font> java.lang.reflect.*;
<font color="#0000ff">import</font> java.io.*;

<font color="#0000ff">public</font> <font color="#0000ff">class</font> DisplayMethods <font color="#0000ff">extends</font> Applet {
  Class cl;
  Method[] m;
  Constructor[] ctor;
  String[] n = <font color="#0000ff">new</font> String[0];
  TextField 
    name = <font color="#0000ff">new</font> TextField(40),
    searchFor = <font color="#0000ff">new</font> TextField(30);
  Checkbox strip = 
    <font color="#0000ff">new</font> Checkbox("Strip Qualifiers");
  TextArea results = <font color="#0000ff">new</font> TextArea(40, 65);
  <font color="#0000ff">public</font> <font color="#0000ff">void</font> init() {
    strip.setState(<font color="#0000ff">true</font>);
    name.addTextListener(<font color="#0000ff">new</font> NameL());
    searchFor.addTextListener(<font color="#0000ff">new</font> SearchForL());
    strip.addItemListener(<font color="#0000ff">new</font> StripL());
    Panel 
      top = <font color="#0000ff">new</font> Panel(),
      lower = <font color="#0000ff">new</font> Panel(),
      p = <font color="#0000ff">new</font> Panel();
    top.add(<font color="#0000ff">new</font> Label("Qualified <font color="#0000ff">class</font> name:"));
    top.add(name);
    lower.add(
      <font color="#0000ff">new</font> Label("String to search <font color="#0000ff">for</font>:"));
    lower.add(searchFor);
    lower.add(strip);
    p.setLayout(<font color="#0000ff">new</font> BorderLayout());
    p.add(top, BorderLayout.NORTH);
    p.add(lower, BorderLayout.SOUTH);
    setLayout(<font color="#0000ff">new</font> BorderLayout());
    add(p, BorderLayout.NORTH);
    add(results, BorderLayout.CENTER);
  }
  <font color="#0000ff">class</font> NameL <font color="#0000ff">implements</font> TextListener {
    <font color="#0000ff">public</font> <font color="#0000ff">void</font> textValueChanged(TextEvent e) {
      String nm = name.getText().trim();
      <font color="#0000ff">if</font>(nm.length() == 0) {
        results.setText("No match");
        n = <font color="#0000ff">new</font> String[0];
        <font color="#0000ff">return</font>;
      }
      <font color="#0000ff">try</font> {
        cl = Class.forName(nm);
      } <font color="#0000ff">catch</font> (ClassNotFoundException ex) {
        results.setText("No match");
        <font color="#0000ff">return</font>;
      }
      m = cl.getMethods();
      ctor = cl.getConstructors();
      <font color="#009900">// Convert to an array of Strings:</font>
      n = <font color="#0000ff">new</font> String[m.length + ctor.length];
      <font color="#0000ff">for</font>(<font color="#0000ff">int</font> i = 0; i &lt; m.length; i++)
        n[i] = m[i].toString();
      <font color="#0000ff">for</font>(<font color="#0000ff">int</font> i = 0; i &lt; ctor.length; i++)
        n[i + m.length] = ctor[i].toString();
      reDisplay();
    }
  }
  <font color="#0000ff">void</font> reDisplay() {
    <font color="#009900">// Create the result set:</font>
    String[] rs = <font color="#0000ff">new</font> String[n.length];
    String find = searchFor.getText();
    <font color="#0000ff">int</font> j = 0;
    <font color="#009900">// Select from the list if find exists:</font>
    <font color="#0000ff">for</font> (<font color="#0000ff">int</font> i = 0; i &lt; n.length; i++) {
      <font color="#0000ff">if</font>(find == <font color="#0000ff">null</font>)
        rs[j++] = n[i];
      <font color="#0000ff">else</font> <font color="#0000ff">if</font>(n[i].indexOf(find) != -1)
          rs[j++] = n[i];
    }
    results.setText("");
    <font color="#0000ff">if</font>(strip.getState() == <font color="#0000ff">true</font>)
      <font color="#0000ff">for</font> (<font color="#0000ff">int</font> i = 0; i &lt; j; i++)
        results.append(
          StripQualifiers.strip(rs[i]) + "\n");
    <font color="#0000ff">else</font> <font color="#009900">// Leave qualifiers on</font>
      <font color="#0000ff">for</font> (<font color="#0000ff">int</font> i = 0; i &lt; j; i++)
        results.append(rs[i] + "\n");
  }
  <font color="#0000ff">class</font> StripL <font color="#0000ff">implements</font> ItemListener {
    <font color="#0000ff">public</font> <font color="#0000ff">void</font> itemStateChanged(ItemEvent e) {
      reDisplay();
    }
  }
  <font color="#0000ff">class</font> SearchForL <font color="#0000ff">implements</font> TextListener {
    <font color="#0000ff">public</font> <font color="#0000ff">void</font> textValueChanged(TextEvent e) {
      reDisplay();
    }
  }
  <font color="#0000ff">public</font> <font color="#0000ff">static</font> <font color="#0000ff">void</font> main(String[] args) {
    DisplayMethods applet = <font color="#0000ff">new</font> DisplayMethods();
    Frame aFrame = <font color="#0000ff">new</font> Frame("Display Methods");
    aFrame.addWindowListener(
      <font color="#0000ff">new</font> WindowAdapter() {
        <font color="#0000ff">public</font> <font color="#0000ff">void</font> windowClosing(WindowEvent e) {
          System.exit(0);
        }
      });
    aFrame.add(applet, BorderLayout.CENTER);
    aFrame.setSize(500,750);
    applet.init();
    applet.start();
    aFrame.setVisible(<font color="#0000ff">true</font>);
  }
}

<font color="#0000ff">class</font> StripQualifiers {
  <font color="#0000ff">private</font> StreamTokenizer st;
  <font color="#0000ff">public</font> StripQualifiers(String qualified) {
      st = <font color="#0000ff">new</font> StreamTokenizer(
        <font color="#0000ff">new</font> StringReader(qualified));
      st.ordinaryChar(' ');
  }
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