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While learning Java, I often wished there was a convenient way to find
out the constructors, methods and fields of a given Java class. Java’s
documentation is very good, of course, but you have to follow many links
before you finally reach your destination. So I took some time out and
worked on a handy solution. The Method Finder is an application that
shows you the constructors, methods and fields of a class. It greatly
helped me. I hope it will do so for you, too.
Here’s the code:
/* MethodFinder.java
* The method finder application
* developed by Kishore [kishorear@hotmail.com]
*/
import java.awt.*;
import java.awt.event.*;
import java.lang.reflect.*;
/*
* The method finder class makes an instance
* of MainFram class and shows the frame
*/
public class MethodFinder
{
public static void main(String Args[])
{ MainFrame f = new MainFrame();
f.setSize(560, 410);
f.centreForm();
f.setVisible(true);
} // end of main
} // end of MethodFinder class
and…
/* Msgbox.java
* The method finder application
*/
import java.awt.*;
import java.awt.event.*;
/* This class displays a custom message
* in a dialog box
*/
public class Msgbox extends Dialog
{ Msgbox(Frame f1, String prompt, String title)
{
super(f1, title, true);
setLayout(null);
setResizable(false);
setBackground(SystemColor.control);
// get width of prompt
FontMetrics fm = getFontMetrics(getFont());
int sw = fm.stringWidth(prompt);
setSize(sw + 50, 100);
Dimension d = getSize();
int a1 = (int) d.getWidth();
int promptLeft = (a1 - sw) / 2;
Label l1 = new Label();
l1.setText(prompt);
l1.setBounds(promptLeft, 30, sw, 20);
add(l1);
Button b1 = new Button();
b1.setLabel("OK");
b1.setBounds(0, 0, 40, 20);
int a = (int) d.getWidth();
int b = b1.getWidth();
int c = (a - b) / 2;
b1.setLocation(c, 60);
b1.addActionListener(new ActionListener()
{ public void actionPerformed(ActionEvent ae)
{ setVisible(false);
}
});
add(b1);
addWindowListener(new WindowAdapter()
{ public void windowClosing(WindowEvent we)
{ setVisible(false);
}
});
centreForm();
setVisible(true);
} // End of constructor
public void centreForm()
{ Toolkit tkMsg = getToolkit();
Dimension dimScreen = tkMsg.getScreenSize();
Dimension dimDialog = getSize();
int left = (int) (dimScreen.getWidth() - dimDialog.getWidth()) / 2;
int top = (int) (dimScreen.getHeight() - dimDialog.getHeight()) / 2;
setLocation(left, top);
} // End of centreForm
} // End of class
and…
/* MainFrame.java
* The method finder application
*/
import java.awt.*;
import java.awt.event.*;
import java.lang.reflect.*;
import java.awt.datatransfer.*;
/* This class does most of the work of
* Method Finder.
*/
class MainFrame extends Frame
{
final int HIST_COUNT = 10;
Choice chsTypes = new Choice(); // Choice to select types (constructors, fields, methods)
TextField txtClass = new TextField(); // TextField where user types the name of class
List lstValues = new List(); // List which displays then Constructors, methods or fields
TextArea txtFullString = new TextArea(); // TextArea which displays Description
Method myMethods[]; // Method array which holds info about methods of the class
Field myFields[]; // Field array which holds info about fields
Constructor myConstructors[]; // Constructor array which holds info about constructors
Button btnClose; // Button which closes the frame
Button btnHelp; // Button which shows help when clicked
Checkbox chkShowDeclaration; // Checkbox which helps user to switch between actual declaration
// and description of method
PopupMenu pm;
String arrHistory[] = new String[HIST_COUNT];
int currentHist = 0;
Button btnHistory;
PopupMenu pmHistory;
MainFrame()
{ super("Method Finder");
setLayout(null);
setResizable(false);
setBackground(SystemColor.control);
// add first label
Label l1 = new Label("Enter a Java Class (like java.awt.Dimension) and press Enter.");
l1.setBounds(20, 30, 450, 20);
add(l1);
// add txtClass
txtClass.setBounds(20, 50, 400, 20);
add(txtClass);
// add btnHistory
btnHistory = new Button(" /");
btnHistory.setBounds(400, 50, 50, 20);
add(btnHistory);
// add second label
Label l2 = new Label("Select an item from the list.");
l2.setBounds(20, 70, 450, 20);
add(l2);
// add chstypes
chsTypes.setBounds(20, 90, 450, 20);
chsTypes.add("Constructers");
chsTypes.add("Methods");
chsTypes.add("Fields");
add(chsTypes);
// add next label 'Members'
Label l3 = new Label("Members");
l3.setBounds(20, 120, 450, 20);
add(l3);
// add lstValues
lstValues.setBounds(20, 140, 450, 100);
add(lstValues);
// add label 'Description'
Label l4 = new Label("Description");
l4.setBounds(20, 250, 450, 20);
add(l4);
// add txtFullString
txtFullString.setBounds(20, 270, 450, 100);
add(txtFullString);
// add Close button
btnClose = new Button("Close");
btnClose.setBounds(480, 50, 60, 20);
add(btnClose);
// add Help button
btnHelp = new Button("Help");
btnHelp.setBounds(480, 90, 60, 20);
add(btnHelp);
// add check box 'Show Actual Declaration'
chkShowDeclaration = new Checkbox("Show Actual Declaration in Description",false);
chkShowDeclaration.setBounds(20, 380, 450, 20);
add(chkShowDeclaration);
chkShowDeclaration.setEnabled(false);
// add popup menu to lstValues
pm = new PopupMenu();
MenuItem mnuZoom = new MenuItem("Zoom...");
MenuItem mnuCopy = new MenuItem("Copy");
pm.add(mnuZoom);
pm.add(mnuCopy);
// actionperfomed event mnuCopy (copy to clipboard)
mnuCopy.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
StringSelection ss = new StringSelection(lstValues.getSelectedItem());
Toolkit tk = getToolkit();
Clipboard cp = tk.getSystemClipboard();
cp.setContents(ss, ss);
}
});
mnuZoom.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
zoomClass();
}
});
lstValues.add(pm);
// mouse released event of lstValues
lstValues.addMouseListener(new MouseAdapter()
{ public void mouseReleased(MouseEvent me)
{
// if right button is clicked
// and at lstValues has at least one item
if (me.isPopupTrigger() && lstValues.getItemCount() !=0)
{
Label tmpLbl = new Label();
add(tmpLbl);
tmpLbl.add(pm);
pm.show(tmpLbl, me.getX() + lstValues.getX(), me.getY() + lstValues.getY());
}
}
});
// actionPerformed event of lstValues
lstValues.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
zoomClass();
}
});
// add History popup menu
pmHistory = new PopupMenu();
pmHistory.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
txtClass.setText(ae.getActionCommand());
fillItems();
}
});
btnHistory.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
Label lbl1 = new Label("lbl1");
add(lbl1);
lbl1.add(pmHistory);
// add menuitems to pmHistory
pmHistory.removeAll();
//for(int i=0; i=0; i--)
{
pmHistory.add(arrHistory[i]);
}
int x = btnHistory.getX();
int y = btnHistory.getY() + btnHistory.getHeight();
pmHistory.show(lbl1, x, y);
}
});
// action performed event of txtClass
txtClass.addActionListener(new ActionListener()
{ public void actionPerformed(ActionEvent ae)
{ fillItems();
}
});
// item state changed event of chsTypes
chsTypes.addItemListener(new ItemListener()
{ public void itemStateChanged(ItemEvent ie)
{ fillItems();
}
});
// item changed event of LstValues
lstValues.addItemListener(new ItemListener()
{ public void itemStateChanged(ItemEvent ie)
{ displayFullText();
}
});
// window closing event
addWindowListener(new WindowAdapter()
{ public void windowClosing(WindowEvent we)
{ System.exit(0);
}
});
// action performed event of btnClose
btnClose.addActionListener(new ActionListener()
{ public void actionPerformed(ActionEvent ae)
{ System.exit(0);
}
});
// action performed event of btnHelp
btnHelp.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
HelpFrame helpFrame = new HelpFrame(MainFrame.this, "Help.txt");
helpFrame.showHelp();
}
});
// item state changed event of chkShowDeclaration
chkShowDeclaration.addItemListener(new ItemListener()
{ public void itemStateChanged(ItemEvent ie)
{ displayFullText();
}
});
} // End of Sample frame constructer
private void fillItems()
{
try
{
txtFullString.setText(" ");
// trim txtClass
txtClass.setText(txtClass.getText().trim());
// exit if class name is blank
if (txtClass.getText().equals(" ") || txtClass.getText().equals(""))
return;
// set cursor to hourglass
setCursor(new Cursor(Cursor.WAIT_CURSOR));
Class c;
c = Class.forName(txtClass.getText());
switch (chsTypes.getSelectedIndex())
{ case 0: // Fill Constructers
{
// add constructers to list
lstValues.removeAll();
myConstructors = c.getConstructors();
for(int i = 0; i < myConstructors.length; i++)
lstValues.add(" " + myConstructors[i].getName());
break;
}
case 1: // Fill Methods
{
// add methods to list
lstValues.removeAll();
myMethods = c.getMethods();
for(int i=0; i < myMethods.length; i++)
lstValues.add(" " + myMethods[i].getName());
break;
}
case 2: // Fill fields
{
// add fields to list
lstValues.removeAll();
myFields = c.getFields();
for (int i=0; i < myFields.length; i++)
lstValues.add(" " + myFields[i].getName());
//prevChkValue = chkShowDeclaration.getState();
break;
}
} // end of switch
// select first item from lstValues
if (lstValues.getItemCount() > 0)
{
lstValues.select(0);
displayFullText();
chkShowDeclaration.setEnabled(true);
}
else
chkShowDeclaration.setEnabled(false);
// add to history array
addToHistory();
setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
} catch (ClassNotFoundException e) // catch class not found exception
{
lstValues.removeAll();
txtFullString.setText(" ");
chkShowDeclaration.setEnabled(false);
Msgbox m1 = new Msgbox(this, "Invalid Class Name", "Method Finder");
setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
}
catch (Exception e) // catch other exceptions
{
lstValues.removeAll();
txtFullString.setText(" ");
chkShowDeclaration.setEnabled(false);
Msgbox m1 = new Msgbox(this, "Error" + e, "Method Finder");
setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
}
} // end of fill items
private void displayFullText()
{
switch (chsTypes.getSelectedIndex())
{ case 0: // constructors
{ Constructor tmpCon = myConstructors[lstValues.getSelectedIndex()];
if (chkShowDeclaration.getState())
txtFullString.setText(" " + tmpCon);
else
displayConstructorInfo(tmpCon);
break;
}
case 1: // methods
{ Method tmpMet = myMethods[lstValues.getSelectedIndex()];
if (chkShowDeclaration.getState())
txtFullString.setText(" " + tmpMet);
else
displayMethodInfo(tmpMet);
break;
}
case 2: // fields
{ Field tmpFie = myFields[lstValues.getSelectedIndex()];
if (chkShowDeclaration.getState())
txtFullString.setText(" " + tmpFie);
else
displayFieldInfo(tmpFie);
break;
}
} // end of switch
} // end of displayFullText
private void displayConstructorInfo(Constructor tmpCon)
{
// get name of constructor
//String desc = "Name : " + tmpCon.getName();
// get parameters of constructor
String desc = "Parameters :- n";
Class p[] = tmpCon.getParameterTypes();
for (int i=0; i < p.length; i++)
desc += "t" + p[i] + "n";
// get modifiers
desc += "Modifiers :-n";
int x = tmpCon.getModifiers();
desc += getModifierString(x);
// get exception types
desc += "Exception Types :-n";
Class e[] = tmpCon.getExceptionTypes();
for (int i=0; i < e.length; i++)
desc += "t" + e[i] + "n";
// display information
txtFullString.setText(desc);
} // end of displayConstructorInfo
private void displayMethodInfo(Method tmpMet)
{
// get parameter types of method
String desc = "Parameters :-n";
Class p[] = tmpMet.getParameterTypes();
for (int i=0; i < p.length; i++)
desc += "t" + p[i] + "n";
// get return type
desc += "Return Type :-nt" + tmpMet.getReturnType() + "n";
// get modifiers
desc += "Modifiers :-n";
int x = tmpMet.getModifiers();
desc += getModifierString(x);
// get exception types
desc += "Exception Types :-n";
Class e[] = tmpMet.getExceptionTypes();
for (int i=0; i < e.length; i++)
desc += "t" + e[i] + "n";
// display information
txtFullString.setText(desc);
} // end of displayMethodInfo
private void displayFieldInfo(Field tmpField)
{ String desc;
// get modifiers
desc = "Modifiers :-n";
int x = tmpField.getModifiers();
desc += getModifierString(x);
// display information
txtFullString.setText(desc);
} // end of displayFieldInfo
private String getModifierString(int x)
{ String strModifier = "";
if (Modifier.isAbstract(x)) // abstract
strModifier += "tabstractn";
if (Modifier.isFinal(x)) // final
strModifier += "tfinaln";
if (Modifier.isInterface(x)) // interface
strModifier += "tinterfacen";
if (Modifier.isNative(x)) // native
strModifier += "tnativen";
if (Modifier.isPrivate(x)) // private
strModifier += "tprivaten";
if (Modifier.isProtected(x)) // protected
strModifier += "tprotectedn";
if (Modifier.isPublic(x)) // public
strModifier += "tpublicn";
if (Modifier.isStatic(x)) // static
strModifier += "tstaticn";
if (Modifier.isStrict(x)) // strict
strModifier += "tstrictn";
if (Modifier.isSynchronized(x)) // synchronized
strModifier += "tsynchronizedn";
if (Modifier.isTransient(x)) // transient
strModifier += "ttransientn";
if (Modifier.isVolatile(x)) // volatile
strModifier += "tvolatilen";
return(strModifier);
} // end of getModifierString
public void addToHistory()
{ boolean existing = false;
// check if existing
for(int i=0; i= HIST_COUNT)
{
for(int i=0; i < (HIST_COUNT-1); i++)
arrHistory[i] = arrHistory[i+1];
currentHist--;
}
arrHistory[currentHist++] = txtClass.getText();
}
} // end of addToHistory
private void zoomClass()
{
String zoomText = "nClass :- nt" + txtClass.getText();
zoomText += "nMember :- nt" + lstValues.getSelectedItem();
zoomText += "n" + txtFullString.getText();
ZoomFrame zf = new ZoomFrame(MainFrame.this, zoomText);
zf.zoom();
}
public void centreForm()
{
Toolkit tkMsg = getToolkit();
Dimension dimScreen = tkMsg.getScreenSize();
Dimension dimDialog = getSize();
int left = (int) (dimScreen.getWidth() - dimDialog.getWidth()) / 2;
int top = (int) (dimScreen.getHeight() - dimDialog.getHeight()) / 2;
setLocation(left, top);
} // End of centreForm
} // end of MainFrame class
plus...
import java.awt.*;
import java.awt.event.*;
import java.io.FileInputStream;
public class HelpFrame extends Frame
{ private TextArea txtDesc; // TextArea which displays contents of help.txt
final int INDENT = 25; // set top margin
private byte readBytes[]; // holds the bytes read from help.txt
public HelpFrame(Frame frm, String fileName)
{ super("Help"); // call constructor of dialog
setLayout(new BorderLayout());
setBackground(SystemColor.control);
setSize(400, 400);
centreForm();
try
{
// read from help.txt
FileInputStream fHelp = new FileInputStream(fileName);
int totBytes = fHelp.available();
readBytes = new byte[totBytes];
fHelp.read(readBytes, 0, totBytes);
fHelp.close();
String s1 = "";
txtDesc = new TextArea("", 0, 0 , TextArea.SCROLLBARS_VERTICAL_ONLY);
// pass bytes to txtDesc
for (int i=0; i<totBytes; i++)
{
s1 += (char) readBytes[i];
}
txtDesc.setText(s1);
} catch (Exception e)
{
System.out.println(" " + e);
}
txtDesc.setEditable(false);
add(txtDesc, BorderLayout.CENTER);
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent we)
{
setVisible(false);
}
});
}
public void zoom()
{
setVisible(true);
}
private void centreForm()
{
Toolkit tkMsg = getToolkit();
Dimension dimScreen = tkMsg.getScreenSize();
Dimension dimDialog = getSize();
int left = (int) (dimScreen.getWidth() - dimDialog.getWidth()) / 2;
int top = (int) (dimScreen.getHeight() - dimDialog.getHeight()) / 2;
setLocation(left, top);
} // End of centreForm
public void showHelp()
{
setVisible(true);
}
}
and finally...
/* Msgbox.java
* The method finder application
*/
import java.awt.*;
import java.awt.event.*;
public class ZoomFrame extends Frame
{ TextArea txtDesc;
final int INDENT = 25;
public ZoomFrame(Frame frm, String s1)
{ super("Zoom");
setLayout(new BorderLayout());
setBackground(SystemColor.control);
setSize(400, 400);
centreForm();
txtDesc = new TextArea("", 0, 0 , TextArea.SCROLLBARS_VERTICAL_ONLY);
txtDesc.setText(s1);
add(txtDesc, BorderLayout.CENTER);
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent we)
{
setVisible(false);
}
});
}
public void zoom()
{
setVisible(true);
}
private void centreForm()
{
Toolkit tkMsg = getToolkit();
Dimension dimScreen = tkMsg.getScreenSize();
Dimension dimDialog = getSize();
int left = (int) (dimScreen.getWidth() - dimDialog.getWidth()) / 2;
int top = (int) (dimScreen.getHeight() - dimDialog.getHeight()) / 2;
setLocation(left, top);
} // End of centreForm
}
Downloads
About the Author
Kishore Ar works for Thomson Cyber Solutions Pvt. Ltd, Trivandrum,
Kerala, India as a senior programmer. He says that programming is his
profession and hobby. He has been involved in many projects, both Web-based
and client/server, for the last four years especially designing and
developing database projects using Java, Visual Basic 6, and
Oracle 8i. He can be contacted at kishorear@hotmail.com.
[To contribute a code article to Gamelan, please contact
kmurphy@internet.com.]
