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import
javax.swing.*;
import java.awt.*;
import java.awt.event.*;
/**
* Count the number of non-zero elements in a
matrix by
* assigning instances of the MatHunter class
to search
* each quadrant.
**/
public class TaskSplitApplet extends JApplet
implements Outputable, ActionListener
{
// A Swing textarea for display of string info
JTextArea fTextArea;
/**
* Create a User Interface with a
textarea with scroll bars
* and a Go button to initiate processing
and a Clear button
* to clear the textarea.
**/
public void init () {
Container content_pane = getContentPane
();
JPanel panel = new JPanel (new BorderLayout
());
// Create a text area.
fTextArea = new JTextArea ();
// Make it editable
fTextArea.setEditable (false);
// Add to a scroll pane so that
a long list of
// computations can be seen.
JScrollPane area_scroll_pane = new
JScrollPane (fTextArea);
panel.add (area_scroll_pane,BorderLayout.CENTER);
JButton go_button = new JButton
("Go");
go_button.addActionListener (this);
JButton clear_button = new JButton
("Clear");
clear_button.addActionListener (this);
JPanel control_panel = new JPanel
();
control_panel.add (go_button);
control_panel.add (clear_button);
panel.add (control_panel,BorderLayout.SOUTH);
// Add text area & control panel.
content_pane.add (panel);
} // init
/** Respond to the buttons to start the threads
or to clear
* the text area.
**/
public void actionPerformed (ActionEvent e)
{
if (e.getActionCommand ().equals
("Go"))
start ();
else
fTextArea.setText
(null);
} // actionPerformed
/** Create 4 MatHunter threads to scan sections
of the
* matrix for non-zero elements.
**/
public void start () {
int [][] intMat = new int[2000][2000];
// Fill matrix elements with either
0 or 1 randomly chosen.
for (int i=0; i<2000; i++) {
for (int j=0; j<2000;
j++) {
if (Math.random
() >0.5) intMat[i][j] = 1;
}
}
// Create a MatHunter for each quadrant
of the matrix
MatHunter mh1 = new MatHunter (intMat,0,999,0,999,this);
MatHunter mh2 = new MatHunter (intMat,0,999,1000,1999,this);
MatHunter mh3 = new MatHunter (intMat,1000,1999,0,999,this);
MatHunter mh4 = new MatHunter (intMat,1000,1999,1000,1999,this);
println ("Start:");
mh1.start ();
mh2.start ();
mh3.start ();
mh4.start ();
} // start
/** Overided Outputable println to send string
to text area.**/
public void println (String str) {
fTextArea.append (str + CR);
}
/** Overided Outputable print to send string
to text area.**/
public void print (String str) {
fTextArea.append (str);
}
} // class TaskSplitApplet
/** Thread
class to count the number of non-zero elements
* in a section of a matrix.
**/
class MatHunter extends Thread {
int [][] fMatrix;
int fIlo,fIhi,fJlo,fJhi;
int fOnes = 0;
Outputable fOutput;
/** Constructor gets the matrix and the indices
specifying
* what section to examine.
**/
MatHunter (int [][] int_mat,
int
i1,int i2,int j1, int j2,
Outputable
out) {
fIlo=i1; fIhi=i2;
fJlo=j1; fJhi=j2;
fMatrix = int_mat;
fOutput = out;
} // ctor
/** Scan a section of a 2-D matrix and
* count the number of non-zero elements.
**/
public void run () {
for (int i=fIlo; i <= fIhi; i++)
{
for (int j=fJlo; j <=
fJhi; j++) {
if ( fMatrix[i][j]
> 0) fOnes++;
}
yield ();
}
fOutput.println (" #
ones = " + fOnes + " for i = "+
fIlo +"
to " + fIhi + " & j = " + fJlo +" to " + fJhi);
} // run
} // class MatHunter
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