Question
For this program I want to implement an array of sorting and searching algorithms. The array will be filled with random numbers. Then I want to draw each array element as a bar (making something like a bar graph). I have a step and run button in the GUI the step is supposed to use selection sort. The problem I am having is: I only know how to do selection sort with a loop. However, I can not use a loop because I have to show the array being sorted step by step. Can anyone show me how to do selection sort without a loop? I will be adding all of the code I have so far because this is my first time posting anything, and I want to make sure I am specific.
ArrayViewer:
https://stackoverflow.com/questions/16123487
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Russianimport javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import java.util.Scanner;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class ArrayViewer
{
static int[] array;
static int size;
public static void main(String[] args)
{
Scanner in=new Scanner(System.in);
//ask for the size of the array until the user enters a size in the right range
do
{
System.out.print("Enter the size of the array (should be between 10 and 80): ");
size=in.nextInt();
}
while (size<10 || size>80);
array= ArrayUtil.randomIntArray(size,100);//create a random array of given size and entries ranging from 0 to 100
final ArrayComponent arrayComp= new ArrayComponent(array); //construct an arrayComponent with the random array
class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
//I want the selection sort algorithm to go in here so I can just assign this to my stepButton.
}
}
final JFrame frame=new JFrame("Sorting"); //create and setup the frame
frame.setSize(1200,300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel buttonPanel= new JPanel(); // panel to hold the buttons
JPanel panel=new JPanel(new BorderLayout()); // panel to hold the button panel and the array component; uses BorderLayout: read about it in the API
JButton stepButton=new JButton("Step"); //button to go through the algorithm step by step
JButton runButton=new JButton("Run"); //button to run the algorithm
ActionListener listener = new ButtonListener();
stepButton.addActionListener(listener);
buttonPanel.add(stepButton);
buttonPanel.add(runButton);
panel.add(buttonPanel,BorderLayout.PAGE_START); //add the buttonPanel at the top of the panel
panel.add(arrayComp,BorderLayout.CENTER); //add the arraycoponent object in the center of teh panel
frame.add(panel);
frame.setVisible(true);
//print the entries in the array
//System.out.println(arrayComp);
}
}
ArrayComponent:
import javax.swing.JComponent;
import java.awt.Rectangle;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Dimension;
import java.awt.Color;
public class ArrayComponent extends JComponent
{
private int[] theArray;
final int dx=6; //the width of thebars (as well as the with of the spaces between bars)
private int space=0;
int index1 =0;
int index2 =0;
public ArrayComponent(int[] a)
{
theArray=a;
space=600-12*theArray.length/2; //space amount on the horizontal axes to center the graph
//600 is the frame width in the viewer program
//For each bar 12 units on the horixzontal axis is used including the space following it.
//something.addActionListener(new ButtonListener());
}
public void setIndices(int i, int j)
{
index1 = i;
index2= j;
}
public void paintComponent(Graphics g)
{
Graphics2D pen= (Graphics2D) g;
for (int k=0;k<theArray.length;k++)
{
pen.drawRect(space+2*k*dx,5,dx,theArray[k]);
//space: initial space
//2*k*dx: the (horizontal) distance of te kth bar from the start of the graph
//5: bars are located on y=5
//dx: the width of the bars
//theArray[k]: height of the kth bar
}
pen.fillRect(space+2*index1*dx,5,dx,theArray[index1]);
pen.fillRect(space+2*index2*dx,5,dx,theArray[index2]);
}
public String toString()
{
String str=("array=[");
int k=0;
for (k=0;k<theArray.length-1;k++)
str=str+theArray[k]+", ";
str=str+theArray[k]+"]";
return str;
}
}
ArrayUtil(creates the random array):
import java.util.Random;
/**
This class contains utility methods for array manipulation.
*/
public class ArrayUtil
{
private static Random generator = new Random();
/**
Creates an array filled with random values.
@param length the length of the array
@param n the number of possible random values
@return an array filled with length numbers between
0 and n - 1
*/
public static int[] randomIntArray(int length, int n)
{
int[] a = new int[length];
for (int i = 0; i < a.length; i++)
a[i] = generator.nextInt(n);
return a;
}
}
Sorry if the post is lengthy. The program already draws the arrays, it just does not sort them. Thanks for the help.
Solution
Let activeIndex refer to the index of the array element to be sorted next (starting with value 0).
Write a method, say stepSelectionSort, which will execute only the one step of selection sort and return. The sorting begins at array[activeIndex].
{5,4,3,2,1} -> activeIndex=0 -> Step.click -> stepSelectionSort() sorts array element at 0 -> {1,4,3,2,5} -> draw() -> activeIndix=1 -> Step.click -> stepSelectionSort() sorts array element 1.
OTHER TIPS
