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I'm new to Java GUI. I'm having a trouble visualizing bubble sort algorithm. I'm going to have to prompt a user to type an array of numbers, and sort that array using bubble sort.

I have the code in the link below, consisting of ActionListener class, which is triggered after user finishing to input their arrays. I got the program working, but the thing is, I cannot "View" the ongoing graphics. The graphics should display the ongoing sorting of rectangular bar, but all I see is the sorted result. Could anyone please help me on what I am doing wrong here?

`    //The BubbleListener class will implement buttons chosen by player
private class BubbleListener implements ActionListener{
    //Graphics g = frame.getGraphics();
    public void actionPerformed(ActionEvent e) {
        frame = new JFrame("Sorting Algorithm Visualiser");
        frame.setSize(800, 800);
        //g = frame.getGraphics();
        bubbleLabel.setText("<html><b><div style='text-align: left'>Please input an array of numbers to be bubble-sorted separated by comma: </b></div></html");
        
        textInput = new JTextField(15);
        textInput.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                input = textInput.getText();   //receive input from text field
                String[] splitArr=input.split(","); //
                splitNum=new int[splitArr.length];
                for (int i=0; i<splitArr.length; i++) {
                    System.out.print(splitNum[i]=Integer.parseInt(splitArr[i]));
                    System.out.print(' ');
                }
                System.out.println(input);
                System.out.println("Testing input");
               
                for(int i = 0;i<splitNum.length-1;i++){
                    g = frame.getGraphics();
                    g.setColor(Color.WHITE);
                    g.fillRect(50, 200, 700, 700);
                    
                    //Bubble sort algorithm
                    for(int j = 0;j<splitNum.length-i-1;j++){
                        if(splitNum[j]>splitNum[j+1]){
                            int temp = splitNum[j];
                            splitNum[j] = splitNum[j+1];
                            splitNum[j+1] = temp;
                            //splitNum[j+1]=(splitNum[j+1]+splitNum[j])-(splitNum[j]=splitNum[j+1]);                   
                        }
                    }
                    
                    //Printing the array
                    for(int k = 0;k<splitNum.length;k++){
                        g.setColor(Color.BLACK) ;
                        g.fillRect(100+50*k,500-splitNum[k]*30,30,splitNum[k]*30);
                        g.drawString(""+splitNum[k],100+50 * k,530);
                    }
                    System.out.println(Arrays.toString(splitNum));
                    try { 
                        Thread.sleep(1000);
                    } catch (InterruptedException e1) {
                        // TODO Auto-generated catch block
                        e1.printStackTrace();
                    }
                }
            }
        });
        
        /*Set form properties*/
        FlowLayout fl = new FlowLayout();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    //Shut down process
        frame.setLayout(fl);            //Set up flow layout
        frame.setResizable(false);      //Cannot change form size
        //frame.pack();
        frame.setLocationRelativeTo(null);//Center display
        bubblePanel.add(bubbleLabel);
        bubblePanel.add(textInput);
        
        bubbleVal = textInput.getText();
        String [] bubbleSplit = bubbleVal.split(",");
        
        frame.getContentPane().add(bubblePanel);
        frame.setVisible(true);
    }
} `
Hovercraft Full Of Eels
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djonemesis
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  • There are many things wrong here including: using `frame.getGraphics()` to get a graphics object, drawing with this unstable object, using `Thread.sleep` in a Swing GUI,... You will want to scrap this code and instead, 1) Use a Swing Timer to increment the *state* of your program over time (to change key variables each time its ActionListener is called), 2) draw within a paintComponent method of a class that extends JPanel, 3) use the Graphics object that the JVM gives you inside the paintComponent method 4) Never sleep the Swing event thread... – Hovercraft Full Of Eels Mar 06 '22 at 03:56
  • Key links: 1) [Swing Timer](http://docs.oracle.com/javase/tutorial/uiswing/misc/timer.html), 2) [Lesson: Concurrency in Swing](http://docs.oracle.com/javase/tutorial/uiswing/concurrency/), 3) [Lesson: Performing Custom Painting](http://docs.oracle.com/javase/tutorial/uiswing/painting/index.html). – Hovercraft Full Of Eels Mar 06 '22 at 03:58
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    Check out [Bubble Sort Animation](https://stackoverflow.com/questions/64196198/bubble-sort-animation) for a couple of different approaches. – camickr Mar 06 '22 at 04:08

0 Answers0