warshall

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 */
package placeholder;



import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.ScrollPaneConstants;

public class WarshallProgram extends JFrame implements ActionListener {

    JLabel titleLabel;
    JTextField input[][] = new JTextField[4][4];
    JButton computeBtn;
    JButton clearBtn;
    JScrollPane scroll;
    JTextArea resultArea;
    String result = "";

    public WarshallProgram() {
        super("Warshall Program");
        setLayout(null);
        int r = 20;
        titleLabel = new JLabel("Warshall Algorithm");
        computeBtn = new JButton("Calculate");
        clearBtn = new JButton("Clear");
        resultArea = new JTextArea("");
        scroll = new JScrollPane(resultArea);
        scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

        titleLabel.setBounds(20, 20, 500, 20);
        computeBtn.setBounds(300, 75, 100, 40);
        clearBtn.setBounds(300, 150, 100, 40);
        scroll.setBounds(20, 225, 400, 150);
        resultArea.setLineWrap(true);
        resultArea.setWrapStyleWord(true);
        resultArea.setEditable(false);

        for (int i = 0; i < 4; i++) {
            int c = 0;
            r += 40;
            for (int j = 0; j < 4; j++) {
                c += 60;
                input[i][j] = new JTextField("");
                input[i][j].setBounds(c, r, 30, 25);
                add(input[i][j]);
                if(i==j){
                    input[i][j].setText("0");
                    input[i][j].setEditable(false);
                }
            }
        }

        add(clearBtn);
        add(titleLabel);
        add(computeBtn);
        add(scroll);

        clearBtn.addActionListener(this);
        computeBtn.addActionListener(this);
        setVisible(true);
        setSize(475, 450);
        setLocation(300, 100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == computeBtn) {
            int n=0;
            for(int i=0; i<4; i++){
                for(int j=0; j<4; j++){
                    if ((input[i][j].getText().equals("1")) || (input[i][j].getText().equals("0"))){
                        n+=1;
                    }
                }
            }

            if(n!=16){
                JOptionPane.showMessageDialog(this, "Invalid input. Please enter 1 or 0 only.",
                    "Error", JOptionPane.ERROR_MESSAGE);
            }
            else{
                result = "Result: \n";
                int inputs[][] = new int[4][4];
                for(int i=0; i<4; i++){
                    for(int j=0; j<4; j++){
                       inputs[i][j] = Integer.parseInt(input[i][j].getText());
                    }
                }

                //for testing
                //int sample[][] = {{0, 0, 1, 0}, {1, 0, 0, 1}, {0, 0, 0, 0}, {0, 1, 0, 0}};
                WarshallSolution(inputs, 4);
                resultArea.setText(result);
            }
        }
        if (e.getSource() == clearBtn) {
            for (int i = 0; i < 4; i++) {
                for (int j = 0; j < 4; j++) {
                    input[i][j].setText("");
                }
            }
            input[0][0].setText("0");
            input[1][1].setText("0");
            input[2][2].setText("0");
            input[3][3].setText("0");
            result = "";
            resultArea.setText(result);
        }
    }

    public static void main(String[] args) {
        Placeholder wp = new Placeholder();
        wp.setVisible(true);
    }

    /**
     * This method holds the process for the Warshall Algorithm.
     * @param inputs  array - user input of matrix
     * @param size  size of the matrix
     */
    public void WarshallSolution(int[][] inputs, int size) {

        //displaying the original input
        result += "R(" + 0 + "):\n";
        for (int j = 0; j < 4; j++) {
            for (int k = 0; k < 4; k++) {
                result += inputs[j][k] + "\t";
            }
            result+="\n";
        }
        result+="\n\n";

        //warshall algo process
        warshall(0,inputs,size);

    }
    public void warshall(int n, int[][] inputs,int size){
        if(n==size){

            return;
        }
        for (int r = 0; r < size; r++) {
            if (r == n) {
                continue;
            }
            for (int c = 0; c < size; c++) {
                if (c == n) {
                    continue;
                }
                int prod = inputs[r][n] * inputs[n][c];
                if ((prod == 1 || inputs[r][c] == 1)) {
                    inputs[r][c] = 1;
                }
            }
        }
        result += "R(" + (n + 1) + "):\n";
        for (int j = 0; j < 4; j++) {
            for (int k = 0; k < 4; k++) {
                result += inputs[j][k] + "\t";
            }
            result += "\n";
        }
        result += "\n\n";
        warshall(n+1,inputs,size);
    }

}