[hardwired]

Code:

//  <applet code="TA" width="400" height="400"></applet>
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.text.NumberFormat;

public class TA extends Applet implements ActionListener {

    private Label lblSideA, lblSideB, lblSideC,
                  lblAngles, lblArea, lblRightAngle;
    private TextField txtSideA, txtSideB, txtSideC;
    NumberFormat nf;
    
    public void init() {
        nf = NumberFormat.getInstance();
        nf.setMaximumFractionDigits(2);
        setLayout(null);
        setupGUIComponents();
        final int WIDTH = 470, HEIGHT = 220;
        setSize(WIDTH, HEIGHT);
    }
    
    public void actionPerformed(ActionEvent ae) {
        String command = ae.getActionCommand();
        int a = Integer.parseInt(txtSideA.getText().trim());
        int b = Integer.parseInt(txtSideB.getText().trim());
        int c = Integer.parseInt(txtSideC.getText().trim());
        double[] angles = getAngles(a, b, c);
        
        lblAngles.setText("Three angles are " + 
                           nf.format(angles[0]) + " degree, " +
                           nf.format(angles[1]) + " degree and " +
                           nf.format(angles[2]) + " degree");
        lblArea.setText("Area of the triangle is " +
                         nf.format(getArea(a, b, c)) + " " + command);
        String s = isRightTriangle(angles) ? "" : "not ";
        lblRightAngle.setText("It is " + s + "a right triangle");
    }

    private void setupGUIComponents() {
        // initiaze the components
        Label lblInstructions =
            new Label("Enter the length of the sides of a triangle");
        Label lblSideA = new Label("a");  txtSideA = new TextField(5);
        Label lblSideB = new Label("b");  txtSideB = new TextField(5);
        Label lblSideC = new Label("c");  txtSideC = new TextField(5);
        Label lblSelect = new Label("Select unit:");
        Button btnCM = new Button("cm");
        Button btnM = new Button("m");
        Button btnKM = new Button("km");
        lblAngles = new Label();
        lblArea = new Label();
        lblRightAngle = new Label();

        // add action-listeners to the buttons
        btnCM.addActionListener(this); 
        btnM.addActionListener(this);
        btnKM.addActionListener(this);

        // allign the components to the frame
        lblInstructions.setBounds(100,10,250,20);
        lblSideA.setBounds(100,35,20,20); txtSideA.setBounds(220,35,115,20);
        lblSideB.setBounds(100,55,20,20); txtSideB.setBounds(220,55,115,20);
        lblSideC.setBounds(100,75,20,20); txtSideC.setBounds(220,75,115,20);
        lblSelect.setBounds(130,100,70,20);
        btnCM.setBounds(210,100,30,20); 
        btnM.setBounds(245,100,30,20);
        btnKM.setBounds(280,100,30,20);
        lblAngles.setBounds(20,140,410,20);
        lblArea.setBounds(20,165,410,20);
        lblRightAngle.setBounds(20,190,410,20);
        
        // add the components to the frame
        add(lblInstructions);
        add(lblSideA);  add(txtSideA);
        add(lblSideB);  add(txtSideB);
        add(lblSideC);  add(txtSideC);
        add(lblSelect); add(btnCM); add(btnM); add(btnKM);
        add(lblAngles); add(lblArea); add(lblRightAngle);
    }
    
    private double[] getAngles(int a, int b, int c) {
        // create an array to store the 3 angles
        double[] angles = new double[3];
        double radians;

        // cast all the int values to double
        double dA=(double)a, dB=(double)b, dC=(double)c;
        
        // angle A in radians = cos^-1 (b^2 + c^2 - a^2 / 2bc)
        // and then convert the radians to degrees
        radians = Math.acos((dB*dB + dC*dC - dA*dA) / (2.0*dB*dC));
        angles[0] = radians * 180.0 / Math.PI;
        
        // angle B in radians = cos^-1 (a^2 + c^2 - b^2 / 2ac)
        // and then convert the radians to degrees
        radians = Math.acos((dA*dA + dC*dC - dB*dB) / (2.0*dA*dC));
        angles[1] = radians * 180.0 / Math.PI;
        
        // angle C in degrees = 180 - degrees A - degrees B
        angles[2] = 180.0 - angles[0] - angles[1];

        // return the 3 angles
        return angles;
    }

    private double getArea(int a, int b, int c) {
        // Heron's formula
        // s = (a + b + c)/2
        // area = sqrt( s(s - a)(s - b)(s - c) )
        double s = (a + b + c)/2.0;
        double area = Math.sqrt(s*(s-a)*(s-b)*(s-c));
        return area;
    }

    private boolean isRightTriangle(double[] angles) {
        for(int j = 0; j < angles.length; j++) {
            if(Math.abs(angles[j] - 90.0) < 0.05)
                return true;
        }
        return false;
    }
}