package ch5;
import javax.swing.JOptionPane;

public class Ch5
{

public void method1()
{ int a = 8; int b = 7;
if (b > a)
{     JOptionPane.showMessageDialog(null, "Surprise!");
}
else if (b == a)
{     JOptionPane.showMessageDialog(null, "Friday!");
}
else
{     JOptionPane.showMessageDialog(null, "Chocolate!");
}
}

public void method2()
{ int m = 11; int r = 6;
// how do you say "not equal to"
if (m != r)
    JOptionPane.showMessageDialog(null, "Tuesday!");
}

public void method3()
{ // to compare Strings or any objects
String name1 = "Bob", name2 = "Jane";
if (! name1.equals(name2))
    JOptionPane.showMessageDialog(null, "Saturday!");
else
    JOptionPane.showMessageDialog(null, "Sunday!");
}

public void method4()
{ double r = Math.sqrt(2);
double d = r * r - 2;

One approach:
if (d == 0)
    JOptionPane.showMessageDialog(null, "Equal");
else
    JOptionPane.showMessageDialog(null, "Not equal");
JOptionPane.showMessageDialog(null, "d = "+d);

A better approach for comparing doubles:
if (d < 1e-14)
    JOptionPane.showMessageDialog(null, "Equal");
else
    JOptionPane.showMessageDialog(null, "Not equal");
}

public static void main(String[] args)
{ Ch5 c = new Ch5();
//c.method1();
//c.method2();
//c.method3();
c.method4();
}
}