Menghitung Luas dan Keliling Lingkaran Menggunakan Java
Lingkaran.java
public class Lingkaran
{
final double phi = 3.14;
double jari;
public void setJari(double jari0)
{
this.jari=jari0;
}
public double jari()
{
return(jari);
}
public double luas()
{
double luas0;
luas0=phi*jari*jari;
return(luas0);
}
public double keliling()
{
double keliling0;
keliling0=phi*diameter();
return(keliling0);
}
public double diameter()
{
double diameter0;
diameter0=jari*2;
return(diameter0);
}
public void tampil()
{
System.out.println("Jari-jari : "+jari);
System.out.println("Diameter  : "+diameter());
System.out.println("Luas  : "+luas());
System.out.println("Keliling  : "+keliling());

}

}

Main.java

public class Main
{
public static void main(String []args)
{
int i;
Lingkaran[] a;
a=new Lingkaran[5];

for(i=0;i<5;i++)
{
a[i]=new Lingkaran();
}
a[0].setJari(00.00);
a[1].setJari(10.00);
a[2].setJari(20.00);
a[3].setJari(30.00);
a[4].setJari(40.00);

for(i=0;i<5;i++)

if (a[i].diameter()<60){
System.out.println(" ");
System.out.println("==========================");
System.out.println("Lingkaran ke : "+i);
System.out.println("==========================");
a[i].tampil();

}
}

}