Interface in Java

interface.java

@@ -0,0 +1,60 @@
+import java.io.*;
+
+interface shape
+{
+
+ public void printArea();
+}
+class rectangle implements shape
+{
+  public void printArea() throws Exception
+   {
+     int l,b;
+     DataInputStream d=new DataInputStream(System.in);
+     System.out.println("enter the length");
+     l=Integer.parseInt(d.readLine());
+     System.out.println("enter the breadth");
+      b=Integer.parseInt(d.readLine());
+
+     System.out.println("AREA OF RECTANGLE="+(l*b));
+}
+}
+class triangle implements shape
+{
+   public void printArea() throws Exception
+   {
+     int l,b;
+     DataInputStream d=new DataInputStream(System.in);
+     System.out.println("enter the length");
+     l=Integer.parseInt(d.readLine());
+     System.out.println("enter the height");
+      b=Integer.parseInt(d.readLine());
+
+     System.out.println("AREA OF TRIANGLE="+(0.5f*l*b));
+}
+}
+class circle implements shape
+{
+   public void printArea() throws Exception
+   {
+      int l,b;
+     DataInputStream d=new DataInputStream(System.in);
+     System.out.println("enter the radius");
+     l=Integer.parseInt(d.readLine());
+
+
+     System.out.println("AREA OF CIRCLE="+(3.14f*l*l));
+}
+}
+class m
+{
+ public static void main(String v[]) throws Exception
+{
+  rectangle r=new rectangle();
+  r.printArea();
+  triangle t=new triangle();
+  t.printArea();
+  circle c=new circle();
+  c.printArea();  
+}
+}