Adding Fly interface and modifying Eagle class and main

Eagle.java

@@ -1,4 +1,4 @@
-public class Eagle extends Bird {
+public class Eagle extends Bird implements Fly {
 
     private boolean flying;
     private int altitude;
@@ -21,4 +21,39 @@ public boolean isFlying() {
     public String sing() {
         return "Screech!";
     }
+
+    public void takeOff(){
+        if(!this.flying && altitude==0){
+            this.flying = true;
+            System.out.println(this.getName()+" takes off in the sky.");
+        }
+    }
+    public int ascend(int meters){
+        if(this.flying){
+            this.altitude = this.altitude + meters;
+            System.out.println(this.getName()+" flies upward, altitude: "+ this.altitude);
+        }
+        return this.altitude;
+    }
+    public void glide(){
+        if(this.flying) {
+            System.out.println("glides into the air.");
+        }
+    }
+    public int descend(int meters){
+        if(this.flying){
+            this.altitude = this.altitude - meters;
+            System.out.println(this.getName()+" flies downward,altitude "+this.altitude);
+        }
+        return this.altitude;
+    }
+    public void land(){
+        if(flying && this.altitude<=1){
+            System.out.println(this.getName()+" lands on the ground.");
+        }
+        else{
+            System.out.println(this.getName()+" is too high, it can't land!");
+        }
+
+    }
 }

Fly.java

@@ -0,0 +1,9 @@
+public interface Fly {
+
+    public void takeOff();
+    public int ascend(int meters);
+    public void glide();
+    public int descend(int meters);
+    public void land();
+
+}

Nature.java

@@ -13,7 +13,7 @@ public static void main(String[] args) {
 
         Eagle hawkeye = new Eagle("Hawkeye");
         // TODO : uncomment the following code in order to test it
-        /*
+
         hawkeye.takeOff();
         hawkeye.ascend(120);
         hawkeye.ascend(30);
@@ -22,6 +22,6 @@ public static void main(String[] args) {
         hawkeye.land();
         hawkeye.descend(9);
         hawkeye.land();
-        */
+
     }
 }

Swim.java

@@ -7,4 +7,6 @@ public interface Swim {
     int swimUp(int meters);
 
     void getOut();
+
+
 }