public class HelloWorld { public static void main(String[] args) { Dog animal1 = new Dog(); Cat animal2 = new Cat(); Duck animal3 = new Duck(); animal1.sayHello(); animal2.sayHello(); animal3.sayHello(); } }
class Dog { public void sayHello() { System.out. } }
class Cat { public void sayHello() { System.out.println("Meow"); } }
class Duck { public void sayHello() { System.out.println("Quack"); } }
public class HelloWorld { public static void main(String[] args) { Dog animal1 = new Dog(); Cat animal2 = new Cat(); Duck animal3 = new Duck(); System.out.println("A dog says " +animal1.getHello() +", is carnivorous: " +animal1.isCarnivorous() +", is a mammal: " +animal1.isAMammal());
System.out.println("A cat says " +animal2.getHello() +", is carnivorous: " +animal2.isCarnivorous() +", is a mammal: " +animal2.isAMammal());
System.out.println("A duck says " +animal3.getHello() +", is carnivorous: " +animal3.isCarnivorous() +", is a mammal: " +animal3.isAMammal()); } }
abstract class Animal { public boolean isAMammal() { return(true); }
public boolean isCarnivorous() { return(true); }
abstract public String getHello(); }
class Dog extends Animal { public String getHello() { return("Bark"); } }
class Cat extends Animal { public String getHello() { return("Meow"); } }
class Duck extends Animal { public boolean isAMammal() { return(false); }
public boolean isCarnivorous() { return(false); }
public String getHello() { return("Quack"); } }
在編譯并運行我們的程序以后,輸出應該如下: A dog says Bark, is carnivorous: true, is a mammal: true A cat says Meow, is carnivorous: true, is a mammal: true A duck says Quack, is carnivorous: false, is a mammal: false
