JavaSE9作业和JavaSE10代码

JavaSE10/JavaSE10.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

JavaSE10/src/demo1/Alpha.java

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+package demo1;
+
+class Base {
+    Base() {
+        System.out.print("Base");
+    }
+}
+
+public class Alpha extends Base {
+
+    public static void main( String[] args ) {
+        new Alpha();//1
+        //调用父类无参的构造方法
+        new Base();//2
+    }
+}

JavaSE10/src/demo2/Derived.java

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+package demo2;
+
+class Base{
+    public Base(){
+        System.out.print("B");
+    }
+}
+
+public class Derived extends Base{
+    public Derived (String s) {
+        super();
+        System.out.print("D");
+    }
+    public static void main(String[] args){
+        new Derived("C");
+    }
+}

JavaSE10/src/demo3/Z.java

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+package demo3;
+
+class X{
+    Y y=new Y();//1
+    public X(){//2
+        System.out.print("X");
+    }
+}
+class Y{
+    public Y(){//3
+        System.out.print("Y");
+    }
+}
+public class Z extends X{
+    Y y=new Y();//4
+    public Z(){//5
+        System.out.print("Z");
+    }
+    public static void main(String[] args) {
+        new Z();
+    }
+}

JavaSE10/src/多态/Test.java

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+package 多态;
+
+class Animal{
+    private String name;
+    private int age;
+
+    public Animal(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public void  eat(){
+        System.out.println(name + "正在吃饭");
+    }
+
+    @Override
+    public String toString() {
+        return "Animal{" +
+                "name='" + name + '\'' +
+                ", age=" + age +
+                '}';
+    }
+}
+class Dog extends Animal{
+
+    public Dog(String name, int age) {
+        super(name, age);
+    }
+    public void bark(){
+        System.out.println(getName()+"汪汪汪！");
+    }
+}
+class Bird extends Animal{
+    public String wing;
+    public Bird(String name, int age) {
+        super(name, age);
+    }
+    public void fly(){
+        System.out.println(getName()+"正在飞");
+    }
+    public void eat(){
+        System.out.println(getName()+"要吃鸟粮");
+    }
+}
+
+public class Test {
+    public static void main(String[] args) {
+        /*Bird bird = new Bird("鹦鹉", 2);
+        Animal animal = bird;*/
+        //上下两段相等
+        Animal animal = new Bird("鹦鹉", 2);//向上转型
+        /*animal.fly();*///只能引用Animal里面的方法
+        /*animal.wing;*///只能调用自己特有的方法，不可以调用子类的方法
+        animal.eat();//动态绑定
+    }
+
+    public static void main1(String[] args) {
+        Bird bird = new Bird("鹦鹉",2);
+        bird.fly();
+        bird.eat();
+
+    }
+}