public class User {
    private String name; // 堆內(nèi)存中（對(duì)象成員）
    public void setName(String name) { // 棧內(nèi)存中（局部變量）
        this.name = name; // 明確將棧中name的值賦值給堆中name
    }
}

public class Order {
    public Order(String id, String product, int count, double price) {
        this.id = id;
        System.out.println("全參構(gòu)造初始化");
    }
    public Order(String id, String product, int count) {
        this(id, product, count, 0.0);
        System.out.println("省略price的構(gòu)造");
    }
    public Order(String id) {
        this(id, "未知商品", 1);
        System.out.println("僅id的構(gòu)造");
    }
}

public class UserBuilder {
    public UserBuilder setName(String name) {
        this.name = name;
        return this;
    }
    public User build() {
        return new User(name, age, email);
    }
}

public class Outer {
    public class Inner {
        public void show() {
            System.out.println(this.innerField); // 內(nèi)部類字段
            System.out.println(Outer.this.outerField); // 外部類字段
        }
    }
}
 

class Parent {
    String name = "Parent";
    public void print() {
        System.out.println("Parent print");
    }
}
class Child extends Parent {
    String name = "Child";
    @Override
    public void print() {
        System.out.println("Child print");
    }
    public void show() {
        System.out.println(name); // Child
        System.out.println(super.name); // Parent
        print(); // Child print
        super.print(); // Parent print
    }
}

class Grandparent {
    public Grandparent() {
        System.out.println("Grandparent");
    }
}
class Parent extends Grandparent {
    public Parent() {
        System.out.println("Parent");
    }
}
class Child extends Parent {
    public Child() {
        System.out.println("Child");
    }
}

class Animal {
    public void eat() {
        System.out.println("動(dòng)物進(jìn)食");
    }
}
class Dog extends Animal {
    @Override
    public void eat() {
        System.out.println("狗吃骨頭");
    }
    public void parentEat() {
        super.eat(); // 直接調(diào)用父類的eat
    }
}
public class Test {
    public static void main(String[] args) {
        Animal animal = new Dog(); // 向上轉(zhuǎn)型
        animal.eat(); // 動(dòng)態(tài)綁定：調(diào)用Dog的eat（輸出“狗吃骨頭”）
        Dog dog = new Dog();
        dog.parentEat(); // 調(diào)用Animal的eat（輸出“動(dòng)物進(jìn)食”）
    }
}

子類對(duì)象內(nèi)存布局：
[父類成員變量區(qū)][子類成員變量區(qū)][對(duì)象頭]
    ↑               ↑
  super指向        this指向（整個(gè)對(duì)象起始）

public class Test {
    public static void method() {
        // this.name; // 編譯錯(cuò)誤：static方法無this
        // super.method(); // 編譯錯(cuò)誤：static方法無super
    }
}

class Parent {
    public Parent() {
        init(); 
    }
    public void init() {
        System.out.println("Parent init");
    }
}
class Child extends Parent {
    private String name;
    @Override
    public void init() {
        System.out.println(name.length()); 
    }
    public static void main(String[] args) {
        new Child(); 
    }
}

public class Test {
    public Test() {
        // this(1); 與super()不能同時(shí)存在
        super(); 
    }
    public Test(int a) {}
}

abstract class AbstractProcessor {
    public final void process() {
        step1();
        step2(); 
        step3();
    }
    protected void step1() {
        System.out.println("固定步驟1");
    }
    protected abstract void step2(); 
    protected void step3() {
        System.out.println("固定步驟3");
    }
}
class ConcreteProcessor extends AbstractProcessor {
    @Override
    protected void step2() {
        System.out.println("子類實(shí)現(xiàn)的步驟2");
    }
    public static void main(String[] args) {
        AbstractProcessor processor = new ConcreteProcessor();
        processor.process(); 
    }
}

interface Component {
    void operation();
}
class ConcreteComponent implements Component {
    @Override
    public void operation() {
        System.out.println("基礎(chǔ)功能");
    }
}
abstract class Decorator implements Component {
    protected Component component;
    public Decorator(Component component) {
        this.component = component;
    }
}
class LogDecorator extends Decorator {
    public LogDecorator(Component component) {
        super(component);
    }
    @Override
    public void operation() {
        System.out.println("日志開始");
        component.operation(); 
        System.out.println("日志結(jié)束");
    }
}
class TimeDecorator extends Decorator {
    public TimeDecorator(Component component) {
        super(component);
    }
    @Override
    public void operation() {
        long start = System.currentTimeMillis();
        component.operation();
        System.out.println("耗時(shí)：" + (System.currentTimeMillis() - start));
    }
}
public class Test {
    public static void main(String[] args) {
        Component component = new TimeDecorator(
            new LogDecorator(new ConcreteComponent())
        );
        component.operation(); 
    }
}