import java.util.LinkedList;

public class ListTest {

    public static void main(String [] args){

        //ArrayList<String> list = new ArrayList<>();
        LinkedList<String> list = new LinkedList<>();

        //往容器里面添加对象
        list.add("jack");
        list.add("tom");
        list.add("marry");

       String lastObj =  list.getLast();
        //System.out.println(list);
       // System.out.println(list.get(0));

        //更新一个元素
        list.set(0,"小D");
        System.out.println(list);

        //返回大小
       int size =  list.size();
        System.out.println("size="+size);

        //根据索引删除一个元素
       String indexRemove =  list.remove(1);
        System.out.println("删除后的元素："+list);

        //根据对象删除元素
        boolean flag = list.remove("jack");



        //是否为空
       boolean beforeClear =  list.isEmpty();

       System.out.println("clear 之前 isEmpty = "+ beforeClear);

        list.clear();
        //清空元素
       boolean afterClear = list.isEmpty();


       System.out.println("clear 之后 isEmpty = "+ afterClear);


    }
}

//重点：
//LinkedList特有api
//获取第⼀一个元素
list.getFirst();
//获取最后⼀一个元素
list.getLast();

interface ICompute{
    int computer(int num1, int num2);
}
public class AddOper implements ICompute {
    @Override
    public int computer(int num1, int num2) {
        return num1 + num2;
    }
}
public class SubOper implements ICompute {
    @Override
    public int computer(int num1, int num2) {
        return num1 - num2;
    }
}
public class MulOper implements ICompute {
    @Override
    public int computer(int num1, int num2) {
        return num1*num2;
    }
}
public class DivideOper implements ICompute {
    @Override
    public int computer(int num1, int num2) {
        try {
            return num1/num2;
        }catch (Exception e){
            e.printStackTrace();
        }
        return -1;
    }
}
public class UseCompute {
    public static void compute(ICompute compute, int num1, int num2){
        int result = compute.computer(num1,num2);
        System.out.println(result);
    }
//    public static void add(AddOper compute, int num1, int num2){
//
//        int result = compute.computer(num1,num2);
//        System.out.println(result);
//    }
//
//    public static void sub(SubOper compute, int num1, int num2){
//
//        int result = compute.computer(num1,num2);
//        System.out.println(result);
//    }
    public static void main(String [] args){
        UseCompute.compute(new AddOper(),25,5);
        UseCompute.compute(new SubOper(),25,5);
        UseCompute.compute(new MulOper(),25,5);
        UseCompute.compute(new DivideOper(),25,0);
    }

public final class Doubleextends Numberimplements Comparable<Double>

public final class Mathextends Object

public class Father {
    static {
        System.out.println("父类静态代码块");
    }
    public Father(){
        System.out.println("father 无参构造函数");
    }
    public Father(int age){
        System.out.println("father 有参构造函数");
    }
    public void sleep(){
        System.out.println("father sleep方法");
    }
}
public class Children extends Father{
    static {
        System.out.println("Child静态代码块");
    }
    public Children(){
        //super();
        System.out.println("Child⽆参构造函数");
        super.sleep();
    }
    public void sleep(){
        System.out.println("Child sleep方法");
    }
}
public static void main(String[] args) {
        new Children().sleep();
 }

public class AnswerTest {

    public static void main(String [] args){
       // test1();

        //test2();
        test3();
    }

    public static void test3(){
        Dog [] dogs = new Dog[5];

        for(int i=0; i<5; i++){
            Dog dog = new Dog();
            dog.setName("旺财"+i);
            dogs[i] = dog;
        }

        Dog dog =  dogs[3];
        dog.changeAge();
        dog.changeAge();

        for (Dog d : dogs){
            System.out.println("名称="+d.getName() + ", age="+d.getAge());
        }


    }

    public static void test2(){
        int season = 10;

        String content;

        switch (season){
            case 1:content="春";
                break;

            case 2:content="夏";
                break;

            case 3:content="秋";
                break;

            case 4:content="冬";
                break;

            default: {
                content="错误季节";
                System.out.println("default 执行");
            }
        }

        System.out.println(content);

    }

    public static void test1(){
        Student[] arr1 = new Student[60];
        int arr1Index = 0;

        Student[] arr2 = new Student[40];
        int arr2Index = 0;

        for(int i=0; i<100; i++){
            int num = i+1;
            Student student = new Student();
            student.setId(num);
            if(num > 60){
                arr2[arr2Index] = student;
                //arr2Index = arr2Index +1;
                arr2Index++;
            }else {
                arr1[arr1Index] = student;
                arr1Index++;
            }
        }


        for(Student s: arr1){
            System.out.println(s.getId());
        }

        System.out.println("============");
        for(Student s: arr2){
            System.out.println(s.getId());
        }

    }
}
public class Student {

    private int id;

    public int  getId(){
        return id;
    }

    public void setId(int id){
        this.id = id;
    }
}

public class Dog {

    public static int age =10;

    private String name;

    public void setName(String name){
        this.name = name;
    }

    public String getName(){
        return name;
    }

    public void changeAge(){
        age++;
    }

    public int getAge(){
        return age;
    }

}