移动打车项目1

// 只能用一个类名和文件名一致
// 模块export andri
//定义一个类在外界调用
public class HelloJava
{ // 主方法
public static void main(String args[])
{
System.out.printIn("Hello java")
}

}

return shell 开启一个线程执行a.out return 的返回值返回给shell

calss Dog
{
Dog(){
this.color = "black"
}
Dog(String color){

this.color = color
}
public void sleep(){
System.out.println(this.color + "Dog is sleep");
}
private String color;
}

public class Text2_demo
{
public static void main(String args[]){

Dog dog1 = new Dog();
Dog dog2 = new Dog("dahuang");
dog1.sleep();
}

}

值传递 c/c++ 值传递开辟新空间
java python 基本类型传递的都是值传递，复杂类型引用

byte,long double ,boolean, char , 解释方式不同
应用类型： new 出来的都是引用

class test3{
// 共用的静态常量类型
public static final String content = "AC"

}

public class Text3
{
public static void main(String args[]){
  System.out.println(test3.content);
  test3 t = new test3();
  System.out.println(t.content);
  t.content = "123";
  System.out.println(t.content);
}

}

public class Test4_static{

private int a = 0;
public static void main(String args[]){

}
}

c/c++ : 类中的声明变量
java: 中可以声明定义

静态方法没有this指针;

default: 在当前文件可用
final 常量
对有符号的不能左移。
instanof
公共类

class Hero{
public void attack(){
System.out.println("attack");

}

继承
class Yase extends Hero{
// 方法重写
public void attack(){
System.out.println("")

}
}
public class Test_externts()
{
     public static doAttack(Hero hero){
     if (hero instanceof Yase){
       System.out.println("yes");

     }esle if(hero instanceof Libai)
     {
       System.out.println("LIBAI");
     }
     hero.attack();// 多态

}

public static void main(String args[]){
Hero hero = new Hero();

hero.attack();

     Hero y = new Yase();
     y.attack();
     Hero l = new LiBai();
     l.attack();

}

静态方法：类方法

public class Test_Array{

public static void printArray(int[] array){
  for(int item: array){
   System.out.println(item);
  }

}
// 二维数组
public static void printArray2(int..arry)
{
  for(int i; i< array.length;i++)
  {
   System.out.println(array[i])
  }

}

public static void main(String args[]){
int[] array1 = {1,2,3,4,5};// 定义一个数组
int[] array2 = new int[5]; // 引用

}
}
数组名值常指针

组合方式：
class Son1
{
Son1(Fathor fa)
{
this->fa = fa;
}
private:
Fathor *fa;
}
继承方式：
class Son: public Fathor
{

}

导入包
import java.util.Date;
public class Test_date{
public static void main(String args){
  Date date = new Date();
  System.out.println(date.toString());
}

}

时间：系统时间
localtime: 本地时间
格式化时间：

import java.util.*
public class Test7{
  public static void main(String args[]){
   try{
    System.out.println(new Date()+"\n");
    Thread.sleep(1000*3);
    System.out.println(new Date()+"\n");

   }catch(Exception e){
    System.out.println("Gat an exception");
   }
  }
}
-----------------------------------------------
// 默认继承 object
class Hero{

Hero(String name){
  this.name = name;
}
// 不能修改权限
protected void finalize(){

}
private String name;
}
// 不定时回收
public class Test7{

public static void main(String args[]){
Hero h = new Hero("Gailun");
// 显示调用回收
h = null;
//手动执行
System.gc();

}
}

-------------------------------

public class Test7{

  public static void main(String args[]){
   char[] strArray = {"A","B","C"};
   String str1 = new String(strArray);
   String str2 = new String("abc");
   String str3 = "xye";
   String str4;
   str4 = String.format("%f,%d,%s",3.14,100,"itcast")
   System.out.println(str4);

}
}

----------------------------
import java.io.*

public class Test{

  public static void main(String[] args){
   byte[] binary = {1,2,3,4,5};
   // 输出流文件流进程往外流
   try{
    OutputStream os =new FileOutputStream("test.txt");

   for(int i=0;i<binary.length; i++){
    os.write(binary[i]);
   }
   os.close();

   InputStream is = new FileInputStream("test.txt");
   int size = is.available();
   for(int i=0;i< size;i++){
    System.out.print(is.read()+",");
   }
   is.close();
   }catch(IOException e){

   System.out.println("io error");
   }

  }
}

hexdump: 查看二进制文件表示方式
00000000(地址) 0201 0403 0005
00000005 (地址)
-------------------------------------
抽象类

class Animal{
public void move(){
System.out.print("")
}
}
class Dog extends Animal{

public void move(){
  super()
  super.move(); // 第一个父类
  System.out.print()
}
}
主方法
public class TestDog{
public static void main(String[] args){

}
}

有虚函数
abstract class Animal{
abstract void eat();
String name; //属性
}

class Dog extends Animal{
Dog(String name){
this.name = name;
}
System.out.print(this.name + "sleep");

}
class Test{
public static void show(Animal animal){
  animal.eat();
  if(animal instanceof Dog){
   Dog d = (Dog)animal;
   d.eat();
  }else if(animal instanceof Cat){
   Cat c = (Cat)animal;
   c.eat();
  }
}
public static void main(String []args){
  Animal cat = new Cat("Tom");
  Animal dog = new Dog("Big");
  show(cat);
  show(dog);
}
}

---------------------------

interface Fight{
public void attack();
public void skill();

}

interface Action{
public void run();
public void die();
}

abstract Hero{
Hero(Sting name){
this.name = name;
}
public abstrack void kill();
private String name;
}

class Gailun extends Hero implement Fight,Action{
Gailun(){
super("gailun");
}
// 实现接口
public void attack(){}
public void skill(){}
public void run(){}
public void die(){}
// 实现抽象方法
public void kill(){

  this.run();
  this.attack();
  this.skill();

}

---------------------
mkdir Animals
Animal.java
package animals; //当前模块
接口
public interface Animal{
public void eat();
public void sleep();
}
--------------------
vsp Cat.java

package animals;
public class Cat implements Animal{
public void eat()
{
System.out.print("hhh");
}
}

wq:

一个包：一个抽象类，两个实体类

-----------------------
import animals.Animal;
import animals.cat
import animals.Dog

public class Test{
public static void main(String args[]){
  Animal dog = new Dog();
  Animal Cat = new Cat();

}
}

posted @ 2019-09-23 07:23 countryboy666 阅读(336) 评论(0) 编辑收藏举报

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移动打车项目1

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