Java高级 面向对象（封装 继承 多态 ）
第一点：
成员变量
    属性用成员变量去表示
    public  String name;
成员方法
    属性用成员变量去表示
    public void eat(){
    //输在控制台的语句
        System.out.println("L LOVE SEE you eat english");
    }
第二点：创建一个对象
People d = new People();
System.out.println(d.name);//获取成员变量name
d.eat();//获取成员方法d.eat();
第三点：创建对象
Student s1 = new Student();
s1.name="湖南";
s1.age = 30;
s1.study();
System.out.println(s1.name+","+s1.age);

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 面向对象编程思想，首先理解什么是对象 你要用对象干什么事情。利用对象思想去解决问题。

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package com.D1;
/*** 面向对象编程思想，首先理解什么是对象 你要用对象干什么事情。* @author MZFAITHDREAM**/public class Student {/*** 这个学生对象有什么属性* 名字 年龄*/String name;int age;//无惨构造public Student() {super();// TODO Auto-generated constructor stub}//有参构造public Student(String name, int age) {super();this.name = name;this.age = age;}//get and set 的方法/*** @return the name*/public String getName() {return name;}/*** @param name the name to set*/public void setName(String name) {this.name = name;}/*** @return the age*/public int getAge() {return age;}/*** @param age the age to set*/public void setAge(int age) {this.age = age;}public void study(){System.out.println("好好学习，天天向上");}public void doHomeWork(){System.out.println("键盘敲烂，月薪过万");}public void play(){System.out.println("玩玩游戏，人生百拜拜");}@Overridepublic String toString() {return "Student [name=" + name + ", age=" + age + "]";}}

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package com.D1;
/*** 学生测试类*/
public class StudentTest {public static void main(String[] args) {//创建对象名为studentStudent s = new Student();System.out.println(s);//使用对象成员变量System.out.println(s.name+","+s.age);System.out.println("调用方法用 对象中S.属性名 修饰成员变量");s.name = "我是student对象湖北";s.age = 28;//调用对象的方法System.out.println("调用方法用 对象中S.动作名(); 修饰成员方法");s.study();s.doHomeWork();s.play();System.out.println(s.name+","+s.age);//创建第二个对象Student s1 = new Student();s1.name="湖南";s1.age = 30;s1.study();System.out.println(s1.name+","+s1.age);//创建第三个对象Student s2 = new Student();s2.name="河北";s2.age = 30;System.out.println(s2.name+","+s2.age);System.out.println(s1==s2);//创建第四个对象Student s3 = new Student();s3.name="河南";s3.age = 20;System.out.println(s3.name+","+s3.age);System.out.println(s1==s3);}}

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package com.D2;public class Student {//成员变量private String name;private int age;public Student() {super();// TODO Auto-generated constructor stub}public Student(String name, int age) {super();this.name = name;this.age = age;}/*** @return the name*/public String getName() {return name;}/*** @param name the name to set*/public void setName(String name) {this.name = name;}/*** @return the age*/public int getAge() {return age;}/*** @param age the age to set*/public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Student [name=" + name + ", age=" + age + "]";}//	//定义一个设置姓名的方法
//	public void setName(String name1){
//		name = name1;
//	}
//	//定义一个获取姓名的方法
//	public String getName(){
//		return name;
//	}
//	//设置年龄
//	public void setAge(int age1){
//		if(age1>=0 && age1<=150){
//			age = age1;
//		}else{
//			System.out.println("年龄不合法");
//		}	
//	}
//	public int getAge(){
//		return age;
//	}}

package com.D2;
public class StudentTest {
/*** 代码test*//*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubStudent stu = new Student();//设置学生的姓名
//		stu.name = "maomao";stu.setName("兴旺里路mao mao mao");//获取学生的姓名System.out.println(stu.getName());//设置学生的年龄stu.setAge(17);System.out.println(stu.getAge());Student stu1 = new Student();stu1.setName("天行健，举哀天下名");System.out.println(stu1.getName());//设置学生的年龄stu1.setAge(34);System.out.println(stu1.getAge());Student stu2 = new Student();stu1.setName("生在盛世，当不服盛世");System.out.println(stu1.getName());//设置学生的年龄stu1.setAge(23);System.out.println(stu1.getAge());}}

 

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String 字符串的学习过程。

package String;public class Demo1 {public static void main(String[] args) {/** int length()返回字符串的长度*/String str1 = "我爱青年";int l = str1.length();System.out.println("字符长度为"+str1.length());/** char charAt(int index)返回字符串指定索引的字符* 注意：字符串中的第一个字符的索引为0*/String str2 = "abcde";char index = str2.charAt(4);System.out.println(index);/** String charAt(String str)将指定的字符串连接到该字符串的末尾 字符串的拼接*/String str3 = "加油！";String str4 = str3.concat("奥利给");System.out.println(str4);/** boolean endsWith(String str)测试此字符串是否以指定的后缀结尾。*/String str5 = "hello.java";boolean boo1 = str5.endsWith(".java");System.out.println(boo1);/** int indexOf(String str)返回指定子字符串第一次出现的字符串内的索引*/String str6 = "abcdefehcd";int index1 = str6.indexOf("cd");System.out.println(index1);/** int lastIndexOf(String str)返回指定子字符串最后一次出现的字符串内的索引*/String str7 = "abcdefehcd";int index2 = str7.lastIndexOf("cd");System.out.println(index2);/** String replace(char oldChar,char newChar)用新的字符将字符串的某些旧字符替换掉*/String str8 ="XXX,我真的想骂你";String str9 = str8.replace('X', '*');System.out.println(str9);/** String toLowerCase();将字符串中的所有大写字母转换为对应小写字母*/String str10 = "ABC你好y";String str11 = str10.toLowerCase();System.out.println(str11);/** String toUpperCase();将字符串中的所有小写字母转换为对应大写字母*/String str12 = "ABC你好y";String str13 = str12.toUpperCase();System.out.println(str13);/** String trim();去除字符串中首尾的空格*/String str14  = " 1 23 ";String str15 = str14.trim();System.out.println(str15);}}

package String;
/** 定义一个方法，把 int 数组中的数据按照指定的格式拼接成一个字符串返回，调用该方法， 并在控制台输出结果。* 例如，数组为 int[] arr = {1,2,3}; ，执行方法后的输出结果为：[1, 2, 3]*/
public class Demo2 {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubint[] arr={11,11,23,4,3678,245,34,3,67,89,345};//"[1,2,3]"//调用方法，返回拼接好的字符串String str = arrayToString(arr);System.out.println(str);}/*** 将一个数组转换为一个指令格式的字符串*/public static String arrayToString(int[] arr){//在方法中遍历数组，按照要求进行拼接String s = "";s += "[";//遍历数组for(int i=0;i<arr.length;++i){s=s+arr[i];if(i==arr.length-1){continue;}s=s+",";}s += "]";return s;}}

package String;
import java.util.Scanner;/*** 到过来* 定义一个方法，实现字符串反转。键盘录入一个字符串，调用该方法后，在控制台输出结果 * 例如，键盘录入 abc，输出结果 cba* 键盘录入 我爱你，输出结果 你爱我* @author Administrator**/
public class Demo3 {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubScanner scanner = new Scanner(System.in);System.out.println("请输入一个字符串");String str = scanner.next();String s = reverse(str);System.out.println(s);}/*** 利用reverse(名称)进行字符串的翻转* public static String reverse(String str)* 定义一个方法实现字符串的反转*/public static String reverse(String str){//定义一个字符串去作为返回的内容String s = "";//倒叙遍历str字符串中的字符for(int i=str.length()-1;i>=0;--i){s = s+str.charAt(i);}return s;}}

package String;
/*** * @author Administrator**/
public class Demo4 {/*** @param args*/public static void main(String[] args) {/** 计算运行时间*/// TODO Auto-generated method stubString s = "";long time1 = System.currentTimeMillis();System.out.println(time1);for(int i=0;i<100000;++i){s = s+"a";}long time2 = System.currentTimeMillis();System.out.println(time2-time1);}}

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package String;public class Demo5 {/*** @param args*/public static void main(String[] args) {// 创建一个36开白可变的字符串对象，不包含任何内容StringBuilder sb = new StringBuilder();System.out.println(sb);System.out.println(sb.length());//将一个字符串转换为可变内容的字符串StringBuilder sb1 = new StringBuilder("hello");System.out.println(sb1);System.out.println(sb1.length());}}

package String;
/*** StringBuilder append(String str)将指定的字符串附加到此字符序列* StringBuilder reverse()字符串的反转* @author Administrator**/
public class Demo6 {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubStringBuilder sb = new StringBuilder();StringBuilder sb2 = sb.append("hello");System.out.println(sb);System.out.println(sb==sb2);sb.append("	AAAAhellor");sb.append("BBBBworldr");sb.append("CCCCjavar");sb.append(100);//链式编程的定义sb.append("        hellor       ").append("worldr").append("javar").append(100);System.out.println(sb);//将字符串反转sb.reverse();System.out.println(sb);}}

package String;
/*** * @author Administrator**/
public class Demo7 {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubString s = "";StringBuilder  sb = new StringBuilder(s);//获取当前这一时刻long time1 = System.currentTimeMillis();System.out.println(time1);for(int i=0;i<100000;++i){sb.append("a");}long time2 = System.currentTimeMillis();System.out.println(time2-time1);s = sb.toString();}}

package String;
/** 定义一个方法，把 int 数组中的数据按照指定的格式拼接成一个字符串返回，调用该方法， 并在控制台输出结果。* 例如，数组为 int[] arr = {1,2,3}; ，执行方法后的输出结果为：[1, 2, 3]*/
public class Demo8 {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubint[] arr={145,2,3,34,89};//"[1,2,3]"//调用方法，返回拼接好的字符串String str = arrayToString(arr);System.out.println(str);}/*** 将一个数组转换为一个指令格式的字符串*/public static String arrayToString(int[] arr){//在方法中遍历数组，按照要求进行拼接
//		String s = "";StringBuilder s = new StringBuilder("");
//		s += "[";s.append("[");//遍历数组for(int i=0;i<arr.length;++i){s.append(arr[i]);if(i==arr.length-1){continue;}s.append(",");}s.append("]");return s.toString();}}

package String;
import java.util.Scanner;/*** 定义一个方法，实现字符串反转。键盘录入一个字符串，调用该方法后，在控制台输出结果 * 例如，键盘录入 abc，输出结果 cba* 键盘录入 我爱你，输出结果 你爱我* @author Administrator**/
public class Demo9 {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubScanner scanner = new Scanner(System.in);System.out.println("请输入一个字符串");String str = scanner.next();String s = reverse(str);System.out.println(s);}/*** 定义一个方法实现字符串的反转*/public static String reverse(String str){
//		//定义一个字符串去作为返回的内容
//		String s = "";
//		//倒叙遍历str字符串中的字符
//		for(int i=str.length()-1;i>=0;--i){
//			s = s+str.charAt(i);
//		}return new StringBuilder(str).reverse().toString();}}

package String;public class Snippet {public static void main(String[] args) {/** int length()返回字符串的长度*/String str1 = "我爱青年";int l = str1.length();System.out.println("字符串的长度为："+l);/** char charAt(int index)返回字符串指定索引的字符* 注意：字符串中的第一个字符的索引为0*/String str2 = "abcde";char index = str2.charAt(4);System.out.println(index);/** String charAt(String str)将指定的字符串连接到该字符串的末尾*/String str3 = "加油！";String str4 = str3.concat("奥利给");System.out.println(str4);/** boolean endsWith(String str)测试此字符串是否以指定的后缀结尾。*/String str5 = "hello.java";boolean boo1 = str5.endsWith(".java");System.out.println(boo1);/** int indexOf(String str)返回指定子字符串第一次出现的字符串内的索引*/String str6 = "abcdefehcd";int index1 = str6.indexOf("cd");System.out.println(index1);/** int lastIndexOf(String str)返回指定子字符串最后一次出现的字符串内的索引*/String str7 = "abcdefehcd";int index2 = str7.lastIndexOf("cd");System.out.println(index2);/** String replace(char oldChar,char newChar)用新的字符将字符串的某些旧字符替换掉*/String str8 ="XXX,我真的想骂你";String str9 = str8.replace('X', '*');System.out.println(str9);/** String toLowerCase();将字符串中的所有大写字母转换为对应小写字母*/String str10 = "ABC你好y";String str11 = str10.toLowerCase();System.out.println(str11);/** String toUpperCase();将字符串中的所有小写字母转换为对应大写字母*/String str12 = "ABC你好y";String str13 = str12.toUpperCase();System.out.println(str13);/** String trim();去除字符串中首尾的空格*/String str14  = " 1 23 ";String str15 = str14.trim();System.out.println(str15);}}

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Arraylist的集合

package arraylist;
import java.util.ArrayList;
import java.util.Iterator;
public class ArrayListDemo1 {
/*** 了解第一个集合ArrayList* @param args*/public static void main(String[] args) {// 1.创建一个集合ArrayList list  = new ArrayList();//2.给集合添加元素//创建学生对象Student stu0 = new Student("我是要删的数据",18);Student stu1 = new Student("狐疑",18);Student stu2 = new Student("糊涂",19);Student stu3 = new Student("呼啸",20);Student stu4 = new Student("环宇",21);list.add(stu0);list.add(stu1);list.add(stu2);list.add(stu3);list.add(stu4);list.hashCode();//3.删除集合中的指定元素 boolean remove(int index)list.remove(0);//4.获取集合中指定索引的元素 Object get(int index)System.out.println(list.get(0));//5.修改集合中指定元素的值 //public E  set(int index,E element)修改指定索引处的元素，返回被修改的元素list.set(2, new Student("maomao",21));//返回集合中元素的个数 int size()int count = list.size();System.out.println("集合中的元素个数为："+count);System.out.println("何为编程？");//遍历元素System.out.println("遍历元素第一种方式·");for (int i = 0; i < args.length; i++) {String string = args[i];System.out.println(i);}System.out.println(list);System.out.println("遍历第二种方式");for (Iterator iterator = list.iterator(); iterator.hasNext();) {Object object = (Object) iterator.next();System.out.println(list);System.out.println(list.size());}System.out.println("第三种方式");for (Object object : list) {System.out.println(list);}}}

package arraylist;
/***创建一个存储字符串的集合，存储3个字符串元素，使用程序实现在控制台遍历集合的所有元素*1.创建一个集合*2.往集合中添加3个字符串*3.遍历集合：首先要能获取到集合中的每一个元素，这个通过get(int index)方法去实现*4.遍历集合：其次要能够获取到集合中的长度，这个通过size()方法去实现** @author Administrator**/
import java.util.ArrayList;
import java.util.Iterator;
public class ArrayListDemo2 {/*** @param args*/public static void main(String[] args) {//1.创建一个集合ArrayList list = new ArrayList();//2.往集合中添加3个字符串list.add("诸葛亮");list.add("刘备");list.add("张飞");list.add("李四");list.add("我是list集合");//3-4遍历集合for(int i=0;i<list.size();++i){System.out.println(list.get(i));}System.out.println("方式一");for (int i = 0; i < list.size();i++) ;System.out.println(list);System.out.println("方式二");for (Iterator iterator = list.iterator(); iterator.hasNext();) {Object object = (Object) iterator.next();System.out.println(list);}}}

package arraylist;public class Student {private String name;private int age;public Student(String name, int age) {super();this.name = name;this.age = age;}public Student() {super();// TODO Auto-generated constructor stub}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;}@Overridepublic String toString() {// TODO Auto-generated method stubreturn "Student[age="+age+",name="+name+"]";}@Overridepublic int hashCode() {// TODO Auto-generated method stubreturn super.hashCode();}}

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案例接口。

 

package interfacea;/** 接口的定义与使用* 接口 定义 抽象*/
public interface USBA {
public void turnOn(); //设备启动'public void turnruning();  //设备运行public void turnOff();  //设备关闭public void name(); //设备名称public void color(); //设备颜色public void height();//设备高度public void weight();//设备宽度public void length(); //设备长度public void m();//设备的M方法}

package interfacea;public class aer  implements USBA{@Overridepublic void turnOn() {// TODO Auto-generated method stubSystem.out.println("are已启动，请开始以下程序");}@Overridepublic void turnruning() {// TODO Auto-generated method stubSystem.out.println("are开始运行自己设定的程序");}@Overridepublic void turnOff() {// TODO Auto-generated method stubSystem.out.println("手机结束自己运行的程序系统");}@Overridepublic void name() {// TODO Auto-generated method stubSystem.out.println("are名称为huaweiwww");}@Overridepublic void color() {// TODO Auto-generated method stubSystem.out.println("are色彩为back");}@Overridepublic void height() {// TODO Auto-generated method stubSystem.out.println("are高度为8cm");}@Overridepublic void weight() {// TODO Auto-generated method stubSystem.out.println("are宽度为15cm");}@Overridepublic void length() {// TODO Auto-generated method stubSystem.out.println("are长度为20cm");}@Overridepublic void m() {// TODO Auto-generated method stubSystem.out.println("m有飒飒");}}

package interfacea;public class ElectronicWhiteboard  implements USBA{@Overridepublic void turnOn() {// TODO Auto-generated method stubSystem.out.println("电子白板真在运行，打开你要的软件，并开始运行");}@Overridepublic void turnruning() {// TODO Auto-generated method stubSystem.out.println("电子白板真在运行，正在运行这个程序，并开始运行");}@Overridepublic void turnOff() {// TODO Auto-generated method stubSystem.out.println("电子白板结束自己运行的程序系统");}@Overridepublic void name() {// TODO Auto-generated method stubSystem.out.println("电子白板名称为huaweiwww");}@Overridepublic void color() {// TODO Auto-generated method stubSystem.out.println("电子白板色彩为back");}@Overridepublic void height() {// TODO Auto-generated method stubSystem.out.println("电子白板高度为150cm");}@Overridepublic void weight() {// TODO Auto-generated method stubSystem.out.println("电子白板宽度为200cm");}@Overridepublic void length() {// TODO Auto-generated method stubSystem.out.println("电子白板长度为300cm");}@Overridepublic void m() {// TODO Auto-generated method stubSystem.out.println("m有飒飒");}}

package interfacea;public class Mousea  implements USBA {@Overridepublic void turnOn() {// TODO Auto-generated method stubSystem.out.println("鼠标已启动，请开始以下程序");}@Overridepublic void turnruning() {// TODO Auto-generated method stubSystem.out.println("鼠标开始运行自己设定的程序");}@Overridepublic void turnOff() {// TODO Auto-generated method stubSystem.out.println("鼠标结束自己运行的程序系统");}@Overridepublic void name() {// TODO Auto-generated method stubSystem.out.println("鼠标名称为huaweiwwwe");}@Overridepublic void color() {// TODO Auto-generated method stubSystem.out.println("鼠标色彩为back");}@Overridepublic void height() {// TODO Auto-generated method stubSystem.out.println("鼠标高度为50mm");}@Overridepublic void weight() {// TODO Auto-generated method stubSystem.out.println("鼠标宽度为500mm");}@Overridepublic void length() {// TODO Auto-generated method stubSystem.out.println("鼠标长度为900mm");}@Overridepublic void m() {// TODO Auto-generated method stubSystem.out.println("m有飒飒");}}

package interfacea;public class Phonea  implements USBA{@Overridepublic void turnOn() {// TODO Auto-generated method stubSystem.out.println("手机已启动，请开始以下程序");}@Overridepublic void turnruning() {// TODO Auto-generated method stubSystem.out.println("手机开始运行自己设定的程序");}@Overridepublic void turnOff() {// TODO Auto-generated method stubSystem.out.println("手机结束自己运行的程序系统");}@Overridepublic void name() {// TODO Auto-generated method stubSystem.out.println("手机名称为huaweiwww");}@Overridepublic void color() {// TODO Auto-generated method stubSystem.out.println("手机色彩为back");}@Overridepublic void height() {// TODO Auto-generated method stubSystem.out.println("手机高度为8cm");}@Overridepublic void weight() {// TODO Auto-generated method stubSystem.out.println("手机宽度为15cm");}@Overridepublic void length() {// TODO Auto-generated method stubSystem.out.println("手机长度为20cm");}@Overridepublic void m() {// TODO Auto-generated method stubSystem.out.println("m有飒飒");}}

package interfacea;public class telephone implements USBA {@Overridepublic void turnOn() {// System.out.println("电话已启动，请打电话");}@Overridepublic void turnruning() {// TODO Auto-generated method stubSystem.out.println("电话开始进行联系对方");}@Overridepublic void turnOff() {// TODO Auto-generated method stubSystem.out.println("电话结束：请把电源turnoff");}@Overridepublic void name() {// TODO Auto-generated method stubSystem.out.println("电话名称为大哥大");}@Overridepublic void color() {// TODO Auto-generated method stubSystem.out.println("电话色彩为开门红");}@Overridepublic void height() {// TODO Auto-generated method stubSystem.out.println("电话高度为6cm");}@Overridepublic void weight() {// TODO Auto-generated method stubSystem.out.println("电话宽度为12cm");}@Overridepublic void length() {// TODO Auto-generated method stubSystem.out.println("电话长度为18cm");}@Overridepublic void m() {// TODO Auto-generated method stubSystem.out.println("MMMMMMMMMMMMMM");}}

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package interfacea;import java.util.ArrayList;public class DwmoTesta  {public static void main(String[] args) {ArrayList <USBA>usbs =new <USBA> ArrayList ();usbs.add(  new Mousea());    //类usbs.add(new Keyboarda());usbs.add(new Phonea());usbs.add(new ElectronicWhiteboard ());usbs.add(new telephone ());usbs.add(new aer());usbs.add(new HuBING());System.out.println("用for循化输出内容");for (int i = 0; i < usbs.size(); i++) {usbs.get(i).height();}System.out.println("height");for (int i = 0; i < usbs.size(); i++) {usbs.get(i).weight();}System.out.println("weight");for (int i = 0; i < usbs.size(); i++) {usbs.get(i).length();}System.out.println("设定设备的长：宽：高");	for (int i = 0; i < usbs.size(); i++) {usbs.get(i).turnOn();   //接口方法}System.out.println("设定程序启动的系统");System.out.println("============================");for (int i = 0; i < usbs.size(); i++) {usbs.get(i).turnOff();}System.out.println("设置程序正在运行的程序");System.out.println("============================");for (int i = 0; i < usbs.size(); i++) {usbs.get(i).turnruning();}System.out.println("设置程序名称");System.out.println("**********************");for (int i = 0; i < usbs.size(); i++) {usbs.get(i).name();}System.out.println("设置设备色彩为");System.out.println("**********************");for (int i = 0; i < usbs.size(); i++) {usbs.get(i).color();}for (int i = 0; i < usbs.size(); i++) {usbs.get(i).m();}	}}