case1: 创建一个person类，其中拥有两个子类，分别是Name类和Sex类。

//定义一个Name类
class Name {
      //定义两个私有变量firstname,lastname,保证变量的安全性
      private String firstname;
      private String lastname;
      //定义两个Name类，分别是不带参数的和带参数的
      public Name() { }
      public Name(String firstname,String lastname) {
                this.firstname = firstname;
                this.lastname = lastname;
      }
      //定义两个变量的setter和getter方法
      public void set.firstname(String firstname) {
                this.firstname = firstname;
      }
      public void set.lastname(String lastname) { 
                this.lastname = lastname;
      }
      public void getfirstname(String firstname) {
                return firstname;
      }
      public void getlastname(String lastname) {
                return lastname;
      }
}

再定义一个Sex类
class Sex {
      private String sex1;
      private String sex2;
      public Sex() { }
      public Sex(String sex1,String sex2) {
              this.sex1 = sex1;
              this.sex2 = sex2;
      }
      //定义两个变量的setter和getter方法
      public void set.sex1(String sex1) {
                this.sex1 = sex1;
      }
      public void set.sex2(String sex2) {
                this.sex2 = sex2;
      }
      public void get.sex1(String sex1) {
                return sex1;
      }
      public void get.sex2(String sex2) {
                return sex2;
      }

//最后，定义一个Person类作为一个实例
public class Person {
      private Name name;
      private Sex sex;
      public Person(Name name) {
                this.name = name;
      }
      public Name getName() {
                return name;
      }
      public Person(Sex sex) {
                this.sex = sex;
      }
      public Sex getSex() {
                return sex;
      }
      public static void main(String[] args) {
                  Name n = new Name("Bryant","Kobe");
                  Sex s = new Sex("man","woman");
                  Person p = new Person(n);
                  Person x = new Person(s);
                  System.out.println(p.getName().getfirstname()+p.getName().getlastname());
                  System.out.println(p.getSex().getSex1()+p.getSex().getSex2());
        }
}

输出结果为：
KobeBryant
manwoman
至此此案例也实现成功，其中sex是我在借鉴name类的基础上添加的，也可以因此引申出其他多个类；

class2: HashMap的使用

import java.util.HashMap;

public class HelloHashMap {
        public static void main(String[] args) {
                int[] inputInt = {1,2,3,4,4,3,5,7,2,8,1};
                char[] inputChar = {'a','b','d','g','d','a','b','c'}; 
                System.out.println(testInteger(inputInt));
                System.out.println(testChar(inputChar));
        }

        private static HashMap<Integer,Integer> testInteger(int[] array) {
                HashMap<Integer,Integer> result = new HashMap<>();
                Integer current;
                for(int i = 0; i < array.length; i++) {
                        int num = array[i];
                        if(!result.containsKey(num)) {
                                current = 0;
                        } else {
                                 current = result.get(num);
                        }
                        current++;
                        result.put(num,current);
                }
                return result;
        }

        private static HashMap<Character,Integer> testChar(char[] array) {
                HashMap<Character,Integer> result = new HashMap<>();
                Integer current;
                for(int i = 0; i < array.length; i++) {
                         char num = array[i];
                          if(!result.containsKey(num)) {
                                  current = 0;
                          } else {
                                  current = result.get(num);
                          }
                          current++;
                          result.put(num,current);
                }
                return result;
        }
}

线程的两种方法

package study;

/**
 * Created by s on 2017/6/10.
 * 单继承类
 */
public class ThreadTest extends Thread {
    public void run() {
        for(int i= 0; i < 10;i++) {
            try{
                Thread.sleep(100);
            }catch(InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("MyThread" + i);
        }
    }
}