ljy练习题.docx

1、ljy练习题1对象,有,可以有,不可以有_键值对映关系,值value,键值key2.1.for (int i=0;ilist.size();i+) System.out.println(list.get(i);2. 程序运行结果:Hello World Learn Java3.Hello Learn4.C5 1) public void work() System.out.println(getName() + work); Override public boolean equals(Object obj) Worker user = (Worker)obj; Worker user1 =

2、new Worker(); user1 = (Worker)obj; if(obj!=null) return this.name.equals(user1.name) & this.age=(user1.getAge(); return true; Override public int hashCode() int result = 0; if (name != null) result = name.hashCode(); return result + age; / TODO Auto-generated method stub package user;import java.uti

3、l.ArrayList;import java.util.HashSet;import java.util.Iterator;import java.util.List;public class dad public static void main(String args) Worker u = new Worker(); u.setAge(18); u.setName(zhang3); u.setSalary(3000); Worker u2 = new Worker(); u2.setAge(25); u2.setName(li4); u2.setSalary(3500); Worker

4、 t2 = new Worker(); t2.setAge(22); t2.setName(wang5); t2.setSalary(3200);/* * /*1) 创建一个List，在List * 中增加三个工人，基本信息如下： 姓名 年龄 * 工资Salary zhang3 18 3000 li4 * 25 3500 wang5 22 3200 */ int ty = 0; int ty1 = 0; List list = new ArrayList(); list.add(u); list.add(u2); list.add(t2); for (int i = 0; i list.siz

5、e(); i+) System.out.print(list.get(i); System.out.println(=); for (int i2 = 0; i2 list.size(); i2+) String sa = list.get(i2).toString(); if (sa.equals(u2.toString() System.out.println(i2); ty = i2; Worker t3 = new Worker(); t3.setAge(24); t3.setName(zhao6); t3.setSalary(3200); Worker uu=new Worker()

6、; list.add(ty, t3);/在li4 之前插入一个工人，信息为：姓名：zhao6，年龄：24，工资3300 System.out.println(=); for (int i = 0; i list.size(); i+) System.out.println(list.get(i);/利用for 循环遍历，打印List 中所有工人的信息 list.remove(t2);/ 删除wang5 的信息 System.out.println(=); for (int i = 0; i list.size(); i+) System.out.println(list.get(i);/利用f

7、or 循环遍历，打印List 中所有工人的信息 System.out.println(=); for (int i2 = 0; i2 list.size(); i2+) String sa = list.get(i2).toString(); if (sa.equals(u2.toString() System.out.println(i2); u2.work(); if (sa.equals(u.toString() System.out.println(i2); u.work(); if (sa.equals(t2.toString() System.out.println(i2); t2

8、.work(); if (sa.equals(t3.toString() System.out.println(i2); t3.work(); Worker t4 = new Worker(); t4.setAge(24); t4.setName(zhao6); t4.setSalary(3200); HashSet s =new HashSet(); s.add(t4); s.add(t3); s.add(t2); System.out.println(=); Iterator it = s.iterator(); / 判断当前的迭代器是否还存在元素， while(it.hasNext()

9、/打印元素 System.out.println(it.next(); System.out.println(=); 6C7import java.util.*;class WorkerString name;int age;double salary;public Worker()public Worker(String name, int age, double salary)this.name = name;this.age = age;this.salary = salary;Public int hashCode()return name.hashCode() + age + (in

10、t)salary;public boolean equals(Worker w)w=(Worker )obj;if (w.name = name & w.salary = salary & w.age = age)return true;else return false;public class TestWorkerpublic static void main(String args)Set set = new HashSet();set.add(new Worker(“tom”, 18, 2000);set.add(new Worker(“tom”, 18, 2000);set.add(

11、0, new Worker(“jerry”, 18, 2000); /不正确 hashset 的add方法木有在第几位添加制定数据的方法,故删除”0,”System.out.println(set.size();8.int result = 0; if (name != null) result = name.hashCode(); return result + age;将hashcode方法改写为以上即可.9public int compareTo(Object o) Worker user = (Worker) o;int res = user.age b) return 1; else

12、 if (a = b) int rdd = pareTo(user.name);/ 为什么更换变量之后会改变自然排列顺序,先初始变量,再后来变量 return rdd; else return -1; return res; 10.1替换原映射,2新建映射,3只能移除key值,4返回指定键所映射的值；5如果此映射不包含该键的映射关系，则返回 null。 6指定key值,7返回指定键所映射的值,8keySet() 9.返回此映射中包含的键的 Set 视图, 10.values() 11.返回此映射中包含的值的 Collection 视图。12.entrySet()方法,13.返回此映射中包含的映

13、射关系的 Set 视图。11import java.util.HashMap;import java.util.Map;public class x public static void main(String args) Map jjj1=new HashMap(); jjj1.put(1990, xide); jjj1.put(1994, baxi); jjj1.put(1998, faguo); System.out.println(第一次测试); String year=2005; System.out.println(输入变量为year,+year); if(jjj1.contain

14、sKey(year)=true)System.out.println(jjj1.get(year);else System.out.println(没有举办世界杯。); System.out.println(第二次测试); year=1998; System.out.println(输入变量为year,+year); if(jjj1.containsKey(year)=true)System.out.println(jjj1.get(year);else System.out.println(没有举办世界杯。);12import java.util.HashMap;import java.ut

15、il.Iterator;import java.util.Map;import java.util.Map.Entry;public class x public static void main(String args) System.out.println(=); System.out.println(第一次测试课程安排); Map jjj1=new HashMap () ; jjj1.put(老师, 课程); jjj1.put(Tom, CoreJava); jjj1.put(John, Oracle); jjj1.put(Susan, Oracle); jjj1.put(Jerry,

16、JDBC); jjj1.put(Jim, Unix); jjj1.put(kevin, JSP); jjj1.put(Lucy, JSP); System.out.println(jjj1.entrySet(); System.out.println(=); System.out.println(第2次测试增加一个老师Allen 教JDBC); jjj1.put(Allen, JDBC); System.out.print(jjj1.entrySet(); System.out.println(=); System.out.println(第3次测试增加Lucy 改为教CoreJava); j

17、jj1.put(Lucy, CoreJava); System.out.print(jjj1.entrySet(); System.out.println(=); System.out.println(第4次测试遍历Map，输出所有的老师及老师教授的课程); System.out.print(jjj1.entrySet(); System.out.println(=); System.out.println(第5次测试利用Map，输出所有教JSP 的老师。);15 10 50 3016A17package user;public class Addrress String adrressnam

18、e; String zipCode; Override public String toString() return adrressname= + adrressname+ , zipCode= + zipCode+ ; public String getAdrressname() return adrressname;public void setAdrressname(String adrressname) this.adrressname = adrressname;public String getZipCode() return zipCode;public void setZip

19、Code(String zipCode) this.zipCode = zipCode;package user;import java.util.*;public class Worker private int age; private String name; private double salary; private String adress; Addrress adrress =new Addrress(); Override public String toString() return name +age= + age+ , name= + name+ , salary= +

20、 salary +, adrress+adrress+ ; public Worker () public Worker (String name, int age, double salary,Addrress adrress) this.name = name; this.age = age; this.salary = salary; this.adrress=adrress; public int getAge() return age; public void setAge(int age) this.age = age; public String getName() return

21、 name; public void setName(String name) this.name = name; public double getSalary() return salary; public void setSalary(double salary) this.salary = salary; public void work() System.out.println(getName() + work); Override public boolean equals(Object obj) Worker user1 = new Worker(); user1 = (Work

22、er)obj; if(obj!=null) / 第二步进行比较 属性值是否相等 return this.name.equals(user1.name) & this.age=(user1.getAge(); return true; Override public int hashCode() int result = 0; if (name != null) result = name.hashCode(); return result + age; / TODO Auto-generated method stub /return super.hashCode(); 18package u

23、ser;import java.util.HashMap;import java.util.Map;public class football public static void main(String args) Map jjj1=new HashMap(); jjj1.put(1990, xide); jjj1.put(1994, baxi); jjj1.put(2002, faguo); jjj1.put(1998, faguo); jjj1.put(2006, faguo); jjj1.put(2010, faguo); System.out.println(第一次测试); Stri

24、ng year=2005; System.out.println(输入变量为year,+year); if(jjj1.containsKey(year)=true)System.out.println(jjj1.get(year);else System.out.println(没有举办世界杯。); System.out.println(第二次测试); year=1998; System.out.println(输入变量为year,+year); System.out.println(jjj1.get(henan);/荷兰还没夺过冠. if(jjj1.containsKey(year)=tru

25、e)System.out.println(jjj1.get(year);else System.out.println(没有举办世界杯。); String qiudui=henan; if(jjj1.containsValue(qiudui)=true)System.out.println(qiudui+夺过冠);else System.out.println(qiudui+未夺过世界杯。);19package user;import java.util.*;public class TestAccout public static void main(String args) List li

26、st = new ArrayList(); list.add(new Account(10.00, 1234); list.add(new Account(15.00, 5678); list.add(new Account(0, 1010); Map jjj=new HashMap(); Account aa=new Account(); List list1=new ArrayList(); for(int i=0;ilist.size();i+)aa.setID(i);list1.add(aa.getID(); jjj.put(list1, list); System.out.println(jjj.entrySet(); package user;public class Account long ID; double balance; String password; Account() Account(double balance,String password) this.balance=balance;this.password=password; public long getID() return ID; public voi