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1，我们先来讲讲什么是泛型化编程
package 学生管理系统;
import java.util.ArrayList;
import java.util.List;
/*
* 进行泛型化编程
* @autor：pcb
* */
public class TestGeneric {
//进行泛型化编程，规定类型。
public List <CourseClass> courses;
public TestGeneric() {
this.courses = new ArrayList<CourseClass>();
}
public void testAdd() {
CourseClass cr1 = new CourseClass("1","大学语文");
courses.add(cr1);
//泛型集合中不能添加规定意外的对象
//courses.add("能否添加一些奇怪的东西");
CourseClass cr2 = new CourseClass("2","Java基础");
courses.add(cr2);
}
public void testForEach() {
//进行泛型之后，可直接利用它规定的类型及其子类型直接进行访问
for(CourseClass cr:courses) {
System.out.println(cr.id+":"+cr.name);
}
}
//泛型集合可以添加泛型的子类型的对象实例
public void testChild() {
ChildCourse ccr = new ChildCourse();
ccr.id = "3";
ccr.name = "我是子类的课程实例对象";
courses.add(ccr);
}
//泛型必须使用包装类型进行创建,例如：int和integer
public void testBaic() {
List<Integer> list = new ArrayList<Integer>();
list.add(1);
System.out.println("基本类型必须使用包装类作为泛型！"+list.get(0));
}
public static void main(String[] args) {
TestGeneric tg = new TestGeneric();
tg.testAdd();
tg.testForEach();
tg.testChild();
tg.testForEach();
tg.testBaic();
//tg.testForEach();
}
}
2.我们开始进行管理系统的创建，创建一个学生类和一个课程类
package 学生管理系统;
import java.util.HashSet;
import java.util.Set;
public class StudentsClass implements Comparable <StudentsClass> {
public String id;
public String name;
public Set<CourseClass> courses;
public StudentsClass(String id,String name){
this.id=id;
this.name=name;
this.courses=new HashSet<CourseClass>();
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof StudentsClass))
return false;
StudentsClass other = (StudentsClass) obj;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
public int compareTo(StudentsClass o) {
return this.id.compareTo(o.id);
}
}
package 学生管理系统;
public class CourseClass {
public String id;
public String name;
public CourseClass(String id,String name){
this.id=id;
this.name=name;
}
public CourseClass() {
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof CourseClass))
return false;
CourseClass other = (CourseClass) obj;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
}
3，利用List进行增加课程，删除课程，修改课程等的操作
package 学生管理系统;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
public class ListTest {
//创建
public List coursesToSelect;
//构造器
public ListTest(){
this.coursesToSelect = new ArrayList();
}
public void testAdd(){
//加课
CourseClass cr1 = new CourseClass("1","数据结构");
coursesToSelect.add(cr1);
CourseClass temp = (CourseClass)coursesToSelect.get(0);
System.out.println("添加了课程:"+temp.id+":"+temp.name);
CourseClass cr2 = new CourseClass("2","c语言");
coursesToSelect.add(0, cr2);
CourseClass temp2 = (CourseClass)coursesToSelect.get(0);
System.out.println("添加了课程:"+temp2.id+":"+temp2.name);
CourseClass[] Course={new CourseClass("3","离散数学"),new CourseClass("4","汇编语言")};
coursesToSelect.addAll(Arrays.asList(Course));
CourseClass temp3 = (CourseClass)coursesToSelect.get(2);
CourseClass temp4 = (CourseClass)coursesToSelect.get(3);
System.out.println("添加了两门课程："+temp3.id+":"+temp3.name+";"+temp4.id+":"+temp4.name);
CourseClass[] Course1= {new CourseClass("5","高等数学"),new CourseClass("6","大学英语")};
coursesToSelect.addAll(2, Arrays.asList(Course1));
CourseClass temp5 = (CourseClass)coursesToSelect.get(2);
CourseClass temp6 = (CourseClass)coursesToSelect.get(3);
System.out.println("添加了两门课程："+temp5.id+":"+temp5.name+";"+temp6.id+":"+temp6.name);
}
public void test() {
int size = coursesToSelect.size();
for(int i=0;i<size;i++) {
//进行强制类型转化
CourseClass cr = (CourseClass)coursesToSelect.get(i);
System.out.println("课程"+i+":"+cr.id+":"+cr.name);
}
}
//迭代器输入方法
public void testIterator() {
Iterator it = coursesToSelect.iterator();
System.out.println("可选择的课程（通过迭代器访问）：");
while(it.hasNext()) {
CourseClass cr = (CourseClass) it.next();
System.out.println("课程"+":"+cr.id+":"+cr.name);
}
}
//利用foreach语句进行遍历
public void testForEach() {
System.out.println("可选择的课程（通过FOREACH访问）：");
for(Object obj:coursesToSelect) {
CourseClass cr = (CourseClass) obj;
System.out.println("课程"+":"+cr.id+":"+cr.name);
}
}
//进行修改操作
public void testModify() {
coursesToSelect.set(4, new CourseClass("7","毛概"));
}
//利用对象进行删除操作
public void testRmove1() {
System.out.println("通过对象进行删除");
CourseClass cr = (CourseClass) coursesToSelect.get(4);
System.out.println("我是课程："+cr.id+":"+cr.name);
coursesToSelect.remove(cr);
System.out.println("成功删除课程！！");
testForEach();
}
//利用索引值进行删除操作
public void testRmove2() {
// CourseClass cr = (CourseClass) coursesToSelect.get(4);
// System.out.println("我是课程："+cr.id+":"+cr.name);
System.out.println("通过索引值进行删除");
coursesToSelect.remove(4);
System.out.println("成功删除课程！！");
testForEach();
}
//进行删除，删除多位置的方法操作
public void testRmove3() {
System.out.println("删除4位置和5位置的课程");
CourseClass [] Course={(CourseClass) coursesToSelect.get(4),(CourseClass) coursesToSelect.get(5)};
//将Course数组转化成一个集合传递进去
coursesToSelect.removeAll(Arrays.asList(Course));
System.out.println("成功删除课程！！");
testForEach();
}
public static void main(String[] args) {
ListTest it = new ListTest();
it.testAdd();
it.test();
//it.testIterator();
//it.testForEach();
//it.testModify();
//it.testForEach();
//it.testRmove2();
it.testRmove3();
}
}
4，利用set集合进行删除，添加，查询操作
package 学生管理系统;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
public class SetTest {
//创建
public List <CourseClass> coursesToSelect;
//向屏幕读取
private Scanner console;
public StudentsClass student;
//进行构造
public SetTest() {
coursesToSelect = new ArrayList<CourseClass>();
console = new Scanner(System.in);
}
public void testAdd(){
//加课
CourseClass cr1 = new CourseClass("1","数据结构");
coursesToSelect.add(cr1);
CourseClass temp = (CourseClass)coursesToSelect.get(0);
//System.out.println("添加了课程:"+temp.id+":"+temp.name);
CourseClass cr2 = new CourseClass("2","c语言");
coursesToSelect.add(0, cr2);
CourseClass temp2 = (CourseClass)coursesToSelect.get(0);
//System.out.println("添加了课程:"+temp2.id+":"+temp2.name);
CourseClass[] Course={new CourseClass("3","离散数学"),new CourseClass("4","汇编语言")};
coursesToSelect.addAll(Arrays.asList(Course));
CourseClass temp3 = (CourseClass)coursesToSelect.get(2);
CourseClass temp4 = (CourseClass)coursesToSelect.get(3);
//System.out.println("添加了两门课程："+temp3.id+":"+temp3.name+";"+temp4.id+":"+temp4.name);
CourseClass[] Course1= {new CourseClass("5","高等数学"),new CourseClass("6","大学英语")};
coursesToSelect.addAll(2, Arrays.asList(Course1));
CourseClass temp5 = (CourseClass)coursesToSelect.get(2);
CourseClass temp6 = (CourseClass)coursesToSelect.get(3);
//System.out.println("添加了两门课程："+temp5.id+":"+temp5.name+";"+temp6.id+":"+temp6.name);
}
public void testForEach() {
System.out.println("可选择的课程（通过FOREACH访问）：");
for(Object obj:coursesToSelect) {
CourseClass cr = (CourseClass) obj;
System.out.println("课程"+":"+cr.id+":"+cr.name);
}
}
//查询是否包含此课程
public void testListContains() {
CourseClass course = coursesToSelect.get(0);
System.out.println("取得课程："+course.name);
System.out.println("备选课程是否包含课程："+course.name+","
+coursesToSelect.contains(course));
System.out.println("请输入课程名称：");
String name = console.next();
CourseClass course2 = new CourseClass();
course2.name = name;
System.out.println("新创建课程："+course2.name);
System.out.println("备选课程是否包含课程："+course2.name+","
+coursesToSelect.contains(course2));
//indexof来求出索引
if(coursesToSelect.contains(course2)) {
System.out.println("课程："+course2.name+"的索引位置为："+
coursesToSelect.indexOf(course2));
}
}
public void creatStudentAndSelect() {
//创建一个学生对象
student = new StudentsClass("1","小明");
System.out.println("欢迎学生："+student.name+"选课！");
//从键盘输入课程
Scanner console = new Scanner(System.in);
for(int i = 0;i<3;i++) {
System.out.println("请输入课程ID");
String courseId = console.next();
for(CourseClass cr :coursesToSelect) {
if(cr.id.equals(courseId)) {
student.courses.add(cr);
student.courses.add(null);
student.courses.add(cr);
}
}
}
}
//测试Set的contains方法
public void testSetContains() {
System.out.println("请输入学生已选的课程名：");
String name = console.next();
CourseClass course2 = new CourseClass();
course2.name = name;
System.out.println("新创建课程："+course2.name);
System.out.println("备选课程是否包含课程："+course2.name+","
+student.courses.contains(course2));
}
public static void main(String[] args) {
// TODO Auto-generated method stub
SetTest st = new SetTest();
st.testAdd();
st.testForEach();
st.testListContains();
// st.creatStudentAndSelect();
// st.testSetContains();
}
}
5，利用Map进行增加，删除，查询，修改操作
package 学生管理系统;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.Set;
public class MapTest {
public Map<String,StudentsClass>students;
//利用哈希键值对进行创建
public MapTest() {
this.students = new HashMap<String,StudentsClass>();
}
//进行学生的插入操作
public void testPut() {
Scanner console = new Scanner (System.in);
int i = 0;
while(i<3) {
System.out.println("请输入学生ID：");
String ID = console.next();
StudentsClass st = students.get(ID);
if(st == null) {
System.out.println("请输入学生姓名：");
String name = console.next();
StudentsClass newStudent = new StudentsClass(ID,name);
students.put(ID,newStudent);
System.out.println("成功添加学生："+students.get(ID).name);
i++;
}else {
System.out.println("该学生ID已经被占用！");
continue;
}
}
}
//利用keyset方法将key值放在一个集合中，然后利用key值进行遍历
public void testKeySet() {
Set<String>keySet = students.keySet();
//进行遍历
for(String stuID:keySet) {
StudentsClass st = students.get(stuID);
if(st != null) {
System.out.println("学生："+st.name);
}
}
}
//进行删除操作
public void testRmove() {
Scanner console = new Scanner(System.in);
while(true) {
System.out.println("请输入要删除的学生ID！");
String ID = console.next();
StudentsClass st = students.get(ID);
if(st == null) {
System.out.println("该ID不存在！");
continue;
}
students.remove(ID);
System.out.println("成功删除学生："+st.name);
break;
}
}
//通过entryset来遍历Map
public void testEntrySet() {
Set<Entry<String,StudentsClass>>entrySet = students.entrySet();
for(Entry<String,StudentsClass> entry:entrySet) {
System.out.println("取得键："+entry.getKey());
System.out.println("对应的值为："+entry.getValue().name);
}
}
//进行修改操作
public void testModify() {
System.out.println("请输入要修改的学生ID：");
Scanner console = new Scanner(System.in);
while(true) {
String stuID = console.next();
StudentsClass student = students.get(stuID);
if(student == null) {
System.out.println("该ID不存在！请重新输入！");
continue;
}
System.out.println("当前学生ID，所对应的学生为："+student.name);
System.out.println("请输入新的学生姓名:");
String name = console.next();
StudentsClass newStudent = new StudentsClass(stuID,name);
students.put(stuID,newStudent);
System.out.println("修改成功");
}
}
//通过键值或值进行查询操作
public void testContainsKeyOrValue() {
System.out.println("请输入要查询的学生ID：");
Scanner console = new Scanner(System.in);
String id = console.next();
System.out.println("您输入的学生ID为："+id+"在学生映射表中是否存在："+
students.containsKey(id)
);
if(students.containsKey(id)) {
System.out.println("对应的学生为："+students.get(id).name);
}
System.out.println("请输入要查询的学生姓名：");
String name = console.next();
if(students.containsValue(new StudentsClass(null,name)))
System.out.println("在学生映射表中确实包含学生："+name);
else
System.out.println("在学生映射表中不存在该学生");
}
public static void main(String[] args) {
// TODO Auto-generated method stub
MapTest mt = new MapTest();
mt.testPut();
mt.testKeySet();
// mt.testRmove();
// mt.testEntrySet();
// mt.testModify();
// mt.testEntrySet();
mt.testContainsKeyOrValue();
}
}
6.进行重载比较
package 学生管理系统;
import java.util.Comparator;
public class StudentComparator implements Comparator<StudentsClass> {
@Override
public int compare(StudentsClass o1, StudentsClass o2) {
// TODO Auto-generated method stub
return o1.name.compareTo(o2.name);
}
}
7，进行排序操作
package 学生管理系统;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
public class CollectionTest {
//利用Collection内部方法进行排序操作
public void testSort1() {
//进行整形排序
List<Integer>intergerList = new ArrayList<Integer>();
Random random = new Random();
Integer k;
for(int i = 0;i < 10; i++) {
do {
k = random.nextInt(100);
}while(intergerList.contains(k));
intergerList.add(k);
System.out.println("成功添加整数："+k);
System.out.println("--------排序前-------");
for(Integer integer:intergerList) {
System.out.println("元素："+integer);
}
Collections.sort(intergerList);
System.out.println("--------排序后-------");
for(Integer integer:intergerList)
System.out.println("元素："+integer);
}
}
//进行String排序
public void testSort2() {
List<String>stringList = new ArrayList<String>();
stringList.add("microsoft");
stringList.add("google");
stringList.add("lenovo");
System.out.println("--------排序前-------");
for(String string : stringList) {
System.out.println("元素："+string);
}
Collections.sort(stringList);
System.out.println("--------排序后-------");
for(String string : stringList) {
System.out.println("元素："+string);
}
}
//对StudentsClass类进行排序，这里就需要进行equal和hashcode的重载
public void testSort3() {
List<StudentsClass>StudentList = new ArrayList<StudentsClass>();
Random random = new Random();
StudentList.add(new StudentsClass(random.nextInt(1000)+"","mike"));
StudentList.add(new StudentsClass(random.nextInt(1000)+"","lucy"));
StudentList.add(new StudentsClass(random.nextInt(1000)+"","angel"));
System.out.println("--------排序前-------");
for(StudentsClass student:StudentList) {
System.out.println("学生："+student.id+student.name);
}
Collections.sort(StudentList);
System.out.println("--------排序后-------");
for(StudentsClass student:StudentList) {
System.out.println("学生："+student.id+student.name);
}
Collections.sort(StudentList,new StudentComparator());
System.out.println("----------按照姓名排序----------");
for(StudentsClass student:StudentList) {
System.out.println("学生："+student.id+student.name);
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
CollectionTest ct = new CollectionTest();
//ct.testSort1();
//ct.testSort2();
ct.testSort3();
}
}
8，辅助类。
package 学生管理系统;
public class ChildCourse extends CourseClass {
}