Contains方法，查看序列中是否包含某个元素

package com.imooc.collection;
/**
* 课程类
* @author Monica
*
*/
public class Course {
public String id;
public String name;
public Course(String id,String name){
this.id = id;
this.name = name;
}
public Course(){

}
@Override
public boolean equals(Object obj){
if(this == obj){//通过双等号判断对象相等
return true;
}
if(obj == null)//如果obj等于空
return false;
if(!(obj instanceof Course))//ogj对象不是Course类型
return false;
//前面都通过了
Course course = (Course)obj;//强转为course对象
if(this.name == null){//通过名称判断是否为course对象，判断名称是否为空
if(course.name == null)//强转为course的对象是否为空，两个都为空，是相等的
return true;
else
return false;
}else{//当前的对象不为空
if(this.name.equals(course.name))//判断name是否相等
return true;
else//name不相等
return false;
}
}
}

package com.imooc.collection;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class SetTest {
public List<Course> coursesToSelect;

private Scanner console;

public SetTest(){
coursesToSelect = new ArrayList<Course>();
console = new Scanner(System.in);
}
/**
* 用于往coursesToSelect中添加备选课程
*/
public void testAdd(){
//创建一个课程对象，并通过调用add方法，添加到备选课程List中
Course cr1 = new Course("1","数据结构");
coursesToSelect.add(cr1);
//取出元素  get方法
Course temp = (Course)coursesToSelect.get(0);
//System.out.println("添加了课程："+temp.id+":"+temp.name);

Course cr2 = new Course("2","C语言");//提供索引位置，插入元素
coursesToSelect.add(0, cr2);
Course temp2 = (Course)coursesToSelect.get(0);
//System.out.println("添加了课程："+temp2.id+":"+temp2.name);

coursesToSelect.add(cr1);
//取出元素  get方法
Course temp0 = (Course)coursesToSelect.get(2);
//System.out.println("添加了课程："+temp.id+":"+temp.name);

//以下方法会抛出数组下标越界异常
//Course cr3 = new Course("3","Test");
//coursesToSelect.add(4,cr3);数组越界

Course[] course = {new Course("3","离散数学"),new Course("4","汇编语言")};
coursesToSelect.addAll(Arrays.asList(course));
Course temp3 = (Course)coursesToSelect.get(3);
Course temp4 = (Course)coursesToSelect.get(4);

//System.out.println("添加了两门课程："+temp3.id+":"+temp3.name+";"+temp4.id+":"+temp4.name);

Course[] course2 = {new Course("5","高等数学"),new Course("6","大学英语")};
coursesToSelect.addAll(2,Arrays.asList(course2));
Course temp5 = (Course)coursesToSelect.get(2);
Course temp6 = (Course)coursesToSelect.get(3);

//System.out.println("添加了两门课程："+temp5.id+":"+temp5.name+";"+temp6.id+":"+temp6.name);

}
/**
* 通过for each方法访问集合元素
* @param args
*/
public void testForEach(){
System.out.println("有如下课程待选（通过for each访问）：");
for(Object obj:coursesToSelect){
Course cr = (Course)obj;
System.out.println("课程："+cr.id+":"+cr.name);
}
}
/**
* 测试List的contains方法
* containsAll方法，是否包含多个元素
* @param args
*/
public void testListContains(){
//取得备选课程序列的第0个元素
Course course = coursesToSelect.get(0);
//打印输出courseToSelected是否包含course对象
System.out.println("取得课程："+course.name);
System.out.println("备选课程中是否包含课程："+course.name+","+coursesToSelect.contains(course));
//提示输入课程名称
System.out.println("请输入课程名称：");
String name = console.next();
//创建一个新的课程对象，ID和名称，与course对象完全一样
Course course2 = new Course();
course2.name = name;
System.out.println("新创建课程："+course2.name);
System.out.println("备选课程中是否包含课程："+course2.name+","+coursesToSelect.contains(course2));

}
public static void main(String[] args) {
// TODO Auto-generated method stub
SetTest st = new SetTest();
st.testAdd();
st.testListContains();
/*st.testForEach();
//创建一个学生对象
Student student = new Student("1","小王");
System.out.println("欢迎学生："+student.name+"选课！");
//创建要给Scanner对象，用来接收从键盘输入的课程ID
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(Course cr:st.coursesToSelect){
if(cr.id.equals(courseId)){
student.courses.add(cr);
*//**
* Set中，添加某个对象，无论添加多少次
* 最终只会保留一个该对象(的引用）,
* 并且，保留第一次添加的那一个
*//*
//student.courses.add(cr);
//student.courses.add(null);
}
}
}
st.testForEachForSet(student);*/
}
public void testForEachForSet(Student student){
//打印输出，学生所选的课程！
System.out.println("供选择了："+student.courses.size());
for(Course cr:student.courses){
System.out.println("选择了课程："+cr.id+":"+cr.name);
}
}

}