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 Student student ;

public void testAdd() {

//創(chuàng)建一個課程對象，并通過調(diào)用add方法，添加到備選課程List中

Course cr1=new Course("1","數(shù)據(jù)結(jié)構(gòu)");

CoursesToSelect.add(cr1);

Course temp=(Course)CoursesToSelect.get(0);

//System.out.println("添加了課程:"+temp.id+"."+temp.name);

Course cr2=new Course("2","C語言");

CoursesToSelect.add(1, cr2);

Course temp2=(Course)CoursesToSelect.get(0);

// System.out.println("添加了課程:"+temp2.id+"."+temp2.name);

// CoursesToSelect.add(cr1);

// Course temp0=(Course)CoursesToSelect.get(2);

// System.out.println("添加了課程:"+temp.id+"."+temp.name);

Course[] cour= {new Course("3","離散數(shù)學(xué)"),new Course("4","匯編語言")};

CoursesToSelect.addAll(Arrays.asList( cour));

Course temp3=(Course)CoursesToSelect.get(2);

Course temp4=(Course)CoursesToSelect.get(3);

// System.out.println("添加了兩門課程:"+temp3.id+":"+temp3.name+temp4.id+":"+temp4.name);

Course[] cour2= {new Course("5","高等數(shù)學(xué)"),new Course("6","大學(xué)英語")};

CoursesToSelect.addAll(2,Arrays.asList(cour2));

Course temp5=(Course)CoursesToSelect.get(2);

Course temp6=(Course)CoursesToSelect.get(3);

// System.out.println("添加了兩門課程:"+temp5.id+":"+temp5.name+temp6.id+":"+temp6.name);

}

public void testForEach() {

System.out.println("有如下課程待選:通過for each訪問");

for(Object obj:CoursesToSelect) {

Course cr=(Course)obj;

System.out.println("課程："+cr.id+":"+cr.name);

}

}

// public SetTest() {

// CoursesToSelect=new ArrayList<Cour>();

// console=new Scanner(System.in);

// }

/**

* 測試List的Contains方法

* @param args

*/

public void testListContains() {

//取得備選課程序列的第0個元素

Course course=CoursesToSelect.get(0);

//打印輸出couresToSelect是否包含course對象

System.out.println("取得課程:"+course.name);

System.out.println("備選課程中是否包含課程:"+course.name+","+CoursesToSelect.contains(course));

//提示輸入課程名稱

System.out.println("請輸入課程名稱：");

String name=console.next();

//創(chuàng)建一個新的課程對象，ID和名稱，于course對象完全一樣

Course course2=new Course();

course2.name=name;

System.out.println("新創(chuàng)建課程:"+course2.name);

System.out.println("備選課程中是否包含課程:"+course2.name+","+CoursesToSelect.contains(course2));

}

//創(chuàng)建學(xué)生對象并選課

public void creatStudentAndSelectCours() {

//創(chuàng)建一個學(xué)生對象

student=new Student("1","小明");

System.out.println("歡迎學(xué)生："+student.name+"選課!");

//創(chuàng)建一個Scanner對象，用來接收從鍵盤輸入的課程ID

console=new Scanner(System.in);

for(int i=0;i<3;i++){

System.out.println("請輸入課程ID:");

String courId=console.next();

for(Course cr:CoursesToSelect) {

if(cr.id.equals(courId)) {

student.courses.add(cr);

}

}

}

}

/**

* 測試Set的contains方法

* @param args

*/

public void testSetContains() {

//提示輸入課程名稱

System.out.println("請輸入學(xué)生已選的課程名稱");

String name=console.next();

//創(chuàng)建一個新的課程對象，ID和名稱，于course對象完全一樣

Course course2=new Course();

course2.name=name;

System.out.println("新創(chuàng)建課程:"+course2.name);

System.out.println("備選課程中是否包含課程:"+course2.name+","+student.Cour.contains(course2));

}

public static void main(String[] args) {

SetTest st=new SetTest();

st.testAdd();

//st.testListContains();

st.testForEach();

st.creatStudentAndSelectCours();

st.testSetContains();

}

?

public void testForeachForSet(Student student) {

//打印除數(shù)，學(xué)生所選的課程！

for(Course cr:student.Cour) {

System.out.println("選擇了課程："+cr.id+cr.name);

}

?

}

}

Exception in thread "main" java.lang.NullPointerException

at com.imooc.collection.SetTest.testAdd(SetTest.java:17)

at com.imooc.collection.SetTest.main(SetTest.java:119)