package?frameWork;

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

public?class?SetTest?{
????public?List<ArrayListStudent>?coursesToSelect;

????public?SetTest()?{
????????coursesToSelect?=?new?ArrayList<ArrayListStudent>();
????}

????public?void?testAdd()?{
????????//創(chuàng)建一個(gè)課程對象，并通過調(diào)用add方法，添加到備選課程List中
????????ArrayListStudent?cr1?=?new?ArrayListStudent("1",?"數(shù)據(jù)結(jié)構(gòu)");
????????coursesToSelect.add(cr1);
????????//這里添加（ArrayListStudent）的原因是對象存入集合后類型變?yōu)閛bject，這里強(qiáng)制轉(zhuǎn)換對象的類型
????????ArrayListStudent?temp?=?(ArrayListStudent)?coursesToSelect.get(0);
????????//System.out.println("添加課程："?+?temp.id?+?":"?+?temp.name);

????????ArrayListStudent?cr2?=?new?ArrayListStudent("2",?"Java");
????????coursesToSelect.add(1,?cr2);
????????ArrayListStudent?temp2?=?(ArrayListStudent)?coursesToSelect.get(1);
????????//System.out.println("添加課程："?+?temp2.id?+?":"?+?temp2.name);

????????//拋出數(shù)組下標(biāo)越界拋出異常
????????//ArrayListStudent?cr3?=?new?ArrayListStudent("3","C++");
????????//coursesToSelect.add(4,cr3);

????????ArrayListStudent[]?arrayListStudents?=?{
????????????????new?ArrayListStudent("3",?"離散數(shù)學(xué)"),?new?ArrayListStudent("4",?"匯編語言")
????????};
????????coursesToSelect.addAll(Arrays.asList(arrayListStudents));
????????ArrayListStudent?temp3?=?(ArrayListStudent)?coursesToSelect.get(2);
????????ArrayListStudent?temp4?=?(ArrayListStudent)?coursesToSelect.get(3);
????????//System.out.println("添加課程："?+?temp3.id?+?":"?+?temp3.name
????????//+?";"?+?temp4.id?+?":"?+?temp4.name);

????????ArrayListStudent[]?arrayListStudents2?=?{
????????????????new?ArrayListStudent("5",?"微分幾何"),?new?ArrayListStudent("6",?"數(shù)值分析")
????????};
????????coursesToSelect.addAll(2,?Arrays.asList(arrayListStudents2));
????????ArrayListStudent?temp5?=?(ArrayListStudent)?coursesToSelect.get(2);
????????ArrayListStudent?temp6?=?(ArrayListStudent)?coursesToSelect.get(3);
//????????System.out.println("添加課程："?+?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)?{
????????????ArrayListStudent?cr?=?(ArrayListStudent)?obj;
????????????System.out.println("課程："?+?cr.id?+?":"?+?cr.name);
????????}
????}


????public?static?void?main(String[]?args)?{
????????SetTest?st?=?new?SetTest();
????????st.testAdd();
????????st.testForEach();
????????//創(chuàng)建一個(gè)新的學(xué)生對象
????????Student?student?=?new?Student("1",?"章北海");
????????System.out.println("你好！"?+?student.name?+?"請選課");
????????//創(chuàng)建一個(gè)Scanner對象，接收鍵盤輸入的ID
????????Scanner?console?=?new?Scanner(System.in);
????????//創(chuàng)建一個(gè)循環(huán)，循環(huán)三次，將輸入的課程id加入到學(xué)生選課中
????????for?(int?i?=?0?;?i?<?3?;?i++)?{
????????????System.out.print("請輸入課程id：");
????????????String?courseID?=?console.next();
????????????for?(ArrayListStudent?cr?:?st.coursesToSelect)?{
????????????????if?(cr.id.equals(courseID))?{
????????????????????student.arrayListStudents.add(cr);
????????????????}
????????????}
????????}
????????st.testForEachForSet(student);
????}

????public?void?testForEachForSet(Student?student)?{
????????//循環(huán)完畢后打印輸出學(xué)生所選的課程
????????for?(ArrayListStudent?cr?:?student.arrayListStudents)?{
????????????System.out.println("選擇的課程為："?+?cr.id?+?":"?+?cr.name);
????????}

????}
}

輸出為:

有如下課程待選(通過for?each訪問)：
課程：1:數(shù)據(jù)結(jié)構(gòu)
課程：2:Java
課程：5:微分幾何
課程：6:數(shù)值分析
課程：3:離散數(shù)學(xué)
課程：4:匯編語言
你好！章北海請選課
請輸入課程id：1
請輸入課程id：2
請輸入課程id：3
選擇的課程為：3:離散數(shù)學(xué)
選擇的課程為：2:Java
選擇的課程為：1:數(shù)據(jù)結(jié)構(gòu)

如圖，請問為什么我輸入的課程id是1,2,3? 但是輸出是確實(shí)3,2,1反著的。。