课下作业（选做）第十周
课下作业（选做）第十周
一 相关知识点总结
创建一个空的链表
List<Student> list = new LinkedList<Student>();
向链表中添加新的结点
list.add(new Student());
删除结点
list.remove("");
链表中数据的插入
list.add("");
链表中数据的排序
Collections.sort();
将list中的元素按升序排序
public static sort(List<E>list)
二 课上内容补做
排序
import java.util.*;
public class Example {
public static void main(String[] args) {
List<Student> list = new LinkedList<>();
list.add(new Student(20165217,"叶 佺",99,91,89));
list.add(new Student(20165218,"赵冰雨",76,66,95));
list.add(new Student(20165219,"王彦博",77,81,68));
list.add(new Student(20165220,"葛宇豪",89,45,66));
list.add(new Student(20165221,"谭 笑",82,80,86));
SortTotal_score sortBytotal_score = new SortTotal_score();
Collections.sort(list, sortBytotal_score);
SortID sortByID = new SortID();
Collections.sort(list, sortByID);
System.out.println("学号排序：");
for (Student student : list) {
System.out.println(student);
}
Collections.sort(list, sortBytotal_score);
System.out.println("成绩排序：");
for (Student student : list) {
System.out.println(student);
}
}
}
class Student {
private int id;//表示学号
private String name;//表示姓名
private int age;//表示年龄
private String sex;
private double computer_score;//表示计算机课程的成绩
private double english_score;//表示英语课的成绩
private double maths_score;//表示数学课的成绩
private double total_score;// 表示总成绩
private double ave_score; //表示平均成绩
@Override
public String toString() {
return " "+name+" "+id+" "+total_score;
}
public Student(int id, String name,double computer_score,
double english_score,double maths_score) {
this.id = id;
this.name = name;
this.computer_score = computer_score;
this.english_score = english_score;
this.maths_score = maths_score;
}
public int getId() {
return id;
}//获得当前对象的学号，
public double getComputer_score() {
return computer_score;
}//获得当前对象的计算机课程成绩,
public double getMaths_score() {
return maths_score;
}//获得当前对象的数学课程成绩,
public double getEnglish_score() {
return english_score;
}//获得当前对象的英语课程成绩,
public void setId(int id) {
this.id = id;
}// 设置当前对象的id值,
public void setComputer_score(double computer_score) {
this.computer_score = computer_score;
}//设置当前对象的Computer_score值,
public void setEnglish_score(double english_score) {
this.english_score = english_score;
}//设置当前对象的English_score值,
public void setMaths_score(double maths_score) {
this.maths_score = maths_score;
}//设置当前对象的Maths_score值,
public double getTotalScore() {
total_score=computer_score + maths_score + english_score;
return total_score;
}// 计算Computer_score, Maths_score 和English_score 三门课的总成绩。
public double getAveScore() {
return getTotalScore() / 3;
}// 计算Computer_score, Maths_score 和English_score 三门课的平均成绩。
}
class SortID implements Comparator<Student> {
@Override
public int compare(Student a, Student b) {
return a.getId() - b.getId();
}
}
class SortTotal_score implements Comparator<Student> {
@Override
public int compare(Student a, Student b) {
return (int)( a.getTotalScore() - b.getTotalScore());
}
}
单链表
import java.util.*;
public class Mylist {
public static void main(String [] args) {
//选用合适的构造方法，用你学号前后各两名同学的学号创建四个结点
Node<String> node1 =new Node<String>("20165217",null);
Node<String> node2 =new Node<String>("20165218",null);
Node<String> node3 =new Node<String>("20165220",null);
Node<String> node4 =new Node<String>("20165221",null);
//把上面四个节点连成一个没有头结点的单链表
node1.next=node2;
node2.next=node3;
node3.next=node4;
node4.next=node1;
//遍历单链表，打印每个结点的
Node<String> node =node1 ;
System.out.println("打印插入前的链表数据");
for (int i=0;i<4;i++) {
System.out.println(node.data.toString());
node = node.next;
}
//把你自己插入到合适的位置（学号升序）
//遍历单链表，打印每个结点的
System.out.println("打印插入后的链表数据");
node=node1;
Node<String> s=new Node<String>("20165219",null);
for(int i=0;i<5;i++){
System.out.println(node.data.toString());
node = node.next;
if(node==node2){
node2.next=s;
s.next=node3;
}
}
//从链表中删除自己
node=node1;
for(int i=0;i<4;i++){
node = node.next;
if(node==s){
s=null;
node2.next=node3;
node3.next=node4;
}
}
node =node1 ;
System.out.println("打印删除后的链表数据");
for (int i=0;i<4;i++) {
System.out.println(node.data.toString());
node = node.next;
}
}
}
class Node<String> //单链表结点类，T指定结点的元素类型
{
public String data; //数据域，存储数据元素
public Node<String> next; //地址域，引用后继结点
public Node(String data, Node<String> next) //构造结点，data指定数据元素，next指定后继结点
{
this.data = data; //T对象引用赋值
this.next = next; //Node<T>对象引用赋值
}
public Node()
{
this(null, null);
}
@Override
public java.lang.String toString() //返回结点数据域的描述字符串
{
return this.data.toString();
}
}
教材代码分析
一
class Cone<E> {
double height;
E bottom; //用泛型类E声明对象bottom
public Cone (E b) {
bottom=b; //给泛型类对象赋值
}
public void setHeight(double h) {
height=h;
}
public double computerVolume() {
String s=bottom.toString();//泛型变量只能调用从Object类继承的或重写的方法
double area=Double.parseDouble(s);
return 1.0/3.0*area*height;
}
}
class Rect {
double sideA,sideB,area;
Rect(double a,double b) {
sideA=a;
sideB=b;
}
public String toString() {
area=sideA*sideB;
return ""+area;
}
}
class Circle {
double area,radius;
Circle(double r) {
radius=r;
}
public String toString() { //重写Object类的toString()方法
area=radius*radius*Math.PI;
return ""+area;
}
}
public class Example15_1 {
public static void main(String args[]) {
Circle circle=new Circle(10);
Cone<Circle> coneOne=new Cone<Circle>(circle);//创建一个（圆）锥对象
coneOne.setHeight(16);
System.out.println(coneOne.computerVolume());
Rect rect=new Rect(15,23);
Cone<Rect> coneTwo=new Cone<Rect>(rect);//创建一个（方）锥对象
coneTwo.setHeight(98);
System.out.println(coneTwo.computerVolume());
}
}
二
import java.util.*;
public class Example15_2 {
public static void main(String args[]){
List<String> list=new LinkedList<String>();
//定义一个空链表
for(int i=0;i<=60096;i++){
list.add("speed"+i);
}
Iterator<String> iter=list.iterator(); //获取链表中的迭代器
long starttime=System.currentTimeMillis();
while(iter.hasNext()){
String te=iter.next();
}
//进行遍历
long endTime=System.currentTimeMillis();
long result=endTime-starttime;
System.out.println("使用迭代器遍历集合所用时间:"+result+"毫秒");
starttime=System.currentTimeMillis();
for(int i=0;i<list.size();i++){
String te=list.get(i);
}
endTime=System.currentTimeMillis();
result=endTime-starttime;
System.out.println("使用get方法遍历集合所用时间:"+result+"毫秒");
}
}
三
import java.util.*;
public class Example15_3 {
public static void main(String args[]){
LinkedList mylist=new LinkedList();//定义一个空链表
mylist.add("你"); //链表中的第一个节点
mylist.add("好"); //链表中的第二个节点
int number=mylist.size(); //获取链表的长度
for(int i=0;i<number;i++){
String temp=(String)mylist.get(i); //必须强制转换取出的数据
System.out.println("第"+i+"节点中的数据:"+temp);
}
Iterator iter=mylist.iterator();
while(iter.hasNext()) {
String te=(String)iter.next(); //必须强制转换取出的数据
System.out.println(te);
}
}
}
四
import java.util.*;
class Student implements Comparable {
int height=0;
String name;
Student(String n,int h) {
name=n;
height = h;
}
public int compareTo(Object b) { // 两个Student对象相等当且仅当二者的height值相等
Student st=(Student)b;
return (this.height-st.height);
}
}
public class Example15_4 {
public static void main(String args[ ]) {
List<Student> list = new LinkedList<Student>();
//定义一个空链表
list.add(new Student("张三",188));
list.add(new Student("李四",178));
list.add(new Student("周五",198));
//向链表中依次添加元素
Iterator<Student> iter=list.iterator();
System.out.println("排序前,链表中的数据");
while(iter.hasNext()){
Student stu=iter.next();
System.out.println(stu.name+ "身高:"+stu.height);
}
//对链表进行遍历
Collections.sort(list);
//进行升序排序
System.out.println("排序后,链表中的数据");
iter=list.iterator();
while(iter.hasNext()){
Student stu=iter.next();
System.out.println(stu.name+ "身高:"+stu.height);
}
Student zhaoLin = new Student("zhao xiao lin",178);
int index = Collections.binarySearch(list,zhaoLin,null);
if(index>=0) {
System.out.println(zhaoLin.name+"和链表中"+list.get(index).name+"身高相同");
}
}
}
五
import java.util.*;
public class Example15_5 {
public static void main(String args[ ]) {
List<Integer> list = new LinkedList<Integer>();
//定义一个空链表
for(int i=10;i<=50;i=i+10)
list.add(new Integer(i));
System.out.println("洗牌前,链表中的数据");
Iterator<Integer> iter=list.iterator();
while(iter.hasNext()){
Integer n=iter.next();
System.out.printf("%d\t",n.intValue());
}
//遍历链表
Collections.shuffle(list);
//按洗牌算法重新随机排列
System.out.printf("\n洗牌后,链表中的数据\n");
iter=list.iterator();
while(iter.hasNext()){
Integer n=iter.next();
System.out.printf("%d\t",n.intValue());
}
System.out.printf("\n再向右旋转1次后,链表中的数据\n");
Collections.rotate(list,1);
//旋转链表中的数据
iter=list.iterator();
while(iter.hasNext()){
Integer n=iter.next();
System.out.printf("%d\t",n.intValue());
}
}
}
六
import java.util.*;
public class Example15_6 {
public static void main(String args[]) {
Stack<Integer> stack=new Stack<Integer>();
//定义一个堆栈对象
stack.push(new Integer(1));
stack.push(new Integer(1));
//进行压栈
int k=1;
while(k<=10) {
for(int i=1;i<=2;i++) {
Integer F1=stack.pop();
int f1=F1.intValue();
Integer F2=stack.pop();
int f2=F2.intValue();
Integer temp=new Integer(f1+f2);
System.out.println(""+temp.toString());
stack.push(temp);
stack.push(F2);
k++;
}
}
}
}
八
import java.util.*;
class Student implements Comparable {
int english=0;
String name;
Student(int english,String name) {
this.name=name;
this.english=english;
}
public int compareTo(Object b) {
Student st=(Student)b;
return (this.english-st.english);
}
}
public class Example15_8 {
public static void main(String args[]) {
TreeSet<Student> mytree=new TreeSet<Student>();
//定义一个树集对象
Student st1,st2,st3,st4;
st1=new Student(90,"赵一");
st2=new Student(66,"钱二");
st3=new Student(86,"孙三");
st4=new Student(76,"李四");
mytree.add(st1);
mytree.add(st2);
mytree.add(st3);
mytree.add(st4);
//依次添加数据
Iterator<Student> te=mytree.iterator();
while(te.hasNext()) {
Student stu=te.next();
System.out.println(""+stu.name+" "+stu.english);
//遍历并打印数据
}
}
}
课后编程题
第一题
import java.util.*;
public class Series {
public static void main(String args[]) {
Stack<Integer> stack=new Stack<Integer>();
stack.push(new Integer(3));
stack.push(new Integer(8));
int k=1;
while(k<=10) {
for(int i=1;i<=2;i++) {
Integer F1=stack.pop();
int f1=F1.intValue();
Integer F2=stack.pop();
int f2=F2.intValue();
Integer temp=new Integer(2*f1+2*f2);
System.out.println(""+temp.toString());
stack.push(temp);
stack.push(F2);
k++;
}
}
}
}
第二题
import java.util.*;
public class bce {
public static void main(String args[]) {
TreeSet<Score> mytree = new TreeSet<>();
List<Score> mylist = new LinkedList<Score>();
mylist.add(new Score("赵一", 89));
mylist.add(new Score("钱二", 99));
mylist.add(new Score("孙三", 100));
mylist.add(new Score("李四", 92));
mylist.add(new Score("周五", 88));
//添加节点
Iterator<Score> score = mylist.iterator();
System.out.println("排序之前的：");
while (score.hasNext()) {
Score sco = score.next();
mytree.add(sco);
System.out.println(sco.name + " " + sco.english);
}
//将链表中的成绩放入树集中
System.out.println("排序之后的：");
Iterator<Score> te = mytree.iterator();
while (te.hasNext()) {
Score stu = te.next();
System.out.println("" + stu.name + " " + stu.english);
}
}
}
class Score implements Comparable {
int english = 0;
String name = "";
Score(String name, int english) {
this.name = name;
this.english = english;
}
@Override
public int compareTo(Object a) {
Score b = (Score) a;
return this.english - b.english;
}
}
第三题
import java.util.*;
class Sort implements Comparable {
double d=0;
Sort (double d) {
this.d=d;
}
@Override
public int compareTo(Object b) {
Sort st=(Sort) b;
if((this.d-st.d)==0) {
return -1;
}
else {
return (int) ((this.d - st.d) * 1000);
}
}
}
class U {
String name="";
double speed,capacity;
U(String name,double speed,double capacity) {
this.name=name;
this.capacity=capacity;
this.speed=speed;
}
}
public class PriceSort {
public static void main(String args[ ]) {
TreeMap<Sort,U> treemap= new TreeMap<Sort,U>();
String name[]={"A","B","C","D","E","F","G","H","I","J"};
double speed[]={111,100,101,345,213,433,565,333,454,454};
double capacity[]={4,10,32,64,128,34,68,120,112,1024};
U u[]=new U[10];
for(int k=0;k<u.length;k++) {
u[k]=new U(name[k],speed[k],capacity[k]);
}
Sort key[]=new Sort[10] ;
for(int k=0;k<key.length;k++) {
key[k]=new Sort(u[k].speed);
}
for(int k=0;k<u.length;k++) {
treemap.put(key[k],u[k]);
}
System.out.println("按speed排序:");
Collection<U> collection=treemap.values();
Iterator<U> iter=collection.iterator();
while(iter.hasNext()) {
U stu=iter.next();
System.out.println("品牌"+stu.name+"speed："+stu.speed);
}
treemap.clear();
for(int k=0;k<key.length;k++) {
key[k]=new Sort(u[k].capacity);
}
for(int k=0;k<u.length;k++) {
treemap.put(key[k],u[k]);
}
System.out.println("按capacity排序:");
collection=treemap.values();
iter=collection.iterator();
while(iter.hasNext()) {
U stu=(U)iter.next();
System.out.println("品牌"+stu.name+" capacity ："+stu.capacity);
}
}
}
