面向对象程序设计----JAVA语言（浙江大学MOOC） - 金色的省略号
编程题代码，仅供参考
第一周 类与对象
分数
import java.util.Scanner;public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
Fraction a = new Fraction(in.nextInt(), in.nextInt());
Fraction b = new Fraction(in.nextInt(),in.nextInt());
a.print();
b.print();
a.plus(b).print();
a.multiply(b).plus(new Fraction(5,6)).print();
a.print();
b.print();
in.close();
}
}
//new对象的时候调用构造
class Fraction
{
int a,b;
//构造
Fraction(int a, int b)
{
this.a = a;
this.b = b;
adb();//约分
}
//toDouble
double toDouble()
{
double d = (double)a/b;
return d;
}
//plus
Fraction plus(Fraction r)
{
int n = this.a*r.b +r.a*this.b;
int d = this.b * r.b;
return new Fraction(n,d);
}
//multiply
Fraction multiply(Fraction r)
{
int n = this.a*r.a;
int d = this.b*r.b;
return new Fraction(n,d);
}
void print()
{
if(a==b)
System.out.println(1);
else
System.out.println(a+"/"+b);
}
//约分函数
private void adb ()
{
int i = a > b ? b : a;
for (;i>1;i--)
{
if(a%i==0&&b%i==0)
{
a /= i;
b /= i;
}
}
}
}
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第二周 对象交互
有秒计时的数字时钟
public class Main { public static void main(String[] args) {
java.util.Scanner in = new java.util.Scanner(System.in);
Clock clock = new Clock(in.nextInt(), in.nextInt(), in.nextInt());
clock.tick();
System.out.println(clock);
in.close();
}
}
class Clock {
private Display s = new Display(60);
private Display m = new Display(60);
private Display h = new Display(24);
public Clock(int hour, int minute, int second)
{
s.setvalue(second);
m.setvalue(minute);
h.setvalue(hour);
}
public void tick()
{
if(s.increase())
{
if(m.increase())
{
h.increase();
}
}
}
public String toString()
{
String str = String.format("%02d:%02d:%02d",h.getvalue(),m.getvalue(),s.getvalue());
return str;
}
}
class Display {
private int value = 0;
private int limit = 0;
public Display(int limit)
{
this.limit = limit;
}
public boolean increase()
{
boolean b = false;
value++;
if (value == limit)
{
value = 0;
b = true;
}
return b;
}
public int getvalue()
{
return value;
}
public void setvalue(int x)
{
value = x;
}
}
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第三周 对象容器
查找里程
import java.util.ArrayList;import java.util.Scanner;
public class Main
{
public static void main(String[] args)
{
ArrayList<String> city = new ArrayList<String>();
Scanner in = new Scanner(System.in);
while(true)
{
String cityName = in.next();
if(cityName.equals("###")){
break;
}
city.add(cityName);
}
int [][] distance = new int [city.size()][city.size()];
for(int i = 0; i < city.size(); i++){
for(int j = 0; j < city.size(); j++){
distance[i][j] = in.nextInt();
}
}
int i = city.indexOf(in.next());
int j = city.indexOf(in.next());
System.out.println(distance[i][j]);
in.close();
}
}
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第四周 继承多态
媒体类
package dome;import java.util.ArrayList;
public class Database {
private ArrayList<Item> listItem = new ArrayList<Item>();
public void add(Item item){
listItem.add(item);
}
public void list(){
for(Item item:listItem){
item.print();
}
}
public static void main(String[] args) {
Database db = new Database();
db.add(new CD("I am a CD","Even",6,24,true,"good"));
db.add(new DVD("I am a DVD","Even",20,true,"wonderful"));
db.add(new Mp3("I am a Mp3","Even",20,true,"talented","Hello World"));
db.list();
}
}
package dome;
public class CD extends Item {
private String artist;
private int numofTrack;
public CD(String title, String artist, int numofTrack, int playingTime,boolean gotIt,
String comment) {
super(title, playingTime, gotIt, comment);
this.artist = artist;
this.numofTrack = numofTrack;
}
public static void main(String[] args) {}
public void print() {
super.print();
System.out.print("artist: "+artist+" ");
System.out.println("numofTrack: "+numofTrack);
}
}
package dome;
public class DVD extends Item {
private String director;
public DVD(String title, String director, int playingTime, boolean gotIt ,String comment) {
super(title, playingTime, gotIt , comment);
this.director = director;
}
public static void main(String[] args) {
}
public void print() {
super.print();
System.out.println("director: "+director);
}
}
package dome;
public class Mp3 extends Item{
private String lyics;
private String singer;
public Mp3(String title, String singer, int playingTime, boolean gotIt, String comment,
String lyics) {
super(title, playingTime, gotIt, comment);
this.lyics = lyics;
this.singer = singer;
}
public static void main(String[] args) {
}
public void print() {
super.print();
System.out.print("singer: "+singer+" ");
System.out.println("lyics: "+lyics);
}
}
package dome;
public class Item {
private String title;
private int playingTime;
private boolean gotIt;
private String comment;
public Item(String title, int playingTime, boolean gotIt ,String comment) {
super();
this.title = title;
this.playingTime = playingTime;
this.gotIt = true;
this.comment = comment;
}
public static void main(String[] args) {
}
public void print() {
System.out.print("title: "+title+" ");
System.out.print("playingTime: "+playingTime+" ");
System.out.print("gotIt: "+gotIt+" ");
System.out.print("comment: "+comment+" ");
}
}
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课程相关代码
1、Shapes
抽象类Shape，抽象方法draw（参数为Graphics类对象）
package shapes;import java.awt.Graphics;
//抽象类Shape
public abstract class Shape {
public abstract void draw(Graphics g);//抽象方法 draw
}
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Shape的子类Rectangle，override Shape的draw方法
package shapes;import java.awt.Graphics;
public class Rectangle extends Shape {
private int x;
private int y;
private int width;
private int height;
public Rectangle(int x, int y, int width, int height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
}
@Override
public void draw(Graphics g) {
g.drawRect(x, y, width, height);
}
}
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Shape的子类Circle，override Shape的draw方法
package shapes;import java.awt.Graphics;
public class Circle extends Shape {
private int x;
private int y;
private int radius;
public Circle(int x, int y, int radius)
{
this.x = x;
this.y = y;
this.radius = radius;
}
@Override
public void draw(Graphics g) {
g.drawOval(x-radius, y-radius, radius*2, radius*2);
}
}
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Shape的子类Line，override Shape的draw方法
package shapes;import java.awt.Graphics;
public class Line extends Shape {
private int x1;
private int y1;
private int x2;
private int y2;
public Line(int x1, int y1, int x2, int y2)
{
this.x1 = x1; this.y1 = y1;
this.x2 = x2; this.y2 = y2;
}
@Override
public void draw(Graphics g) {
g.drawLine(x1, y1, x2, y2);
}
}
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Shape的子类Triangle，override Shape的draw方法
package shapes;import java.awt.Graphics;
public class Triangle extends Shape {
private int[] x = new int[3];
private int[] y = new int[3];
public Triangle(int x1, int y1, int x2, int y2, int x3, int y3)
{
x[0] = x1; x[1] = x2; x[2] = x3;
y[0] = y1; y[1] = y2; y[2] = y3;
}
@Override
public void draw(Graphics g) {
g.drawPolygon(x, y, x.length);
}
}
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Picture类继承自JFrame类， 成员变量，高、宽、包含Shape对象的ArrayList容器，内部类ShapesPanel继承自Jpanel类，该类重写了paintComponent方法，draw Shape对象
package shapes;import java.awt.Graphics;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Picture extends JFrame {
private static final long serialVersionUID = 1L;
private int width;
private int height;
private ArrayList<Shape> listShape = new ArrayList<Shape>();
private class ShapesPanel extends JPanel {
private static final long serialVersionUID = 1L;
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
for ( Shape s : listShape )
{
s.draw(g);
}
}
}
public void add(Shape s)
{
listShape.add(s);
}
public Picture(int width, int height)
{
add(new ShapesPanel());
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.width = width;
this.height = height;
}
public void draw()
{
setLocationRelativeTo(null);
setSize(width, height);
setVisible(true);
}
}
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MyPic为测试类，测试绘制JFrame Jpanel，并在窗体上绘制Shape对象
package shapes;public class MyPic {
public static void main(String[] args)
{
Picture pic = new Picture(420,300);
Circle c1 = new Circle(320,40,80);
Rectangle r1 = new Rectangle(100, 100, 100, 100);
Triangle t1 = new Triangle(100, 100, 200, 100, 150, 50);
Line l1 = new Line(0,205,400,205);
Circle c2 = new Circle(200,200,50);
pic.add(c1);
pic.add(r1);
pic.add(t1);
pic.add(l1);
pic.add(c2);
pic.draw();
}
}
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相关知识：
Swing 是一个为Java设计的GUI工具包，是JAVA基础类的一部分，包括了图形用户界面（GUI）器件如：文本框，按钮，分隔窗格和表
Graphics类提供基本的几何图形绘制方法，主要有：画线段、画矩形、画圆、画带颜色的图形、画椭圆、画圆弧、画多边形等
理解 JFrame JPanel：什么是 JFrame JPanel ，它们都是容器， JFrame是顶级容器，可以把 JPanel放进去，JPanel有两个方法，一个是paint，一个是getPreferredSize，继承自它的类，覆盖这两个方法，paint是绘画，getPreferredSize是大小，只有JFrame，运行后，大小为0，放进JPanel运行后，为getPreferredSize的大小（JFrame要调用pack（））
import java.awt.Dimension;import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
//测试面板类TestJPanel
class TestJPanel extends JPanel{
//绘画override
@Override
public void paint(Graphics g) {
super.paint(g);
}
//绘画尺寸override
@Override
public Dimension getPreferredSize() {
//参数修改，改变JPanel的大小
return new Dimension(150,150);
}
}
//测试类（空）
public class Test {
public static void main(String[] args){
//new JPanel
TestJPanel testJPanel = new TestJPanel();
//创建窗框（带参数直接加标题）
JFrame frame = new JFrame("Test");
//窗框标题
//frame.setTitle("Hello");
//关闭按钮程序关闭
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//窗框可否变化
frame.setResizable(true);
// JPanel 放入窗框（绝对布局）
frame.add(testJPanel);
testJPanel.setLayout(null);
//按钮，放到JPanel
JButton btnNewButton = new JButton("按钮");
btnNewButton.setBounds(29, 55, 93, 23);
testJPanel.add(btnNewButton);
//关联getPreferredSize()
frame.pack();
//显示窗体
frame.setVisible(true);
}
}
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