编程题代码,仅供参考
第一周 类与对象
分数
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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); } //print 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; } } } }
第二周 对象交互
有秒计时的数字时钟
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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; } }
第三周 对象容器
查找里程
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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(); } }
第四周 继承多态
媒体类
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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+" "); } }
课程相关代码
1、Shapes
抽象类Shape,抽象方法draw(参数为Graphics类对象)
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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 }
Shape的子类Rectangle,override Shape的draw方法
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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); } }
Shape的子类Circle,override Shape的draw方法
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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); } }
Shape的子类Line,override Shape的draw方法
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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); } }
Shape的子类Triangle,override Shape的draw方法
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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); } }
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
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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); } }
MyPic为测试类,测试绘制JFrame Jpanel,并在窗体上绘制Shape对象
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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(); } }
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())
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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); } }