Java2实用教程(第5版)最新答案-耿祥义

new GradientPaint(200,200,Color.red,200,180,Color.yellow); g_2d.setPaint(gradient_3); g_2d.fill(center_curve_1); } } }

public class E {

public static void main(String args[]) { JFrame f=new JFrame(); f.setSize(500,450); f.setVisible(true);

Flower canvas=new Flower(); f.add(canvas,\ f.validate();

f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); } }

5． import java.awt.*;

import javax.swing.*; import java.awt.geom.*; class Moon extends Canvas { public void paint(Graphics g)

{ Graphics2D g_2d=(Graphics2D)g; Ellipse2D ellipse1=

new Ellipse2D. Double (20,80,60,60), ellipse2=

new Ellipse2D. Double (40,80,80,80); g_2d.setColor(Color.white); Area a1=new Area(ellipse1), a2=new Area(ellipse2); a1.subtract(a2); //\差\ g_2d.fill(a1); } }

public class E {

public static void main(String args[]) { JFrame f=new JFrame(); f.setSize(500,450); f.setVisible(true); Moon moon=new Moon(); moon.setBackground(Color.black); f.add(moon,\

f.validate();

f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); } }

习题十五（第15章）

一、问答题

1．LinkedList使用链式存储结构，ArrayList使用顺序存储结构。

2．迭代器遍历在找到集合中的一个对象的同时，也得到待遍历的后继对象的引用，因此迭代器可以快速地遍历集合。 3．不是。

4．用HashMap来存储。 二、阅读程序 1．8。

2．ABCD。 三、编写程序 1. import java.util.*;

public class E {

public static void main(String args[]) {

Stack stack=new Stack(); 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(\ stack.push(temp); stack.push(F2); k++; } } } }

2. 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 E {

public static void main(String args[]) {

List list=new LinkedList(); int score []={65,76,45,99,77,88,100,79};

String name[]={\张三\李四\旺季\加戈\为哈\周和\赵李\将集\ for(int i=0;i

list.add(new Student(score[i],name[i])); }

Iterator iter=list.iterator();

TreeSet mytree=new TreeSet(); while(iter.hasNext()){ Student stu=iter.next(); mytree.add(stu); }

Iterator te=mytree.iterator(); while(te.hasNext()) { Student stu=te.next();

System.out.println(\ } } }

3. import java.util.*;

class UDiscKey implements Comparable { double key=0; UDiscKey(double d) { key=d;

}

public int compareTo(Object b) { UDiscKey disc=(UDiscKey)b; if((this.key-disc.key)==0) return -1; else

return (int)((this.key-disc.key)*1000); } }

class UDisc{ int amount; double price;

UDisc(int m,double e) { amount=m; price=e; } }

public class E {

public static void main(String args[ ]) {

TreeMap treemap= new TreeMap(); int amount[]={1,2,4,8,16}; double price[]={867,266,390,556}; UDisc UDisc[]=new UDisc[4]; for(int k=0;k

UDisc[k]=new UDisc(amount[k],price[k]); }

UDiscKey key[]=new UDiscKey[4] ; for(int k=0;k

key[k]=new UDiscKey(UDisc[k].amount); }

for(int k=0;k

treemap.put(key[k],UDisc[k]); }

int number=treemap.size();

Collection collection=treemap.values(); Iterator iter=collection.iterator(); while(iter.hasNext()) { UDisc disc=iter.next();

System.out.println(\元\