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<K,V>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<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++;
}
}
}
}
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<Student> list=new LinkedList<Student>();
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<score.length;i++){
list.add(new Student(score[i],name[i]));
}
Iterator<Student> iter=list.iterator();
TreeSet<Student> mytree=new TreeSet<Student>();
while(iter.hasNext()){
Student stu=iter.next();
mytree.add(stu);
}
Iterator<Student> te=mytree.iterator();
while(te.hasNext()) {
Student stu=te.next();
System.out.println(""+stu.name+" "+stu.english);
}
}
}
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<UDiscKey,UDisc> treemap= new TreeMap<UDiscKey,UDisc>();
int amount[]={1,2,4,8,16};
double price[]={867,266,390,556};
UDisc UDisc[]=new UDisc[4];
for(int k=0;k<UDisc.length;k++) {
UDisc[k]=new UDisc(amount[k],price[k]);
}
UDiscKey key[]=new UDiscKey[4] ;
for(int k=0;k<key.length;k++) {
key[k]=new UDiscKey(UDisc[k].amount);
}
for(int k=0;k<UDisc.length;k++) {
treemap.put(key[k],UDisc[k]);
}
int number=treemap.size();
Collection<UDisc> collection=treemap.values();
Iterator<UDisc> iter=collection.iterator();
while(iter.hasNext()) {
UDisc disc=iter.next();
System.out.println(""+disc.amount+"G "+disc.price+"元");
}
treemap.clear();
for(int k=0;k<key.length;k++) {
key[k]=new UDiscKey(UDisc[k].price);
}
for(int k=0;k<UDisc.length;k++) {
treemap.put(key[k],UDisc[k]);
}
number=treemap.size();
collection=treemap.values();
iter=collection.iterator();
while(iter.hasNext()) {
UDisc disc=iter.next();
System.out.println(""+disc.amount+"G "+disc.price+"元");
}
}
}
1． import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Xiti2 extends Applet implements ActionListener
{ TextField text1,text2;
Label label;
public void init()
{ text1=new TextField(10);
text2=new TextField(20);
Box box1=Box.createHorizontalBox();
Box box2=Box.createHorizontalBox();
Box boxV=Box.createVerticalBox();
box1.add(new Label("输入一个数回车确定:"));
box1.add(text1);
label=new Label("数的平方:");
box2.add(label);
box2.add(text2);
boxV.add(box1);
boxV.add(box2);
add(boxV);
text2.setEditable(false);
text1.addActionListener(this);
}
public void actionPerformed(ActionEvent e)
{ String number=e.getActionCommand();
try{ double n=Double.parseDouble(number);
double m=n*n;
label.setText(n+"的平方:");
text2.setText(""+m);
text1.setText("");
validate();
}
catch(NumberFormatException exp)
{ text2.setText(""+exp);
}
}
}
2． import java.applet.*;
import java.awt.*;
public class Rect extends Applet {
int w,h;
public void init() {
String s1=getParameter("width"); //从html得到"width"的值。
String s2=getParameter("height"); //从html得到"height"的值。
w=Integer.parseInt(s1);
h=Integer.parseInt(s2);
}
public void paint(Graphics g) {
g.drawRect(10,10,w,h);
}
}
/*<applet code= Rect.class width=280 height=500>
<Param name="width" value ="150">
<Param name="height" value ="175">
</applet>*/
