一、问答题
1．Frame容器的默认布局是BorderLayout布局。
2．不可以。
3．ActionEvent。
4．DocumentEvent。
5．5个。
6．MouseMotionListener。
二、选择题
1．C。2．A。3．A。4．D。5．C。
三、编程题
1． import java.awt.*;
import javax.swing.event.*;
import javax.swing.*;
import java.awt.event.*;
public class E {
public static void main(String args[]) {
Computer fr=new Computer();
}
}
class Computer extends JFrame implements DocumentListener {
JTextArea text1,text2;
int count=1;
double sum=0,aver=0;
Computer() {
setLayout(new FlowLayout());
text1=new JTextArea(6,20);
text2=new JTextArea(6,20);
add(new JScrollPane(text1));
add(new JScrollPane(text2));
text2.setEditable(false);
(text1.getDocument()).addDocumentListener(this);
setSize(300,320);
setVisible(true);
validate();
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
public void changedUpdate(DocumentEvent e) {
String s=text1.getText();
String []a =s.split("[^0123456789.]+");
sum=0;
aver=0;
for(int i=0;i<a.length;i++) {
try { sum=sum+Double.parseDouble(a[i]);
}
catch(Exception ee) {}
}
aver=sum/count;
text2.setText(null);
text2.append("\n和:"+sum);
text2.append("\n平均值:"+aver);
}
public void removeUpdate(DocumentEvent e){
changedUpdate(e);
}
public void insertUpdate(DocumentEvent e){
changedUpdate(e);
}
}
2. import java.awt.*;
import javax.swing.event.*;
import javax.swing.*;
import java.awt.event.*;
public class E {
public static void main(String args[]) {
ComputerFrame fr=new ComputerFrame();
}
}
class ComputerFrame extends JFrame implements ActionListener {
JTextField text1,text2,text3;
JButton buttonAdd,buttonSub,buttonMul,buttonDiv;
JLabel label;
public ComputerFrame() {
setLayout(new FlowLayout());
text1=new JTextField(10);
text2=new JTextField(10);
text3=new JTextField(10);
label=new JLabel(" ",JLabel.CENTER);
label.setBackground(Color.green);
add(text1);
add(label);
add(text2);
add(text3);
buttonAdd=new JButton("加");
buttonSub=new JButton("减");
buttonMul=new JButton("乘");
buttonDiv=new JButton("除");
add(buttonAdd);
add(buttonSub);
add(buttonMul);
add(buttonDiv);
buttonAdd.addActionListener(this);
buttonSub.addActionListener(this);
buttonMul.addActionListener(this);
buttonDiv.addActionListener(this);
setSize(300,320);
setVisible(true);
validate();
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
public void actionPerformed(ActionEvent e) {
double n;
if(e.getSource()==buttonAdd) {
double n1,n2;
try{ n1=Double.parseDouble(text1.getText());
n2=Double.parseDouble(text2.getText());
n=n1+n2;
text3.setText(String.valueOf(n));
label.setText("+");
}
catch(NumberFormatException ee)
{ text3.setText("请输入数字字符");
}
}
else if(e.getSource()==buttonSub) {
double n1,n2;
try{ n1=Double.parseDouble(text1.getText());
n2=Double.parseDouble(text2.getText());
n=n1-n2;
text3.setText(String.valueOf(n));
label.setText("-");
}
catch(NumberFormatException ee)
{ text3.setText("请输入数字字符");
}
}
else if(e.getSource()==buttonMul)
{double n1,n2;
try{ n1=Double.parseDouble(text1.getText());
n2=Double.parseDouble(text2.getText());
n=n1*n2;
text3.setText(String.valueOf(n));
label.setText("*");
}
catch(NumberFormatException ee)
{ text3.setText("请输入数字字符");
}
}
else if(e.getSource()==buttonDiv)
{double n1,n2;
try{ n1=Double.parseDouble(text1.getText());
n2=Double.parseDouble(text2.getText());
n=n1/n2;
text3.setText(String.valueOf(n));
label.setText("/");
}
catch(NumberFormatException ee)
{ text3.setText("请输入数字字符");
}
}
validate();
}
}
3. import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class E {
public static void main(String args[]){
Window win = new Window();
win.setTitle("使用MVC结构");
win.setBounds(100,100,420,260);
}
}
class Window extends JFrame implements ActionListener {
Lader lader; //模型
JTextField textAbove,textBottom,textHeight; //视图
JTextArea showArea; //视图
JButton controlButton; //控制器
Window() {
init();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
void init() {
lader = new Lader();
textAbove = new JTextField(5);
textBottom = new JTextField(5);
textHeight = new JTextField(5);
showArea = new JTextArea();
controlButton=new JButton("计算面积");
JPanel pNorth=new JPanel();
pNorth.add(new JLabel("上底:"));
pNorth.add(textAbove);
pNorth.add(new JLabel("下底:"));
pNorth.add(textBottom);
pNorth.add(new JLabel("高:"));
pNorth.add(textHeight);
pNorth.add(controlButton);
controlButton.addActionListener(this);
add(pNorth,BorderLayout.NORTH);
add(new JScrollPane(showArea),BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent e) {
try{
double above = Double.parseDouble(textAbove.getText().trim());
double bottom = Double.parseDouble(textBottom.getText().trim());
double height = Double.parseDouble(textHeight.getText().trim());
lader.setAbove(above) ;
lader.setBottom(bottom);
lader.setHeight(height);
double area = lader.getArea();
showArea.append("面积:"+area+"\n");
}
catch(Exception ex) {
showArea.append("\n"+ex+"\n");
}
}
}
class Lader {
double above,bottom,height;
public double getArea() {
double area = (above+bottom)*height/2.0;
return area;
}
public void setAbove(double a) {
above = a;
}
public void setBottom(double b) {
bottom = b;
}
public void setHeight(double c) {
height = c;
}
}
一、问答题
1．使用FileInputStream。
2．FileInputStream按字节读取文件，FileReader按字符读取文件。
3．不可以。
4．使用对象流写入或读入对象时，要保证对象是序列化的。
5．使用对象流很容易得获取一个序列化对象的克隆，只需将该对象写入到对象输出流，那么用对象输入流读回的对象一定是原对象的一个克隆。
二、选择题
1．C。2．B。
三、阅读程序
1．【代码1】：51。【代码2】：0。
2．【代码1】：3。【代码2】：abc。【代码3】：1。【代码4】：dbc。
3．上机实习题，解答略。
四、编程题
1． import java.io.*;
public class E {
public static void main(String args[]) {
File f=new File("E.java");;
try{ RandomAccessFile random=new RandomAccessFile(f,"rw");
random.seek(0);
long m=random.length();
while(m>=0) {
m=m-1;
random.seek(m);
int c=random.readByte();
if(c<=255&&c>=0)
System.out.print((char)c);
else {
m=m-1;
random.seek(m);
byte cc[]=new byte[2];
random.readFully(cc);
System.out.print(new String(cc));
}
}
}
catch(Exception exp){}
}
}
2. import java.io.*;
public class E {
public static void main(String args[ ]) {
File file=new File("E.java");
File tempFile=new File("temp.txt");
try{ FileReader inOne=new FileReader(file);
BufferedReader inTwo= new BufferedReader(inOne);
FileWriter tofile=new FileWriter(tempFile);
BufferedWriter out= new BufferedWriter(tofile);
String s=null;
int i=0;
s=inTwo.readLine();
while(s!=null) {
i++;
out.write(i+" "+s);
out.newLine();
s=inTwo.readLine();
}
inOne.close();
inTwo.close();
out.flush();
out.close();
tofile.close();
}
catch(IOException e){}
}
}
3. import java.io.*;
import java.util.*;
public class E {
public static void main(String args[]) {
File file = new File("a.txt");
Scanner sc = null;
double sum=0;
int count = 0;
try { sc = new Scanner(file);
sc.useDelimiter("[^0123456789.]+");
while(sc.hasNext()){
try{ double price = sc.nextDouble();
count++;
sum = sum+price;
System.out.println(price);
}
catch(InputMismatchException exp){
String t = sc.next();
}
}
System.out.println("平均价格:"+sum/count);
}
catch(Exception exp){
System.out.println(exp);
}
}
}
