Java面向对象程序设计课后答案(4)

System.out.println("请输入第一个日期的年份 月份 日期 ，每输入一个数回车确认"); year1= reader.nextInt(); month1= reader.nextInt(); day1= reader.nextInt();

System.out.println("请输入第二个日期的年份 月份 日期 ，每输入一个数回车确认"); year2= reader.nextInt(); month2= reader.nextInt(); day2= reader.nextInt();

Calendar calendar=Calendar.getInstance(); calendar.set(year1,month1,day1); long timeYear1=calendar.getTimeInMillis(); calendar.set(year2,month2,day2); long timeYear2=calendar.getTimeInMillis();

long 相隔天数=Math.abs((timeYear1-timeYear2)/(1000*60*60*24));

System.out.println(""+year1+"年"+month1+"月"+day1+"日和"+

year2+"年"+month2+"月"+day2+"日相隔"+相隔天数+"天"); } } 10．

public class Xiti10

{ public static void main(String args[]) { double a=0,b=0,c=0; a=12; b=24;

c=Math.max(a,b); System.out.println(c); c=Math.min(a,b); System.out.println(c); c=Math.pow(2,3); System.out.println(c); c=Math.abs(-0.123); System.out.println(c); c=Math.asin(0.56); System.out.println(c); c=Math.cos(3.14); System.out.println(c); c=Math.exp(1); System.out.println(c); c=Math.log(8); System.out.println(c); } }

习题10

1．BorderLayout布局。 2．不可以。 3．A,C。 4．

import java.util.StringTokenizer; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Xiti4

{ public static void main(String args[]) { ComputerFrame fr=new ComputerFrame(); fr.setTitle("计算的窗口"); } }

class ComputerFrame extends JFrame implements TextListener { TextArea text1,text2; int count=1;

double sum=0,aver=0; public ComputerFrame() { setLayout(new FlowLayout()); text1=new TextArea(6,20); text2=new TextArea(6,20); add(text1); add(text2);

text2.setEditable(false); text1.addTextListener(this); setSize(300,320); setVisible(true);

addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); validate(); }

public void textValueChanged(TextEvent e) { String s=text1.getText(); sum=0; aver=0;

StringTokenizer fenxi=new StringTokenizer(s," ,'\\n'"); int n=fenx

i.countTokens(); count=n;

double a[]=new double[n]; for(int i=0;i<=n-1;i++)

{ String temp=fenxi.nextToken(); try { a[i]=Double.parseDouble(temp); sum=sum+a[i]; }

catch(Exception ee) { count--; } }

aver=sum/count; text2.setText(null);

text2.append("\\n和:"+sum); text2.append("\\n平均值:"+aver); } } 5．

import java.applet.*; import java.awt.*; import java.awt.event.*; public class Xiti5

{ public static void main(String args[]) { ComputerFrame fr=new ComputerFrame(); fr.setTitle("计算"); } }

class ComputerFrame extends Frame implements ActionListener { TextField text1,text2,text3;

Button button1,button2,button3,button4; Label label;

public ComputerFrame() {setLayout(new FlowLayout()); text1=new TextField(10); text2=new TextField(10); text3=new TextField(10);

label=new Label(" ",Label.CENTER); label.setBackground(Color.green); add(text1); add(label); add(text2); add(text3);

button1=new Button("加"); button2=new Button("减"); button3=new Button("乘"); button4=new Button("除"); add(button1); add(button2); add(button3); add(button4);

button1.addActionListener(this); button2.addActionListener(this); button3.addActionListener(this); button4.addActionListener(this); setSize(300,320); setVisible(true);

addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); validate(); }

public void actionPerformed(ActionEvent e) { double n;

if(e.getSource()==button1) { 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()==button2) { 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()==button3) {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()==button4) {double n1,n

2;

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(); } } 6．

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Xiti6

{ public static void main(String args[]) { new WindowPanel(); } }

class Mypanel extends JPanel implements ActionListener