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1、习题解答第一章 作业题1public class Hellopublic static void main (String args )System.out.pintln(“早上好， good Morning”);2import java.applet.*;import java.awt.*;public class Boy extends Applet public void paint(Graphics g) g.setColor(Color.blue); g.drawString(你好,hello,12,30);第二章 作业题1public class ZuoYe2_1public st
2、atic void main (String args )char c=;System.out.println(字母+c+在 unicode 表中的顺序位置 :+(int)c);System.out.println(字母表：);while(c0)y=-1+3*x;System.out.println(y);3.2public class ZuoYe3_2public static void main(String args) int sum=0,m=3,n=7,a=1;while(a=10)sum=sum+a;i+;a=a*i;System.out.println(sum=+sum);8第四章
3、 作业题4.1class DengChaint start,d;DengCha()DengCha(int start,int d)this.start=start;this.d=d;void setStart(int s)start=s;void setD(int d)this.d=d;int getSum(int n) int sum=0,i=1;while(i=0)root1=(-b+Math.sqrt(disk)/(2*a);root2=(-b-Math.sqrt(disk)/(2*a);System.out.printf(方程的根:%f,%fn,root1,root2); elseSy
4、stem.out.printf(方程没有实根n);elseSystem.out.println(不是一元 2 次方程); public void setCoefficient(double a,double b,double c)this.a=a;this.b=b;SquareEquation.c=c;if(a!=0)boo=true; else boo=false;public class ZuoYe4_3public static void main(String args )SquareEquation equation1=new SquareEquation(4,5,1);Square
5、Equation equation2=new SquareEquation(3,5,-7);equation1.getRoots();equation2.getRoots();4.4import java.util.Scanner;class Aint f(int m,int n) if(m*n=160|age A=new HashSet(),B=new HashSet(),tempSet=new HashSet();A.add(new Integer(1);A.add(new Integer(2); A.add(new Integer(3);A.add(new Integer(4);B.ad
6、d(new Integer(1);B.add(new Integer(3); B.add(new Integer(7);B.add(new Integer(9);B.add(new Integer(11);tempSet=(HashSet)A.clone();tempSet.retainAll(B); System.out.println(交：);Iterator iter=tempSet.iterator();while(iter.hasNext()Integer te=iter.next();System.out.printf(%d，,te.intValue(); tempSet=(Has
7、hSet)A.clone(); tempSet.addAll(B); iter=tempSet.iterator();System.out.println(并：);while(iter.hasNext()Integer te=iter.next();System.out.printf(%d，,te.intValue();tempSet=(HashSet)A.clone(); tempSet.removeAll(B); System.out.println(差：); iter=tempSet.iterator();while(iter.hasNext()Integer te=iter.next(
8、);System.out.printf(%d，,te.intValue(); 7.5import java.util.*;class MyKey implements Comparabledouble number=0; MyKey(double number)this.number=number;public int compareTo(Object b)MyKey st=(MyKey)b;if(this.number-st.number)=0) return -1;elsereturn (int)(this.number-st.number)*1000);class 硬盘int size;
9、double price;硬盘(int n, double p)size=n;price=p;public class ZuoYe4_1public static void main(String args )int size=10,3,7,12,10,22,100,4,6,2;double price=1.2,9.56,2.4,9.3,16.77,12.66,7.4,5.5,5.6,8.9,1.9;硬盘 s=new 硬盘10;for(int i=0;i treemap=new TreeMap();for(int i=0;i collection=treemap.values();Iterat
10、or iter=collection.iterator();while(iter.hasNext()硬盘 te=iter.next();System.out.println(te.size+,+te.price);treemap.clear();for(int i=0;i list=new LinkedList();List cloneList=null;for(int k=1;k=0) m=m-1;random.seek(m);int c=random.readByte();if(c=0) System.out.print(char)c); else m=m-1; /一个汉字占 2 个字节r
11、andom.seek(m);byte cc=new byte2;random.readFully(cc);System.out.print(new String(cc); random.close();catch(IOException ee)5.import java.awt.*;import java.awt.event.*;import javax.swing.*; public class Xiti8_5 public static void main(String args) ComputerFrame fr=new ComputerFrame();fr.setTitle(计算);
12、class ComputerFrame extends JFrame implements ActionListener JTextField text1,text2,text3;JButton button1,button2,button3,button4;JLabel label;public ComputerFrame()setLayout(new FlowLayout();text1=new JTextField(10);text2=new JTextField(10);text3=new JTextField(10);label=new JLabel( ,JLabel.CENTER)
13、;label.setBackground(Color.green); add(text1);add(label);add(text2);add(text3); button1=new JButton(加); button2=new JButton(减);button3=new JButton(乘);button4=new JButton(除);add(button1);add(button2);add(button3);add(button4); button1.addActionListener(this); button2.addActionListener(this); button3.
14、addActionListener(this); button4.addActionListener(this); setSize(400,320);setVisible(true);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);validate(); public void actionPerformed(ActionEvent e) double n;if(e.getSource()=button1) double n1,n2; try n1=Double.parseDouble(text1.getText();n2=Double.parse
15、Double(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 n
