从入门到精通习题

1、5.3public class Eval / 新建类public static void main(String args) / 主方法String regex = "135d9"if (text.matches(regex) System.out.println(text + "是合法的手机号");5.4public class Eval / 新建类public static void main(String args) / 主方法StringBuilder builder = new StringBuilder("a");for

2、(int i = 1; i <= 10; i+) builder.append(i);System.out.println(builder.toString();6.1import java.util.*;public class Eval / 创建类public static void main(String args) int arr1=new int1,2,3,4,5; int arr2 = Arrays.copyOf(arr1, 3); / 复制源数组中从下标0开始的3个元素到目的数组，从下标0的位置开始存储。 for(int i=0;i<arr1.length;i+) S

3、ystem.out.print(arr1i); System.out.println(); for(int j=0;j<arr2.length;j+) System.out.print(arr2j);System.out.println();6.2import java.util.*;public class Eval / 创建类public static void main(String args) int arr = new int 10, 2, 3, 4, 5, 6, 7, 8, 9 ;Arrays.sort(arr);System.out.println(arr0);6.3imp

4、ort java.util.*;public class Text / 创建类public static void main(String args) String arr = new String "ac", "bc", "dc", "yc" ;System.out.println("替换前：");for (String str : arr) System.out.print(str+"t");Arrays.fill(arr, 2, 3, "bb");S

5、ystem.out.println("n替换后：");for (String str2 : arr) System.out.print(str2+"t");6.4public class Eval / 创建类public static void main(String args) int arr=new int1,2,3,4,5,6,7,8,9;System.out.println("数组原有内容：");for(int i = 0;i<arr.length;i+)for(int j=0;j<arr.length;j+)Sy

6、stem.out.print(arrij);System.out.println();System.out.println("行列互换后数组内容：");for(int i = 0;i<arr.length;i+)for(int j=0;j<arr.length;j+)System.out.print(arrji);System.out.println();7.1package com.lzw;public class UseCase1 private String name;public String getName() return name;public v

7、oid setName(String name) = name;/另一个java文件package com.lzw;public class UseCase2 extends UseCase1public static void main(String args) UseCase1 u=new UseCase1();u.setName("123");System.out.println(u.getName();7.2package com.lzw;public class UseCase3 private float height;private flo

8、at width;public UseCase3(float height,float width)this.height=height;this.width=width;public float square()return height*width;public static void main(String args)UseCase3 u=new UseCase3(3.5f,4.5f);System.out.println(u.square();7.3package com.lzw;public class UseCase4 public static void main(String

9、args) for(int i=0;i<args.length;i+)System.out.println(i);8.1public class Getintpublic static void main(String args) Integer inte = new Integer(452);int myint = Value();System.out.println(myint);8.2public class CharacterCompare public static void main(String args) Character char1 = new Cha

10、racter('h');Character char2 = new Character('H');boolean b = char1.equals(char2);System.out.println(b);Character char3 = char1.toLowerCase(char1);Character char4 = char2.toLowerCase(char2);boolean bb = char3.equals(char4);System.out.println(bb);8.3public class CreateBoolean public st

11、atic void main(String args) Boolean b = new Boolean("ok");String str = b.toString();System.out.println("ok:" + str);b = new Boolean("true");str = b.toString();System.out.println("true:" + str);9.1package com.lzw;import java.util.*;public class RandomTest /*par

12、am args * 获取2到32之间的6个偶数，并且求这6个偶数的和 */public static double EvenNum(double num1,double num2)double s=0;int j=new int6;Random cres = new Random();for (int w = (int)num1,i=0; w <= (int)num2; w += 2) ji = cres.nextInt(int) num2);if (ji!=0&&ji % 2 = 0) System.out.println(ji);s += ji;i+;if(i=6)

13、break;return s;public static double EvenNum2(double num1,double num2)double s=0;int j=new int6;for(int i=0,w=0;i<20;i+)jw=(int)num1+(int)(Math.random()*(num2-num1);if (jw!=0&&jw % 2 = 0) System.out.println("打印2到32之间的偶数(不包括32)"+jw);s += jw;w+;if(w=6) break;return s;public static

14、void main(String args) System.out.println("和为："+EvenNum2(2,32);9.2package com.lzw;import java.text.*;public class RoundArea static public void SimpleFormat(String pattern, double value) /使用实例化对象时设置格式化模式DecimalFormat myFormat = new DecimalFormat(pattern);/实例化DecimalFormat对象String output = m

15、yFormat.format(value);/将数字进行格式化System.out.println(value + " " + pattern + " " + output); public static double GetRoundArea(double r)return Math.PI*Math.pow(r, 2);public static void main(String args) System.out.print("圆的面积为：");SimpleFormat("#.#",GetRoundArea(2)

16、;9.3package com.lzw;import java.math.*;public class UseCase /* * param args */public static BigDecimal div(double value1,double value2,int b,int r)if(b<0)System.out.println("b值必须大于等于0");BigDecimal b1=new BigDecimal(Double.toString(value1);BigDecimal b2=new BigDecimal(Double.toString(val

17、ue2);return b1.divide(b2,b,r);public static void main(String args) / TODO 自动生成方法存根UseCase u=new UseCase();System.out.println(u.div(-7.5,8.9,5,BigDecimal.ROUND_CEILING);System.out.println(u.div(-7.5,8.9,5,BigDecimal.ROUND_DOWN);System.out.println(u.div(-7.5,8.9,5,BigDecimal.ROUND_FLOOR);System.out.pr

18、intln(u.div(-7.5,8.9,5,BigDecimal.ROUND_HALF_DOWN);System.out.println(u.div(-7.5,8.9,5,BigDecimal.ROUND_HALF_EVEN);System.out.println(u.div(-7.5,8.9,5,BigDecimal.ROUND_HALF_UP);System.out.println(u.div(-7.5,8.9,5,BigDecimal.ROUND_UP);10.1package com.lzw;public abstract class UseCase3 abstract void d

19、oit();public static void main(String args)new UseCase3();10.2package com.lzw;public class UseCase2 public void doSomething()System.out.println("父类.doSomething()");public void doAnything()System.out.println("父类.doAnything()");public static void main(String args)UseCase2 u=new sub(

20、);u.doSomething();u.doAnything();class sub extends UseCase2public void doAnything()System.out.println("子类.doAnything()");10.3package com.lzw;public abstract class UseCase1 abstract void testAbstract();UseCase1()/（1）首先执行父类构造方法System.out.println("before testAbstract()");testAbstrac

21、t();/如果调用了抽象方法，调用子类覆盖的方法。这里调用Atest类的testAbstract（）方法System.out.println("after testAbstarcat()");public static void main(String args)new Atest();class Atest extends UseCase1private int i=1;/（2）使成员变量进行初始化void testAbstract()System.out.println("testAbstract()"+i);public Atest()/（3）调用

22、子类构造方法System.out.println(i);11.1package com.lzw;public class AnonymityInnerClass class OuterClass4public OutInterface doit(final String s)return new OutInterface()private int i=0;public int getValue()System.out.println(s);return i;public void f()System.out.println("f()");interface OutInter

23、face / 定义一个接口11.2package com.lzw;public class StaticInnerClass int x=100;static class Innervoid doitInner()/System.out.println("外部类"+x);public static void main(String args)System.out.println("a");11.3public class UseCase3 static class avoid f()System.out.println("f()");

24、public static void main(String args)UseCase3.a a=new a();a.f();12.1public class Brunt public static void main(String args) Student stu = new Student(); try stu.speak(1500); catch (MyException e) e.printStackTrace(); /3个类public class MyException extends Exception public MyException(String ErrorMessag

25、r) super(ErrorMessagr);public class Student public void speak(int m) throws MyException if(m > 1000) throw new MyException("参数太大了"); 12.2public class Brunt public static int count(int m,int n) return m * n; public static void main(String args) throws Exception try int result = count(123

26、15,57876876); System.out.println(result); catch (Exception e) e.printStackTrace(); 12.3public class Computer public static int getMaxComm(int m , int n) throws MyException if( m <= 0 |n<=0) throw new MyException("传递的参数不是正整数"); if(m < n) int temp = 0; temp = m; m = n; n = temp; int

27、 r = m % n; while(r!=0) m = n; n = r; r = m % n; return n; public static void main(String args) try int m = 122 , n= 0;int reslut = getMaxComm(m,n);System.out.println(m+" 和 "+n+"的最大共约数是："+reslut); catch (MyException e) e.printStackTrace();/另一个类public class MyException extends Exc

28、eption String message;public MyException(String ErrorMessagr) message = ErrorMessagr;public String getMessage()return message;13.1package com.lzw;import java.awt.*;import javax.swing.*;public class UseCase1 extends JFrame/* * */private static final long serialVersionUID = 1L;private JComboBox<Str

29、ing> comboBox;public static void main(String args) new UseCase1();public UseCase1() super();setVisible(true);setSize(200,150);setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);comboBox = new JComboBox<>();comboBox.addItem("红");comboBox.addItem("黄");comboBox.addI

30、tem("蓝");comboBox.addItem("黑");getContentPane().add(comboBox, BorderLayout.NORTH);final JPanel panel = new JPanel();getContentPane().add(panel, BorderLayout.CENTER);final JCheckBox checkBox = new JCheckBox();checkBox.setText("男");panel.add(checkBox);final JCheckBox chec

31、kBox_1 = new JCheckBox();checkBox_1.setText("女");panel.add(checkBox_1);final JPanel panel_1 = new JPanel();getContentPane().add(panel_1, BorderLayout.SOUTH);final JButton okButton = new JButton();okButton.setText("确定");panel_1.add(okButton);final JButton button_1 = new JButton();

32、button_1.setText("取消");panel_1.add(button_1);13.2package com.lzw;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class UseCase2 extends JFrame/* * */private static final long serialVersionUID = 1L;private String contents="列表1","列表2","列表3"

33、,"列表4","列表5"private JComboBox<String> jc=new JComboBox<>();private JButton jb=new JButton("提交");int count=0;public UseCase2() setSize(200, 100);setVisible(true);setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);Container cp=getContentPane();cp.setLa

34、yout(new FlowLayout();cp.add(jc);cp.add(jb);jb.addActionListener(new ActionListener()public void actionPerformed(ActionEvent arg0) if(count<contents.length)jc.addItem(contentscount+););public static void main(String args) new UseCase2();13.3package com.lzw;import java.awt.*;import java.awt.event.

35、*;import javax.swing.*;public class UseCase3 extends JFrame/* * */private static final long serialVersionUID = 1L;public UseCase3()setVisible(true);setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);setTitle("登录窗体");setBounds(300, 200, 300, 150);Container cp=getContentPane();cp.set

36、Layout(null);JLabel jl=new JLabel("用户名：");jl.setBounds(10, 10, 200, 18);final JTextField name=new JTextField();name.setBounds(80, 10, 150, 18);JLabel jl2=new JLabel("密码：");jl2.setBounds(10, 50, 200, 18);final JPasswordField password=new JPasswordField();password.setBounds(80, 50,

37、 150, 18);cp.add(jl);cp.add(name);cp.add(jl2);cp.add(password);JButton jb=new JButton("确定");jb.addActionListener(new ActionListener()public void actionPerformed(ActionEvent arg0) if(name.getText().trim().length()=0|new String(password.getPassword().trim().length()=0)JOptionPane.showMessage

38、Dialog(null, "用户名密码不允许为空");return;if(name.getText().trim().equals("mr")&&new String(password.getPassword().trim().equals("mrsoft")JOptionPane.showMessageDialog(null, "登录成功");elseJOptionPane.showMessageDialog(null, "用户名或密码错误"););jb.setBounds(8

39、0, 80, 60, 18);cp.add(jb);final JButton button = new JButton();button.setText("重置");button.addActionListener(new ActionListener()public void actionPerformed(ActionEvent arg0) / TODO 自动生成方法存根name.setText("");password.setText(""););button.setBounds(150, 80, 60, 18);getCon

40、tentPane().add(button);public static void main(String args) new UseCase3();14.1import java.util.*;public class Text public static void main(String args) List<Integer> list = new LinkedList<>();for(int i = 1 ;i<=100;i+)list.add(new Integer(i);list.remove(list.get(10);System.out.println("ok");14.2import java.util.*;public class Text public static void main(String args) Set<String> set = new HashSet<>(); /HashSet是Set的子接口 set.add