该文章Github地址：https://github.com/AntonyCheng/java-notes
在此介绍一下作者开源的SpringBoot项目初始化模板（Github仓库地址：https://github.com/AntonyCheng/spring-boot-init-template & CSDN文章地址：https://blog.csdn.net/AntonyCheng/article/details/136555245），该模板集成了最常见的开发组件，同时基于修改配置文件实现组件的装载，除了这些，模板中还有非常丰富的整合示例，同时单体架构也非常适合SpringBoot框架入门，如果觉得有意义或者有帮助，欢迎Star & Issues & PR！
上一章：由浅到深认识Java语言（30）：集合
41.阶段性练习
练习一：
- 创建一个动物类，定义种类，性别和属性；
- 从键盘录入数据，通过构造方法存入对象中，并调用对象的方法打印；
import java.util.Scanner;
public class Demo {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入物种名字：");
String species = sc.next();
System.out.println("请输入物种性别：");
char sex = sc.next().charAt(0);
Animal a = new Animal(species, sex);
a.printObject();
}
}
class Animal{
String species;
char sex;
public Animal(String species,char sex) {
this.species = species;
this.sex = sex;
}
public void printObject() {
System.out.println("物种："+species+" 性别："+sex);
}
}
打印效果如下：
练习二：
- 描述猫类，有属性 name、color、sex，通过构造方法给猫的属性赋值（一个是波斯猫，一个是土猫，其他属性自定）；
- 为猫类添加吃饭，抓老鼠方法，创建两只猫的对象；
- 分别调用猫的吃饭，抓老鼠方法；
public class Demo {
public static void main(String[] args) {
Cat bosi = new Cat("波斯猫", "红色", '雄');
Cat tumao = new Cat("土猫", "绿色", '雌');
bosi.eat(bosi.name);
tumao.catchMouse(tumao.name);
}
}
class Cat {
String name;
String color;
char sex;
public Cat() {
super();
// TODO Auto-generated constructor stub
}
public Cat(String name, String color, char sex) {
super();
this.name = name;
this.color = color;
this.sex = sex;
}
public void eat(String name) {
System.out.println(name+"吃饭！");
}
public void catchMouse(String name) {
System.out.println(name+"抓老鼠！");
}
}
打印效果如下：
练习三：
- 创建一个工具类，定义方法用来将基本数据类型转换成字符串；
public class Demo {
public static void main(String[] args) {
Tools t = new Tools();
byte b = 123;
String s1 = t.getStringFromByte(b);
short s = 1234;
String s2 = t.getStringFromShort(s);
char c = '1';
String s3 = t.getStringFromBChar(c);
int i = 12345;
String s4 = t.getStringFromInt(i);
float f = 12345.6f;
String s5 = t.getStringFromFloat(f);
double d = 1234567.8;
String s6 = t.getStringFromDouble(d);
long l = 12345678;
String s7 = t.getStringFromLong(l);
boolean bool = false;
String s8 = t.getStringFromBoolean(bool);
System.out.printf("%s %s %s %s %s %s %s %s",s1,s2,s3,s4,s5,s6,s7,s8);
}
}
class Tools {
public String getStringFromByte(byte num) {
return num+"";
}
public String getStringFromShort(short num) {
return num+"";
}
public String getStringFromBChar(char num) {
return num+"";
}
public String getStringFromInt(int num) {
return num+"";
}
public String getStringFromFloat(float num) {
return num+"";
}
public String getStringFromDouble(double num) {
return num+"";
}
public String getStringFromLong(long num) {
return num+"";
}
public String getStringFromBoolean(boolean num) {
return num+"";
}
}
打印效果如下：
练习四：
- 一档选秀节目，设计了一个平台共参与者展示才艺，不同的参与者有不同的才艺，使用多态编程模拟；
public class Demo {
public static void main(String[] args) {
People coder = new Coder("程序员",21);
People singer = new Singer("歌手",22);
People dancer = new Dancer("舞者",21);
System.out.println("请各位选手自我介绍一下：");
System.out.println("我叫"+coder.name+",今年"+coder.age+"岁;");
coder.haveRest();
Coder c = (Coder)coder;
c.playComputer();
System.out.println("我叫"+singer.name+",今年"+singer.age+"岁;");
singer.haveRest();
Singer s = (Singer)singer;
s.sing();
System.out.println("我叫"+dancer.name+",今年"+dancer.age+"岁;");
dancer.haveRest();
Dancer d = (Dancer)dancer;
d.dance();
}
}
class People{
String name;
int age;
public People(String name, int age) {
super();
this.name = name;
this.age = age;
}
public People() {
super();
// TODO Auto-generated constructor stub
}
public void haveRest() {
System.out.println("我会休息！");
}
}
class Coder extends People{
public Coder(String name, int age) {
super(name, age);
// TODO Auto-generated constructor stub
}
public void playComputer() {
System.out.println("我会玩电脑！");
}
}
class Singer extends People{
public Singer(String name, int age) {
super(name, age);
// TODO Auto-generated constructor stub
}
public void sing() {
System.out.println("我会唱歌！");
}
}
class Dancer extends People {
public Dancer(String name, int age) {
super(name, age);
// TODO Auto-generated constructor stub
}
public void dance() {
System.out.println("我会跳舞！");
}
}
打印效果如下：
练习五：
- 学生都有学习和做作业的能力，但是学习的方式不同，使用抽象类的方法模拟编程；
public class Demo {
public static void main(String[] args) {
Student good = new Good();
Student poor = new Poor();
good.name = "xiaochen";
good.age = 20;
System.out.println("我是"+good.name+" 年龄"+good.age);
good.studyMethod();
poor.name = "xiaowu";
poor.age = 20;
System.out.println("我是"+poor.name+" 年龄"+poor.age);
poor.studyMethod();
}
}
abstract class Student{
String name;
int age;
abstract void studyMethod();
}
class Good extends Student{
@Override
void studyMethod() {
// TODO Auto-generated method stub
System.out.println("卷！");
}
}
class Poor extends Student{
@Override
void studyMethod() {
// TODO Auto-generated method stub
System.out.println("摆！");
}
}
打印效果如下：
练习六：
- 创建一个乐器接口，定义演奏方法 play ，定义两个实现类（钢琴 Piano，小提琴 Violin），分别实现乐器接口并做出不同的演奏；
public class Demo {
public static void main(String[] args) {
Tools piano = new Piano();
Tools violin = new Violin();
piano.play();
violin.play();
}
}
interface Tools {
void play();
}
class Piano implements Tools {
@Override
public void play() {
// TODO Auto-generated method stub
System.out.println("演奏钢琴曲！");
}
}
class Violin implements Tools{
@Override
public void play() {
// TODO Auto-generated method stub
System.out.println("演奏小提琴曲！");
}
}
打印效果如下：
练习七：
- 国家规定，汽车必须能点火，能开动，国家将文件发送到汽车厂商的手里，厂商生产的汽车必须符合要求，可以有特性功能，编程模拟；
public class Demo {
public static void main(String[] args) {
CarShop1 c1 = new CarShop1(1,0);
CarShop2 c2 = new CarShop2(1,1);
c1.getLisence(c1.getName());
c2.getLisence(c2.getName());
}
}
class CarShop {
int canLaunch;
int canMove;
public CarShop() {
super();
// TODO Auto-generated constructor stub
}
public CarShop(int canLaunch, int canMove) {
super();
this.canLaunch = canLaunch;
this.canMove = canMove;
}
public void getLisence(String name) {
if (this.canLaunch != 0 && this.canMove != 0) {
System.out.println(name+"能够得到国家许可");
} else {
System.out.println(name+"不能得到国家许可");
}
}
}
class CarShop1 extends CarShop {
private String name = "CarShop1";
public String getName() {
return this.name;
}
public void Character() {
System.out.println("时速300km/h");
}
public CarShop1() {
super();
// TODO Auto-generated constructor stub
}
public CarShop1(int canLaunch, int canMove) {
super(canLaunch, canMove);
// TODO Auto-generated constructor stub
}
}
class CarShop2 extends CarShop {
private String name = "CarShop2";
public String getName() {
return this.name;
}
public void Character() {
System.out.println("时速320km/h");
}
public CarShop2() {
super();
// TODO Auto-generated constructor stub
}
public CarShop2(int canLaunch, int canMove) {
super(canLaunch, canMove);
// TODO Auto-generated constructor stub
}
}
打印效果如下：
练习八：
- 定义一个动物类，自定义属性；
- 定义吃饭和睡觉两个方法；
- 创建两个对象（小猫和小狗），分别调用吃饭和睡觉方法；
- 打印结果是：小猫吃小鱼干，甜甜地睡着了，小狗吃骨头，憨憨地睡着了；
class Demo {
public static void main(String[] args) {
Animal Cat = new Animal("小猫",2);
Animal Dog = new Animal("小狗",1);
System.out.println(Cat.name+Cat.eat("小鱼干")+","+Cat.sleep("甜甜")
+","+Dog.name+Dog.eat("骨头")+","+Dog.sleep("憨憨"));
}
}
class Animal {
String name;
int age;
public Animal() {
super();
// TODO Auto-generated constructor stub
}
public Animal(String name, int age) {
super();
this.name = name;
this.age = age;
}
public String sleep(String description) {
return description + "地睡着了";
}
public String eat(String thing) {
return "吃" + thing;
}
}
打印效果如下：
练习九：
- 统计一个字符串中大写字母字符，小写字母字符，数字字符出现的次数，其他字符出现的次数；
- ABCDEabcd123456!@#$%^
方法一：
import java.util.Scanner;
class Demo {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入要计数的字符串：");
String str = sc.next();
sc.close();
char ch[] = str.toCharArray();
int matchNum = 0;
int matchBig = 0;
int matchSmall = 0;
int matchOther = 0;
for (int i = 0;i<ch.length;i++) {
if(ch[i]>='a'&&ch[i]<='z') {
matchSmall++;
}
else if(ch[i]>='A'&&ch[i]<='Z') {
matchBig++;
}
else if(ch[i]>='1'&&ch[i]<='9') {
matchNum++;
}
else {
matchOther++;
}
}
System.out.println("数字："+matchNum);
System.out.println("大写字母："+matchBig);
System.out.println("小写字母："+matchSmall);
System.out.println("其他字符："+matchOther);
}
}
方法二：
import java.util.Scanner;
class Demo {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入需要计数的字符串：");
String str = sc.next();
sc.close();
char ch[] = str.toCharArray();
int matchNum = 0;
int matchBig = 0;
int matchSmall = 0;
int matchOther = 0;
for (int i = 0;i<ch.length;i++) {
String s = Character.toString(ch[i]);
if(s.matches("[1-9]")) {
matchNum++;
}else if(s.matches("[a-z]")) {
matchSmall++;
}else if(s.matches("[A-Z]")) {
matchBig++;
}else {
matchOther++;
}
}
System.out.println("数字："+matchNum);
System.out.println("大写字母："+matchBig);
System.out.println("小写字母："+matchSmall);
System.out.println("其他字符："+matchOther);
}
}
打印效果如下：
练习十：
-
把数组中的数据按照指定格式拼接成一个字符串
-
举例
int[] arr = {1,2,3};
-
输出结果 “[1,2,3]”
-
import java.util.Scanner;
class Demo {
public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
System.out.println("你要输入的数据长度：");
int n = sc.nextInt();
int[] arr = new int[n];
System.out.println("请输入你要格式化的数字：");
for (int i = 0; i < arr.length; i++) {
arr[i] = sc.nextInt();
}
sc.close();
System.out.println("格式化后输出为：");
System.out.print("[");
for (int i = 0; i < arr.length-1; i++) {
System.out.print(arr[i]+",");
}
System.out.print(arr[n-1]+"]");
}
}
打印效果如下：
练习十一：
- 把字符串反转
- “abc” ==> “cba”
import java.util.Scanner;
class Demo {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入要反转的字符串：");
String str = sc.next();
sc.close();
char[] ch = str.toCharArray();
int n = ch.length / 2;
for (int i = 0; i < ch.length; i++) {
if(i>=n) {
break;
}
char temp = ch[i];
ch[i] = ch[ch.length-1-i];
ch[ch.length-1-i] = temp;
}
System.out.println("反转后得：");
System.out.println(ch);
}
}
打印效果如下：
练习十二：
-
统计大串中小串出现的次数
- 大串：Adcddkiqooqkdddleef
- 小串：dd
方法一：
class Demo {
public static void main(String[] args) {
String str = "Adcddkiqooqkdddleef";
String mstr = "dd";
char[] cs = str.toCharArray();
char[] mcs = mstr.toCharArray();
int count = 0;
int b1 = 0;
int condition = mcs.length;
int b2 = 0;
for (int i = 0; i < cs.length; i++) {
if (i + mcs.length > cs.length - 1) {
break;
}
b1 = 0;
for (int j = 0; j < mcs.length; j++) {
if (cs[i + j] == mcs[j]) {
b1++;
}
}
if (b1 == mcs.length) {
count++;
}
}
while(condition>0) {
if(cs[cs.length-1]==mcs[condition-1]) {
b2++;
}
if(b2==mcs.length) {
count++;
}
condition--;
}
System.out.println("检测重复到" + count + "次");
}
}
打印效果如下：
方法二：
package top.sharehome.BigJava;
import java.util.Scanner;
public class Demo {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str = sc.next();
String str0 = sc.next();
int count = 0;
int index = 0;
while ((index = str.indexOf(str0)) != -1) {
count++;
str = str.substring(index+1,str.length());
}
System.out.println(count);
}
}
打印效果如下：
练习十三：
- 除去一个字符串中相邻重复的字符
- abbddAffeeEddcccwceaa ==> abdAfeEdcwcea
import java.util.Scanner;
class Demo {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入需要去重的字符串：");
String str = sc.next();
sc.close();
StringBuffer sb = new StringBuffer();
char[] charArray = str.toCharArray();
for (int i = 0; i < charArray.length; i++) {
if (i + 1 != charArray.length) {
if (charArray[i] != charArray[i + 1]) {
sb.append(charArray[i]);
}
}else {
sb.append(charArray[i]);
}
}
System.out.println("去除重复后：");
System.out.println(sb);
}
}
打印效果如下：
