Cirry's Blog

构造函数

2019-09-24
技术
java
最后更新:2024-04-05
2分钟
367字

构造方法的定义

  • 构造方法名称必须与类名称保持一致。
  • 构造方法不允许设置任何的返回值类型,即:没有返回值定义。
  • 构造方法是在使用关键字new实例化对象的时候自动调用的。
  • 简单类的定义方法
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class Person{
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private String name;
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private int age;
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public Person(){
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this("dog",18);
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}
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public Person(String name){
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this(name, 28);
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}
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public Person(String name, int age){
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this.name = name;
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this.age = age;
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}
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public void getInfo (){
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System.out.println("my name is "+this.name+",my age is "+this.age) ;
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}
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public void setName(String name){
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this.name = name;
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}
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public void setAge(int age){
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this.age = age;
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}
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public String getName(){
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return this.name;
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}
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public Number getAge(){
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return this.age;
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}
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}
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public class JavaDemo {
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public static void main( String args []){
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Person per = new Person("ccc",25);
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per.getInfo();
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}
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}

带静态变量static的类构造

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class Book{
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private String name;
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private int bid ;
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private double price ;
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private static int count = 0;
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public Book(){
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}
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public Book(String name , double price){
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this.bid = count++;
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this.name = name;
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this.price = price;
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}
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public String getInfo(){
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return "book name:"+this.name+",book price:"+this.price;
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}
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public static int getCount (){
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return count;
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}
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}
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public class JavaDemo {
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public static void main(String args []){
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Book b3 = new Book("html", 100.00);
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Book b2 = new Book("html2", 222200.00);
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System.out.println(b3.getInfo());
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System.out.println(Book.getCount());
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}
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}

简单类的练习

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class User{
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private String name;
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private int no;
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public User(String name , int no){
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this.name = name;
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this.no = no;
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}
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public void setName(String name ){
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this.name = name;
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}
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public void setNo (int no ){
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this.no = no;
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}
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public String getName (){
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return this.name;
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}
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public int getNo(){
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return this.no;
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}
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public String getInfo(){
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return "my name is "+ this.name+",my no is "+this.no;
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}
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}
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public class Demo {
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public static void main(String args []){
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User user1 = new User("cirry", 1);
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User user2 = new User("winnie", 2);
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System.out.println(user1.getInfo());
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System.out.println(user2.getInfo());
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user1.setName("cirry666");
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System.out.println(user1.getNo());
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System.out.println(user1.getInfo());
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user2.setNo(2);
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System.out.println(user2.getInfo());
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}
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}
本文标题:构造函数
文章作者:Cirry
发布时间:2019-09-24
版权声明:本作品采用「署名-非商业性使用-相同方式共享 4.0 国际」许可协议进行许可。
感谢大佬送来的咖啡☕
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