Java 构造器

package com.neusoft.oop;
/**
* 构造函数(构造器)：它就是一种特殊的方法，主要的作用是可以给类中的变量进行初始化。
* 1.构造方法的名称 与类名相同
* 2.构造方法是没有返回值的
* 3.一般来说构造方法都是public的
*
* 构造方法如何调用：new ConstructorDemo()
* @author Administrator
*
*/
public class ConstructorDemo {

public ConstructorDemo(){
System.out.println("Constructor ........");
}

public int test1(){
System.out.println("test1......");
return 0;
}
public static void main(String[] args) {
new ConstructorDemo().test1();
}
}

package com.neusoft.oop;
/**
* 之前我们会将属性声明在类中，如何给属性赋值 对象名.属性名，这样做是不好的，因为直接操作了属性
* 如何将类中的属性进行初始化(赋值)
* 1.get/set方法
* 2.构造器
* @author Administrator
*
*/
public class ConstructorDemo2 {
private String username;
private String password;
private int age;
private String school;

public ConstructorDemo2(String username, String password, int age, String school) {
this.username = username;
this.password = password;
this.age = age;
this.school = school;
System.out.println("12345648915");
}

public static void main(String[] args) {
ConstructorDemo2 constructorDemo2 = new ConstructorDemo2();
constructorDemo2.username = "tom";
//可以给外部类使用，将属性加上private就可以隐藏
}

public String getUsername() {
return username;
}
//给属性设置一个值
public void setUsername(String username) {
this.username = username;

}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public String getSchool() {
return school;
}

public void setSchool(String school) {
this.school = school;
}
}

package com.neusoft.oop;

public class ConstructorDemo2Test {
public static void main(String[] args) {
ConstructorDemo2 constructorDemo2 = new ConstructorDemo2("tom", "123456", 30, "neusoft");
// constructorDemo2.setUsername("tom");
// String username = constructorDemo2.getUsername();
// System.out.println(username);
System.out.println(constructorDemo2.getUsername());

constructorDemo2.setAge(20);
int a = constructorDemo2.getAge();
System.out.println(a);

constructorDemo2.setPassword("123456");
String password = constructorDemo2.getPassword();
System.out.println(password);

constructorDemo2.setSchool("大连大学");
String school = constructorDemo2.getSchool();
System.out.println(school);

}

}