一：什么是构造器

如果没有显示的定义构造器，如： 比如Person p=new Person(),这个Person就是构造器

构造器的作用2:初始化对象的属性

package com.xx.study; public class PersonTest { public static void main(String[] args) { Person p=new Person("小猪"); System.out.println(p.name); } } class Person{ String name; public Person(String s) { name=s; } }

二：构造器例题

例题1

Person.java

package com.xx.study; public class Person { private int age; private String name; public Person() { age=18; } public Person(String s,int a) { name=s; age=a; } public void setAge(int a){ if(a<0||a>130) { System.out.println("传入数据不合格"); return; } age=a; } public int getAge() { return age; } public void setName(String s) { name=s; } public String getName() { return name; } }

PersonTest.java

package com.xx.study; public class PersonTest { public static void main(String[] args) { Person p1=new Person(); System.out.println(p1.getAge()); Person p2=new Person("Tom",18); System.out.println(p2.getName()); } }

例题2：

TriAngel.java

package com.xx.study; public class TriAngel { private int base; private int height; //创建一个空参构造器 public TriAngel() { } //创建一个带参数的构造器 public TriAngel(int b,int h) { base=b; height=h; } public void setBase(int b) { base=b; } public int getBase() { return base; } public void setHeight(int h) { height=h; } public int getHeight() { return height; } public int result() { return height*base*1/2; } }

TriAngelTest.java

package com.xx.study; public class TriAngelTest { public static void main(String[] args) { TriAngel t1=new TriAngel();//空参 t1.setBase(12); t1.setHeight(1); System.out.println("base:"+t1.getBase()+"height:"+t1.getHeight()+"面积"+t1.result()); TriAngel t2=new TriAngel(12,2);//有参数 System.out.println("base:"+t2.getBase()+"height:"+t2.getHeight()+"面积"+t2.result()); } }

二：属性赋值

后面的覆盖前面的