initialize Class- consturctors-优快云博客

本文探讨了Java中基类与派生类之间的继承关系，特别关注构造方法的调用顺序，并通过代理类的实现展示了如何利用Java的多态特性。详细解释了在派生类中不显式调用基类构造方法时，编译器如何默认选择调用带有参数的构造方法。同时，通过实例演示了如何创建代理类来增强原有类的功能。

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package com.eric.object;

public class ConsturctsFromBaseClass {
public static void main(String args[]) {
DerivedClass dc=new DerivedClass();
DerivedClass dc2=new DerivedClass("Eric");
DerivedClass dc3=new DerivedClass(5);
}
}

class BaseClass {
public inti;

public BaseClass() {
System.out.println("base class no parameter construct!");
}

public BaseClass(int i) {
this.i = i;
System.out.println("base class parameter constructor output!");
}
}

class DerivedClass extends BaseClass {
// public DerivedClass(){
//
// }
/**
* if don't call super construct from Base class, it's will call default
* construct from BaseClass,if in BaseClass just have been define parameter
* construct, the complier will complain that can't find a defaultconstruct
* of the form BaseClass()
**/
public DerivedClass(int i) {
super(i);
System.out.println("Derived output....");
}
public DerivedClass(String name){
System.out.println("parameter is String Derived output.....");
}
public DerivedClass(){
System.out.println("empty parameter derived class constructor output....");
}

}