initialize Class- consturctors_custur-ctor-优快云博客

本文探讨了Java中从基类构造派生类对象的过程，包括不同构造函数的使用及如何通过super关键字调用基类构造函数。展示了当派生类构造函数未显式调用基类构造函数时，默认行为及其可能引发的问题。

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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 int i;

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 default construct
* 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....");
}

}