Implicit super constructor xx() is undefined for default constructor
2015-04-24 00:24
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因为父类定义了一个有参的构造函数,此时编译器就不会调用默认的无参构造函数。
当子类继承时,必须在自己的构造函数显式调用父类的构造函数,才能确保子类在初始化前父类会被实例化。
如果你父类中有无参的构造函数,子类就不会强制要求调用,编译器会默认帮你调用父类的构造函数。
父类
子类
当子类继承时,必须在自己的构造函数显式调用父类的构造函数,才能确保子类在初始化前父类会被实例化。
如果你父类中有无参的构造函数,子类就不会强制要求调用,编译器会默认帮你调用父类的构造函数。
父类
classPerson{
protectedStringname;
protectedintage;
//你已经定义了自己的构造函数,此时编译器不会为你创建默认的构造函数
publicPerson(Stringname,intage){
this.name=name;
this.age=age;
}
publicvoidprint(){
System.out.println("Name:"+name+"/nAge:"+age);
}
}
子类
classStudentextendsPerson{
publicStudent(){//子类构造函数
//super();不行,因为你的父类没有无参的构造函数
super("a",1);
//显示调用父类的构造函数,而且必须是第一行调用
}
}
classTest{
publicstaticvoidmain(Stringargs[]){
}
}
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