代码:
public class Dog{
static int age;
static String name;
static String breed;
public Dog(String name,int age,String breed){
this.name=name;
this.age=age;
this.breed=breed;
}
public Dog(String name,int age){
this(name,age,"greed");
}
public static void main(String args[]){
Dog high=new Dog("luffy",19,"pomerian");
Dog low=new Dog("gold",32,"german shepherd");
System.out.println(low.name+" "+low.age+" "+low.breed);
System.out.println(high.name+" "+high.age+" "+high.breed);
}
}
输出: gold 32 german shepherd
gold 32 german shepherd
虽然我正在创建两个对象实例,但只打印其中一个的字段。错误在哪里?
您已经使用了静态访问修饰符,并且静态变量为每个类对象共享内存。如果你不想要,那么只需从年龄,名称,品种中删除静态
public class Dog{
int age;
String name;
String breed;
public Dog(String name,int age,String breed){
this.name=name;
this.age=age;
this.breed=breed;
}
public Dog(String name,int age){
this(name,age,"greed");
}
public static void main(String args[]){
Dog high=new Dog("luffy",19,"pomerian");
Dog low=new Dog("gold",32,"german shepherd");
System.out.println(low.name+" "+low.age+" "+low.breed);
System.out.println(high.name+" "+high.age+" "+high.breed);
}
}
所有
static
字段都是共享的(static
字段是按类的(,但您希望实例字段(每个实例(。改变
static int age;
static String name;
static String breed;
自
private int age;
private String name;
private String breed;
您可能应该有访问器(get
之三(方法 - 如果您添加toString()
,您的打印将得到简化。喜欢
@Override
public String toString() {
return name + " " + age + " " + breed;
}
然后你可以print
System.out.println(low);
System.out.println(high);
在您的代码中将静态更改为私有:
示例 :
public class Dog{
private int age;
private String name;
private String breed;
public Dog(String name,int age,String breed){
this.name=name;
this.age=age;
this.breed=breed;
}
public Dog(String name,int age){
this(name,age,"greed");
}
}
public static void main(String args[]){
Dog high=new Dog("luffy",19,"pomerian");
Dog low=new Dog("gold",32,"german shepherd");
System.out.println(low.name+" "+low.age+" "+low.breed);
System.out.println(high.name+" "+high.age+" "+high.breed);
}
}
输出:
luffy 19 pomerian
gold 32 german shepherd
还有 :
public class Dog{
private int age;
private String name;
private String breed;
public Dog(String name,int age,String breed){
this.name=name;
this.age=age;
this.breed=breed;
}
public Dog(String name,int age){
this(name,age,"greed");
}
void toStrig (){
System.out.println(name+" "+ age+" "+breed);
}
public static void main(String args[]){
Dog high=new Dog("luffy",19,"pomerian");
Dog low=new Dog("gold",32,"german shepherd");
high.toStrig();
low.toStrig();
}
}
输出:
luffy 19 pomerian
gold 32 german shepherd