在Java里面，每一个类都会隐式地继承object类，而在object类里面有toString方法，这个就是用来输出类地地址。
System.out.println(this) 它会自动调用this对象的toString方法，所以若不重写toString方法地话，就会调用object类地toString方法，也就是输出当前对象的地址。
示例：
package test1;
public class Student {
private int price;
private String category;
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
public Student(int price, String category) {
this.price = price;
this.category = category;
}
//重写toString方法
public String toString(){
return "price:"+price+"category:"+category;
}
}
输出Student
package test1;
public class StudentTest {
public static void main(String[] args) {
Student st=new Student(1,"category");
System.out.print(st);
}
}
结果 price:1category:category
若不重写toString方法则输出 test1.Student@142bece
