Java 创建对象

public class P3(){
public int num1 = 1;
public int num2 = 2;
}

public class subP3 extends P3(){
public subP3(){
super();
this.num2 = 3;
}

public void print(){
System.out.println(num1);
System.out.println(num2);
｝

public static void main(String args[]){
P3 test1 = new subP3();
System.out.println(num1);
System.out.println(num2);
test2.add();这段会报错，因为父类P3中没有add方法。

subP3 test2 = new subP3();
System.out.println(num1);
System.out.println(num2);