Java中Vehicle类作父类含引擎与轮数属性及运行停止方法，Car和Truck子类各有特有属性及方法
oad（num:int）:void。
Vehicle类的代码如下：
```java
public class Vehicle {
private String engine;
private int wheelNum;
public Vehicle(String engine, int wheelNum) {
this.engine = engine;
this.wheelNum = wheelNum;
}
public void run() {
System.out.println("Vehicle is running.");
}
public void stop() {
System.out.println("Vehicle has stopped.");
}
}
```
Car类的代码如下：
```java
public class Car extends Vehicle {
private boolean openable;
public Car(String engine, int wheelNum, boolean openable) {
super(engine, wheelNum);
this.openable = openable;
}
public void getIn(int num) {
System.out.println(num + " people get in the car.");
}
public void getOut(int num) {
System.out.println(num + " people get out of the car.");
}
}
```
Truck类的代码如下：
```java
public class Truck extends Vehicle {
private int capacity;
public Truck(String engine, int wheelNum, int capacity) {
super(engine, wheelNum);
this.capacity = capacity;
}
public void load(int num) {
System.out.println("Load " + num + " goods.");
}
public void unload(int num) {
System.out.println("Unload " + num + " goods.");
}
}
```
以上是基于题目提供的要求编写的代码，其中Vehicle类作为父类，Car和Truck类作为子类，分别继承了Vehicle类的属性和方法，并且在子类中添加了自己的属性和方法。在Car类中添加了openable属性和getIn、getOut方法，在Truck类中添加了capacity属性和load、unload方法。
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