java.lang.NullPointerException: Cannot invoke "Humen.humen.hoHome()" because "zhangsan" is null为啥出现这个问题
Humen;
com.example.demo2.Car.Car;
ZhangSan HumenWithCar{
(Car car){
(car);
}
(){
.start();
.turnLeft();
.turnRight();
.stop();
}
}Humen;
com.example.demo2.Car.Car;
LiSi HumenWithCar{
(Car car){
(car);
}
(){
.start();
.turnRight();
.stop();
}
}com.example.demo2.Car;
java.lang.reflect.Constructor;
java.lang.reflect.InvocationTargetException;
java.util.Map;
java.util.concurrent.ConcurrentHashMap;
IoCContainer {
Map<String, Object> = ConcurrentHashMap<String, Object>();
Object (String beanId) {
.get(beanId);
}
(Class<?> clazz, String beanId, String ...paramBeanIds) {
Object[] paramValues = Object[paramBeanIds.];
(i = ; i < paramBeanIds.; i++) {
paramValues[i] = .get(paramBeanIds[i]);
}
Object bean = ;
(Constructor<?> constructor : clazz.getConstructors()) {
{
bean = constructor.newInstance(paramValues);
} (InstantiationException | InvocationTargetException | IllegalAccessException e) {
}
}
(bean==) {
RuntimeException();
}
.put(beanId, bean);
}
}com.example.demo2;
Humen.LiSi;
Humen.ZhangSan;
Humen.humen;
com.example.demo2.Car.Audi;
com.example.demo2.Car.Buick;
com.example.demo2.Car.IoCContainer;
org.junit.;
org.junit.jupiter.api.;
Demo2ApplicationTests {
IoCContainer = IoCContainer();
(){
.setBeans(Audi., );
.setBeans(Buick., );
.setBeans(ZhangSan., ,);
.setBeans(LiSi., ,);
}
() {
humen zhangsan = (humen) .getBean();
zhangsan.hoHome();
humen lisi = (humen) .getBean();
lisi.hoHome();
}
}java.lang.NullPointerException: Cannot invoke "Humen.humen.hoHome()" because "zhangsan" is null
