如何将null转换为Throwable super（（Throwable）null）;(how can null be casted to Throwable super((Throwable)null); [duplicate])

 
 
 这个问题在这里已有答案： 
 
 
 
  
 在java 9中 使用null进行类型转换时没有异常 
 
 
 
 
 这个问题只是让我理解这个概念。 如何将null转换为（Throwable）？ null不是一个类吧？ 这个问题很可愚蠢。 
 
 我知道： 
 
public class SuperClass{
    int id = 0;
    public SuperClass(int id){
        this.id = id;
    }
}

public class SubClass extends SuperClass{
    public SubClass(int id) {
        super(id);
    }       
}

public class Tester{
    SubClass sub = new SubClass(1);
    SuperClass s = new SuperClass(2);
    SuperClass s1 = new SubClass(3);

    public Tester(){
        if(s1 instanceof SubClass){
            //true
            SubClass subClass = (SubClass) s1;
        }
    }       
}`

 
 
This question already has an answer here:
 
 
 
  
 No Exception while type casting with a null in java  10 answers  
 
 
 
 
This question is just for me to understand this concept. How can null be casted to (Throwable)? null is not a class right? This question is propably stupid.
 
I know that:
 
public class SuperClass{
    int id = 0;
    public SuperClass(int id){
        this.id = id;
    }
}

public class SubClass extends SuperClass{
    public SubClass(int id) {
        super(id);
    }       
}

public class Tester{
    SubClass sub = new SubClass(1);
    SuperClass s = new SuperClass(2);
    SuperClass s1 = new SubClass(3);

    public Tester(){
        if(s1 instanceof SubClass){
            //true
            SubClass subClass = (SubClass) s1;
        }
    }       
}`

原文：https://stackoverflow.com/questions/36591777