Java 10 中原始类型的通用类型？

Question

How do you convert generic type "t" to Integer in the following code?

Is ( Integer.parseInt(String.valueOf(t) ) better than explicit cast (Integer)t ?

Has Java 10 got it?

import java.lang.System;

class A {
    public void setString(String s) {
        s += ", World!";
        System.out.println ("setString:" + s);
    }

    public void setInt(Integer i) {
        i *= 100;
        System.out.println ("setInt:" + i);
    }
    
    public <T> void Method(T t)
    {    if (t.getClass().getName() == "java.lang.String")  {
             setString(String.valueOf(t));
         }
         else if(t.getClass().getName() == "java.lang.Integer") {
            setInt (Integer.parseInt(String.valueOf(t) ));
         }
         System.out.println (t.getClass().getName());
    }
}

Answer 1

Is (Integer.parseInt(String.valueOf(t)) better than explicit cast (Integer)t 

No. This is unnecessarilly complex and the cast is the way to go (this line converts the Integer to a String, and then the String to an int. This has no advantages over just casting to Integer).

Additionnally, to operator instanceof is much better than using getClass().getName()

Answer 2

Your approach with converting values looks like this:

  Integet t = 2;
  Integer newValue = Integer.parseInt(String.valueOf(t));

So it goes as : Integer > String > Integer.

As proposed by @andy-turner checking by instanceOf is simpler. If your class is of type X, then you can do a simple casting, without any additional methods.

Secondly code looks much cleaner:

  public <T> void method(T t) {
        if (t instanceof String) {
            setString((String) t); // t is an String
        } else if (t instanceof Integer) {
            setInt((Integer) t); // t is an Integer
        }
        System.out.println(t.getClass().getName());
    }