Why does this code snippet not have runtime errors as described in the Java tutorials documentation?

public class @R_150_2419@ {

public class @R_150_2419@ {
    private Object object;

    public void set(Object object) { this.object = object; }
    public Object get() { return object; }
}

Referring to the official Java Tutorial documentation and this article in the above code snippet, I try to reproduce runtime errors What's wrong with my code because it doesn't produce any runtime errors?

I wrote the code

public class @R_150_2419@ {
    private Object obj;

    public void set(Object obj) {
        this.obj = obj;
    }
    public Object get() {
        return obj;
    }

    public static void main(String [] args) {
        @R_150_2419@ g = new @R_150_2419@();
        System.out.println(g.get());
        g.set("hello again");
        System.out.println(g.get());
    }
}

Solution

public static void main(String[] args) {

public static void main(String[] args) {
    @R_150_2419@ g = new @R_150_2419@();

    g.set("hello again");
    Integer i = (Integer) g.get();

    System.out.println(i + 1);
}

This code passes in a string, but attempts to retrieve integer The compiler cannot detect this and will fail At runtime, it throws ClassCastException