Java down casting

Java down casting


public class TInq extends Inq {

    private String tsyInq;

    public String getTsyInq() {
        return tsyInq;
    }

    public void setTsyInq(String tsyInq) {
        this.tsyInq = tsyInq;
    }

}


public class Test {
    public static void main(String[] args) {

        Inq inq = new Inq();
        inq.setId("123");

        inq = new TInq();
        TInq tinq = (TInq) inq;
    }

}
This works because supercalss (Inq) is infact holding refrence to sub class. If i remove highligted line then one would get cast class exceptions.