java - CloneNotSupportedException not thrown on calling clone() method on object that does not implement Cloneable interface -

i started java programming , according java se api documentation, cloneable interface implemented indicate clone operations on class allowed. if not, clonenotsupportedexception thrown. in practice session managed run program cloned class not implement cloneable interface , no exception thrown. need know why exception not thrown. using jdk 6 update 45 , latest eclipse ide on windows 7. following code:

package com.warren.project.first;  public class practiceclass {     //explicit initialisation of practiceclass instance variables    private int fieldone=1;    private int fieldtwo=2;    private int fieldthree=3;     //setters , getters instance fields of practiceclass    public void setfield1(int field1){      this.fieldone=field1;    }     public void setfield2(int field2){      this.fieldtwo=field2;    }     public void setfield3(int field3){      this.fieldthree=field3;    }     public int getfield1(){      return this.fieldone;    }     public int getfield2(){      return this.fieldtwo;    }     public int getfield3(){      return this.fieldthree;    }      //this method clones practiceclass's instances , returns clone    @override    public practiceclass clone(){       practiceclass practiceclass= this;       return practiceclass;    }  }   package com.warren.project.first;  public class appmain {    public static void main(string[] args) {           //create practiceclass object     practiceclass pc1=new practiceclass();      //set instance fields using setters     pc1.setfield1(111);     pc1.setfield2(222);     pc1.setfield3(333);      //display values screen     system.out.println(pc1.getfield1()+" "+pc1.getfield2()+" "+pc1.getfield3());      //create clone of practiceclass object     practiceclass pc2=pc1.clone();      //print values practiceclass clone object     system.out.println(pc2.getfield1()+" "+pc2.getfield2()+" "+pc2.getfield3());   }  } 

this code executes without exception thrown. why isn't clonenotsupportedexception thrown?

in order clonenotsupportedexception thrown, must call super.clone() inside own clone() method. method verify if class implements cloneable