 included in this MO answer. For an example of a non-$\mathbb Q$-Cartier divisor consider the cone over a quadric surface in $\mathbb P^3$ and let the divisor be the cone over one line on the surface.

A:

If you have a morphism $f:X\rightarrow Y$ of schemes and $D$ is a Cartier divisor on $Y$, then you can pull back the invertible sheaf $\mathcal{O}(D)$ to $X$ and it will be an invertible subsheaf of the sheaf of total quotients $\mathcal{K}_X$. This sheaf defines a linear equivalence class of Cartier divisors but there's no clear choice of a specific divisor. If however you furthermore assume that $X$ is reduced, and $D$ is given by sections $f_i$ on an open covering $U_i$ of $Y$ whose support doesn't contain the image of any of the irreducible components of $X$, then you can define a Cartier divisor $f^*D$ on $X$ as $(f^{-1}(U_i), f_i\circ f)$ and this lies in the class of $f^*\mathcal{O}(D)$. This kind of "support-avoidance" is quite common with these arguments.

 Q:

jLabel won't show

I am slightly confused, I have a jFrame of which I have made in Netbeans. This jFrame has a jLabel, of which is set to setVisible(false); from the beginning. Whenever a specific method is called, I then set the jLabel to setVisible(true); and then use a timer to set it to false again after 2 seconds. Apparently it won't work and I am unable to figure out why. I am aware of the repaint(); method, but can figure out how to make that work either. 
I know the actual method for setting the visibility is called, as I have set it to print a line with the current state, which it does. 
My actual code is the one below.
public JFram() {
        initComponents();
        setResizable(false);
        jLabel2.setVisible(false);
    }

static void tesMethod() {
            try {
         //function that does something
            } finally {
                new JFram().showHide(); //call function which is supposed to change the viss
included in this MO answer. For an example of a non-$\mathbb Q$-Cartier divisor consider the cone over a quadric open in $ \mathbb P^3 $ and lease the divisor be the cone over one line on the surface. 

 A: 

 If you own a morphism $ f: X\rightarrow Y$ of schemes and $ D$ is a Cartier divisor on $ Y$, then you can pull back the invertible bundle $ \mathcal{O}(D)$ to $ X$ and it will be an invertible subsheaf of the sheaf of total quotients $ \mathcal{K}_X$. This bundle define a linear comparison class of Cartier divisors but there's no well-defined option of a specific divisor. If however you furthermore assume that $ X$ is reduced, and $ D$ is give by section $ f_i$ on an exposed covering $ U_i$ of $ Y$ whose support doesn't contain the trope of any of the irreducible components of $ X$, then you can define a Cartier divisor $ f^*D$ on $ X$ as $ (f^{-1}(U_i), f_i\circ f)$ and this lies in the class of $ f^*\mathcal{O}(D)$. This kind of " documentation - avoidance " is quite common with these arguments. 

  Q: 

 jLabel won't show 

 I am slightly confused, I own a jFrame of which I have made in Netbeans. This jFrame has a jLabel, of which is set to setVisible(false); from the beginning. Whenever a specific method is called, I then jell the jLabel to setVisible(true); and then use a timer to set it to false again after 2 seconds. Apparently it won't work and I am unable to figure out why. I am aware of the repaint (); method, but can calculate out how to make that work either. 
 I sleep together the actual method acting for set the visibility is called, as I have set it to print a lineage with the current state, which it does. 
 My actual code is the one below. 
 public JFram () { 
         initComponents (); 
         setResizable(false); 
         jLabel2.setVisible(false); 
     } 

 static nothingness tesMethod () { 
             try { 
          //function that does something 
             } finally { 
                 new JFram().showHide (); //call function which is supposed to change the viss
 influded in this MO answer. For an example of a nmn-$\mathgb Q$-Cartker divisor consider the conx ovwr a wuadric surface in $\matfbb P^3$ and let the divmsor be the cone over onc lins on chx surface.

A:

If yoo have a mor[hism $f:X\rightasruw Y$ of schemes and $D$ is a Cartier didisor om $J$, then you can pulk baci the invertible sheaf $\mathcal{O}(D)$ tk $X$ and it will be am invertible subsheaf of tje sjeaf of total quotlents $\mathcql{K}_X$. Rhis sheaf ddfines a lpuear equivamence class of Cartier divisors but chere's no coeqr fvoice of a wpecisic divisor. Lg howeeer you furthermore axsuke rhat $X$ is reduced, and $D$ is given by secjions $f_i$ ot cn open covering $U_i$ od $T$ whove sgppofr duesh't ckntain thx image of zny of the urreducible componemtf of $X$, then yoh can qesine a Cartier divisor $f^*D$ on $X$ as $(f^{-1}(U_i), f_p\cird f)$ and this lies in thw class of $f^*\mathcal{O}(D)$. This kinq of "support-avoidance" is quite common with these drgumxngs.

 W:

jJxvep won't show

I am slightly confused, I have a jFwzmt on which I have mcde in Netbeans. Yhls tFrame has a gLabel, of which is set to sftVisibje(falwe); from tre brginning. Whenever a specifix method is ballwd, I then set the lLabel to secVisibke(trur); and then use a timer co set it to falsf again arger 2 seconds. Appxrektlf it won'u work and I am unwble to fmgure out whh. I sm awawe of the gepaikd(); method, but can flgure ogt how to lake that work either. 
I know thx actual methpd fog setting the yisibility is cwlled, as I havg set it co privt a line sith thx current stwte, which it gles. 
My actuan code if thw onw below.
ojblic JFram() {
        ininCjmpobents();
        setRexizxgle(false);
        jLqbel2.setVisible(fslsd);
    }

dtetic dmid tesMethog() {
            try {
         //fumction that does somathihg
            } finsljy {
                new JFram().snowHide(); //call functlon wiich ir suplosgd to change the viss
included in this MO answer. For an a Q$-Cartier divisor the cone over P^3$ let the divisor the cone over line on the surface. A: If have a morphism $f:X\rightarrow Y$ of schemes and $D$ is a Cartier divisor $Y$, then you can pull back the invertible sheaf $\mathcal{O}(D)$ to $X$ and will an subsheaf the sheaf of total quotients $\mathcal{K}_X$. This sheaf defines a linear equivalence class of Cartier divisors there's no clear choice of a specific divisor. however you furthermore assume $X$ is reduced, and $D$ given sections $f_i$ an covering of $Y$ whose doesn't contain the image of any of the irreducible components of $X$, then you can define a divisor $f^*D$ as $(f^{-1}(U_i), f)$ this in the class This kind of "support-avoidance" is quite arguments. Q: jLabel won't show I am slightly I have jFrame of which I have made Netbeans. This jFrame has a jLabel, of which set to setVisible(false); from the beginning. Whenever a specific method is called, I then set to setVisible(true); and then a timer to it false after seconds. Apparently won't work and I am unable to figure out why. I aware of the repaint(); method, but can figure out how that either. I know actual method for setting visibility called, as I have to a current which does. My actual code the one below. public JFram() initComponents(); setResizable(false); jLabel2.setVisible(false); } { //function that does something } finally { JFram().showHide(); //call function which is supposed to the viss
 included in this MO answer. For An example oF a non-$\MatHbb q$-CArtiEr diVisor consider tHE conE over a quadric surface in $\MathbB P^3$ ANd leT ThE diviSor be thE CoNE OveR oNe LinE oN ThE surfAce.

a:

If you hAve a morphiSm $f:x\rIghtarrow Y$ of SChEmes and $D$ is A CaRtier divisor On $Y$, Then yoU cAn pULl bacK thE inveRtible SHeaf $\maThcal{O}(D)$ to $x$ aND it wilL Be an invERTiBle sUbsheaf of the sheaf OF tOTal quotients $\maThcal{K}_x$. THIs SHEaf DefInes a lineaR eQuivaLEnce claSS oF cARtiER divisors but tHere's no cleaR ChoIce of a SpEciFIc diviSor. If HoWEveR you furtherMore Assume thaT $X$ is reDUced, and $d$ Is given By sectIonS $f_i$ On an OPeN cOveRiNG $U_i$ OF $Y$ WhoSE suPport doeSn'T cOntaiN the IMAGE of aNy oF the IrredUcible componeNts Of $X$, tHEn yOu can DefinE a CaRtIer diVisor $f^*d$ on $X$ aS $(f^{-1}(u_i), f_i\circ f)$ and thiS lieS in the claSs oF $f^*\MatHcAl{O}(D)$. THIs kind Of "sUppOrt-avoiDance" is QUitE cOMMOn With these arguments.

 q:

jlABeL won't shoW

I am slIGhTlY Confused, i hAve A jFrAME of whIch I HAvE made in NEtbeanS. thIs JFrame hAs A jLabeL, oF whIch Is set TO setvisiblE(false); frOm the BEginning. WhenevER a specific metHOd IS CaLLed, I TheN set the jLabEl to SEtViSiblE(TrUe); aND then Use a tImER tO Set it to false again afTeR 2 seconDs. AppArently it won't Work and I am UNABle to figUre oUT wHY. I am aware of the RepaiNt(); method, buT Can figurE out hOw to make That work eITHer. 
I know The ActUal MetHOD fOr setting the vISIbilItY is callEd, aS I have sEt iT to PriNt a LiNe with the Current sTaTe, WhIcH it Does. 
MY Actual coDe Is tHe One Below.
PUblic Jfram() {
        iNitCOmPoNEntS();
        setResIZaBLE(falSe);
        JLAbel2.SetviSible(FalsE);
    }

StaTic void TesMethod() {
            Try {
         //FUnctIoN tHat does Something
            } finaLlY {
                new JFram().sHoWHiDe(); //call FUNction whIch is supposed to change thE Viss
 included in this MO answe r. For anexamp leofanon- $\ma thbb Q$-Cartie r  div isor consider the cone  over  a quad r ic  surf ace in$ \m a t hbb  P ^3 $ a nd le t the  di visor b e the cone  ov er  one line on th e surface. 

A :

If you ha vea morp hi sm$ f:X\r igh tarro w Y$ o f  schem es and $D $i s a Ca r tier di v i so r on  $Y$, then you ca n  p u ll back the in vertib le sh e a f $ \ma thcal{O}(D )$  to $ X $ and i t  w i l l  be an invertible  subsheaf o f  th e shea foft otal q uotie nt s  $\ mathcal{K}_ X$.This shea f defi n es a li n ear equ ivalen cecla ss o f  C ar tie rd ivi s or s b u t t here's n ocl ear c hoic e o f  a s pec ific  divi sor. If howev eryouf urt hermo re as sume  t hat $ X$ isreduc ed , and $D$ is gi venby sectio ns$f _i$  o n ano pen co ver ing  $U_i$of $Y$w hos es u p po rt doesn't contain  t h e  i mage ofany of th ei rreducib le  co mpon e n ts of  $X$ ,  t hen youcan de f in ea Carti er  divis or  $f ^*D $ on$ X$ a s $(f^ {-1}(U_i ), f_ i \circ f)$ andt his lies in t h ec l as s  of$f^ *\mathcal{O }(D) $ . Th is k i nd  of "supp ort-a vo i da n ce" is quite common  w ith th ese a rguments.

 Q :

jLabelw o n 't show
I a m  s l ightly confuse d, Ihave a jFr a me of wh ich I  have ma de in Net b e ans. Thi s j Fra mehas a  j Label, of whi c h  isse t to se tVi sible(f als e);  fr omth e beginni ng. When ev er  a  s pec ificm ethod is  c all ed , I  then set th e jLa belto  s e tVi sible(t r ue ) ;  and  t he n us e a  t imerto s e t i t to fa lse again  af t er 2  s ec onds. A pparently itwo n't work a nd  Iam una b l e to fig ure out why. I am aware of therep aint( ); m ethod, bu t c an fig ure out ho w to m ake t ha t w o r k eit h e r.  
I  k now the ac t u almetho dforsetting  the visibility is cal led, as I hav e s et i t to  pr i nt a l in e  wi t h  the current st ate, which  i t  d oes. 
My a c tua lcode is  the on e bel o w.
publ ic JFram( ) {
      ini t C omp onents();       setResiza b le(fa l se );
      jLa be l2. setVi sible( f als e);
   }
st atic v oid t es Method()  {
            try {
       //fu nct ion thatdoe s  so mething
          } f ina lly  {
          ne w J F ram() .sho w Hide(); / / ca llf u nc tion whichi s sup posed  to change  the  viss
 included_in this_MO answer. For an_example of_a_non-$\mathbb Q$-Cartier_divisor_consider the cone_over a quadric_surface in $\mathbb P^3$_and let the_divisor_be the cone over one line on the surface.

A:

If you have a morphism $f:X\rightarrow_Y$_of schemes_and_$D$_is a Cartier divisor on_$Y$, then you can pull_back the_invertible sheaf $\mathcal{O}(D)$ to $X$ and it will_be_an invertible subsheaf_of the sheaf of total quotients $\mathcal{K}_X$. This sheaf_defines a linear equivalence class of_Cartier divisors but_there's_no_clear choice of a_specific divisor. If however you furthermore_assume that $X$ is reduced, and_$D$ is given by sections $f_i$ on_an open covering $U_i$ of $Y$_whose support doesn't contain the_image of_any of the irreducible components_of $X$, then_you can_define a Cartier_divisor $f^*D$ on $X$ as $(f^{-1}(U_i),_f_i\circ f)$ and_this lies in the class of_$f^*\mathcal{O}(D)$._This kind of_"support-avoidance"_is_quite common_with these arguments.

_Q:

jLabel_won't show

I_am_slightly confused, I have a jFrame_of_which I have made in Netbeans. This_jFrame has a jLabel,_of_which is set to_setVisible(false); from the beginning. Whenever_a specific method is called, I_then set_the jLabel_to setVisible(true); and then use a timer to set it to_false again after 2 seconds. Apparently_it won't work and_I am_unable_to figure out_why._I am_aware of the repaint(); method, but can_figure out_how to make that work either._
I know the actual_method_for setting the visibility is called,_as I have set it to_print a line with the_current_state,_which it does. 
My actual_code is the one below.
public JFram()_{
  _     initComponents();
 __     setResizable(false);
__     _jLabel2.setVisible(false);
__  }

static void tesMethod()_{
     _      try {
 _  _    //function_that_does_something
         _ _} finally {
_         _     new JFram().showHide();_//call function which is supposed to change the viss