java - JetBrains' @Contract annotation -

-

how org.jetbrains.annotations.contract annotation work? how intellij idea support it?

first off, should annotation idea use check possible errors. java compiler ignore entirely (it'll in compiled artifact have no effect). having said that...

the goal of annotation describe contract method obey, helps idea catch problems in methods may call method. contract in question set of semi-colon separated clauses, each of describes input , output guaranteed happen. cause , effect separated ->, , describe case when provide x method, y always result. input described comma-separated list, describing case of multiple inputs.

possible inputs _ (any value), null, !null (not-null), false , true, , possible outputs adds fail list.

so example, null -> false means that, provided null input, false boolean result. null -> false; !null -> true expands on null always return false , non-null value always return true, etc. finally, null -> fail means method throw exception if pass null value.

for multiple-argument example, null, !null -> fail means that, in two-argument method, if first argument null , second not null, exception thrown, guaranteed.

if method not change state of object, returns new value, should set pure true.


Comments

Post a Comment

Popular posts from this blog

how to insert data php javascript mysql with multiple array session 2 -

-
i have method method discussed , successful data entered 1 when more 1 can not database this programs my php form : <form class="form-horizontal" id="form-produk"> <div class="control-group" > <label class="control-label" for="kelas">kategori</label> <div class="controls"> <select class='form-control' name='id_kategori'> <?php $tampil=mysql_query("select * kategori order nama_kategori"); if ($id_kat==0){ echo "<option value=0 selected>- pilih kategori -</option>"; } while($w=mysql_fetch_array($tampil)){ if ($id_kat==$w[id_kategori]){ echo "<option value=$w[id_kategori] selected>$w[nama_kategori]</option>"; } else{ echo "<option value=$w[id_kategori]>$...
Read more

multithreading - Exception in Application constructor -

-
i wanna write snake game javafx , there exception don't know , want know how fix it. ( know it's not complete yet ) and want know , class extends application ( start override ) main in other programs? see , here not static void main bc didn't need, if want add main shoud do? it's exeption... exception in application constructor exception in thread "main" java.lang.nosuchmethodexception: main_snake.main([ljava.lang.string;) @ java.lang.class.getmethod(class.java:1819) @ com.intellij.rt.execution.application.appmain.main(appmain.java:125) and code : import javafx.animation.animationtimer; import javafx.application.application; import javafx.event.eventhandler; import javafx.scene.scene; import javafx.scene.canvas.canvas; import javafx.scene.canvas.graphicscontext; import javafx.scene.input.keyevent; import javafx.scene.layout.borderpane; import javafx.scene.paint.color; import javafx.stage.stage; import java.util.arraylist; /** * creat...
Read more

windows - CertCreateCertificateContext returns CRYPT_E_ASN1_BADTAG / 8009310b -

-
i realize similar post others (e.g. this one ), there details missing posts might significant case. to start with, here's simplified program: #include "stdafx.h" #include <windows.h> #include <wincrypt.h> int _tmain(int argc, _tchar* argv[]) { // usage: certextract certpath char keyfile[] = "c:\\certificates\\public.crt"; byte lp[65536]; security_attributes sa; handle hkeyfile; dword bytes; pccert_context certcontext; sa.nlength = sizeof(sa); sa.lpsecuritydescriptor = null; sa.binherithandle = false; hkeyfile = createfile(keyfile, generic_read, file_share_read, &sa, open_existing, file_attribute_normal, null); if (hkeyfile) { if (readfile(hkeyfile, lp, getfilesize(hkeyfile, null), &bytes, null) && bytes > 0) { certcontext = certcreatecertificatecontext(x509_asn_encoding, lp, bytes); if (certcontext) { printf("yay...
Read more