【文章內(nèi)容簡介】 )。linitialcount：信號(hào)量對(duì)象的初始計(jì)數(shù)值，即可訪問線程數(shù)目的初始值；lmaxcount：信號(hào)量對(duì)象計(jì)數(shù)值的最大值，該參數(shù)決定了同一時(shí)刻可訪問由信號(hào)量保護(hù)的資源的線程最大數(shù)目；后兩個(gè)參數(shù)在同一進(jìn)程中使用一般為null，不作過多討論；在用csemaphore 類的構(gòu)造函數(shù)創(chuàng)建信號(hào)量對(duì)象時(shí)要同時(shí)指出允許的最大資源計(jì)數(shù)和當(dāng)前可用資源計(jì)數(shù)。一般是將當(dāng)前可用資源計(jì)數(shù)設(shè)置為最大資源計(jì)數(shù)，每增加一個(gè)線程對(duì)共享資源的訪問，當(dāng)前可用資源計(jì)數(shù)就會(huì)減1，只要當(dāng)前可用資源計(jì)數(shù)是大于0的，就可以發(fā)出信號(hào)量信號(hào)。但是當(dāng)前可用計(jì)數(shù)減小到0時(shí)，則說明當(dāng)前占用資源的線程數(shù)已經(jīng)達(dá)到了所允許的最大數(shù)目，不能再允許其它線程的進(jìn)入，此時(shí)的信號(hào)量信號(hào)將無法發(fā)出。線程在處理完共享資源后，應(yīng)在離開的同時(shí)通過releasesemaphore()函數(shù)將當(dāng)前可用資源數(shù)加1。例程10 multithread10 為了文件中能夠正確使用同步類，在文件開頭添加： include “” 定義信號(hào)量對(duì)象和一個(gè)字符數(shù)組，為了能夠在不同線程間使用，定義為全局變量：csemaphore semaphorewrite(2,2)。//資源最多訪問線程2個(gè)，當(dāng)前可訪問線程數(shù)2個(gè)在信號(hào)量對(duì)象有信號(hào)的狀態(tài)下，線程執(zhí)行到waitforsingleobject語句處繼續(xù)執(zhí)行，同時(shí)可用線程數(shù)減1；若線程執(zhí)行到waitforsingleobject語句時(shí)信號(hào)量對(duì)象無信號(hào)，線程就在這里等待，直到信號(hào)量對(duì)象有信號(hào)線程才往下執(zhí)行。Java 多線程編程篇二in the following code, which is the earliest statement, where the object originally held in e, may be garbage collected:class test {static void main(string args []){ee e = new employee(“bob”, 48)。atepay()。n(etails())。 = null。 = new employee(“denise”, 36)。atepay()。n(etails())。10.}11.}only one:in the following code, which is the earliest statement, where the object originally held in e, may be garbage collected:class test {static void main(string args []){ee e = new employee(“bob”, 48)。atepay()。n(etails())。 = null。 = new employee(“denise”, 36)。atepay()。n(etails())。10.}11.}only one:1011782:exhibit :class test（e static int j = 0。e static boolean methodb(int k)（ += k。true。6.)static void methoda(int i){n b: = i 10 | methodb(4)。 = i 10 || methodb(8)。12.)static void main(string args[] }（a(0)。n(j)。17.)18.)what is the result?program prints “0”program prints “4”program prints “8”program prints “12”3:what is written to the standard output given the following statement:n(4|7)。select the right answer:4:select valid identifier of java:select valid identifier of java:a.%passwdc.$charge5:設(shè)有變量說明語句int a=1,b=0。則執(zhí)行以下程序段的輸出結(jié)果為()。switch(a){case 1:switch(b){case 0:printf(“**0**”)。break。case 1:printf(“**1**”)。break。}case 2:printf(“**2**”)。break。}printf(“ ”)。a.**0**b.**0****2**c.**0****1****2**6:in the following pieces of code, which one will pile without any error?buffer sb1 = “abcd”。n b = new boolean(“abcd”)。: byte b = 255。fl = 。7:what is the result when you pile and run the following code?public class throwsdemo{static void throwmethod(){n(“inside throwmethod.”)。throw new illegalaccessexception(“demo”)。}public static void main(string args[]){try{throwmethod()。}catch(illegalaccessexception e){n(“caught ” + e)。}}}choices:what is the result when you pile and run the following code?public class throwsdemo{static void throwmethod(){n(“inside throwmethod.”)。throw new illegalaccessexception(“demo”)。}public static void main(string args[]){try{throwmethod()。}catch(illegalaccessexception e){n(“caught ” + e)。}}}choices:ation errore errore successfully, nothing is ed by caught:laccessexcption: demo8:which of the following statements are not legal?l = 4990。i = 4l。d = 。t = :give the following java class:public class example{public static void main(string args[]){static int x[] = new int[15]。n(x[5])。}}which statement is corrected?give the following java class:public class example{public static void main(string args[]){static int x[] = new int[15]。n(x[5])。}}which statement is corrected?pile, some error will run, some error will is is :下面關(guān)于變量及其范圍的陳述哪些是錯(cuò)的。11:public class x{public object m(){object o = new float()。//line 3object [] oa = new object[1]。//line 4oa[0] = o。//line 5o=null。//line 6return oa[0]。//line 7}}when is the float object, created in line 3,eligible for garbage collection?public class x{public object m(){object o = new float()。//line 3object [] oa = new object[1]。//line 4oa[0] = o。//line 5o=null。//line 6return oa[0]。//line 7}}when is the float object, created in line 3,eligible for garbage collection?after line after line 6after line 7(that is,as the method returns)in this method12:which is the most appropriate code snippet that can be inserted at line 18 in the following code?(assume that the code is piled and run with assertions enabled).*。class asserttest4.{e hashmap cctld。asserttest()8.{= new hashmap()。(“in”, “india”)。(“uk”, “united kingdom”)。(“au”, “australia”)。13.// more code...14.}15.// other methods.... string getcountry(string countrycode)17.{18.// what should be inserted here?country =(string)(countrycode)。country。21.}22.}which is the most appropriate code snippet that can be inserted at line 18 in the following code?(assume that the code is piled and run with assertions enabled).*。class asserttest4.{e hashmap cctld。asserttest()8.{= new hashmap()。(“in”, “india”)。(“uk”, “united kingdom”)。(“au”, “australia”)。13.// more code...14.}15.// other methods.... string getcountry(string countrycode)17.{18.// what should be inserted here?country =(string)(countrycode)。country。21.}22.}countrycode!= null。countrycode!= null : “country code can not be null”。cctld!= null : “no country code data is available”。cctld : “no country code data is available”。13:give the following code:public class example{public static void main(string args[]){int l=0。do{n(“doing it for l is:”+l)。}while(—l0)n(“finish”)。}}which well be output:give the following code:public class example{public static void main(string args[]){int l=0。do{n(“doing it for l is:”+l)。}while(—l0)n(“finish”)。}}which well be output:it for l is 3it for l is 1it for l is 2it for l is 014:which statements about java code security are not true?bytecode verifier loads all classes needed for the execution of a ing code is performed by the runtime runtime the bytecodes are loaded, checked and run in an interpreter. class loader