分類后的葵花寶典java基礎(chǔ)day11線程

圖上的一鍵優(yōu)化與清除同時在運行，在一個進(jìn)程中同時在執(zhí)行了多個任務(wù)。CPU開銷。線程的使用會給系統(tǒng)帶來上下文切換的額外負(fù)問題：先按照順序運行完了然后接著再按照順序運行完，我們想要的效果是runrun問題：先按照順序運行完了然后接著再按照順序運行完，我們想要的效果是run()JVN不會當(dāng)作線程來運行，會認(rèn)為是普通的方Thread類的對象并啟動該線程，但是如果沒有重寫run()，什么也不線程池中，變得可運行，等待獲取cpu的執(zhí)行權(quán)。阻塞:CPU使用權(quán)，暫時停止運行。直到線程進(jìn)入就緒Thread(Stringname) setName(Stringname) 默認(rèn)線程的優(yōu)先級是5setPriority(intnewPriority)設(shè)置線程的優(yōu)先級 現(xiàn)取決于底層的操作系統(tǒng)的實現(xiàn)（最大的優(yōu)先級是10，最小的1，默認(rèn)是5 sleep(int classThreadDemo1extends{public}publicThreadDemo1(Stringnamesuper(name}publicvoidrun(){inti=0;while(i<30){System.out.println(this.getName()+""+":i="+i);System.out.println(Thread.currentThread().getName()+""+":i="+System.out.println(Thread.currentThread()==this);System.out.println("getId()"+""+":id="+super.getId()System.out.println("getPriority()"+""+":Priority=+super.getPriority()}}}class{publicstaticvoidmain(String[]{ThreadDemo1th1newThreadDemo1("線程1");ThreadDemo1th2newThreadDemo1("線程th1.setName("th1"th2.setName("th2"設(shè)置線程優(yōu)先級1~th1.setPriority(10th2.setPriority(7System.out.println("max:"+Thread.MAX_PRIORITY);System.out.println("min:"+Thread.MIN_PRIORITY);System.out.println("nor:"+Thread.NORM_PRIORITY); o}}都了屬于自己的tickets屬性，那么就總共存在了四份。解決方案一：tickets使用staitc修飾，使每個線程對象都是共份屬性Runnablerun方法packagepackagepublicclassDemo1publicstaticvoidmain(String[]args){MyRunmy=newMyRun();Threadt1=newThread(my);for(inti=0;i<200;i++){System.out.println("main:"+i);}}}classMyRunimplementsRunnablepublicvoidrun()for(inti=0;i<200;i++){System.err.println("MyRun:"+i);}}}執(zhí)行的代碼.RunnableThread的構(gòu)造時,實際上就是讓給Threadrun方法,Thread一項任務(wù).Thread.slee（100classclassMyTicketimplementsRunnableinttickets=publicvoidrun()while(true)if(tickets>0)try}catch(InterruptedExceptione){}System.out.println(Thread.currentThread().getName()tickets號票");}else}}}}publicclassDemo6publicstaticvoidmain(String[]args){MyTicketmt=newMyTicket();Threadt1=newThread(mt);Threadt2=newThread(mt);Threadt3=newThread(mt);Threadt4=newThread(mt);}}每個java對象都有一個鎖對象.而且只有一把類名對象（52T1L1T2L2T1L2T2publicclassDeadLockpublicstaticvoidmain(String[]args)newThread(newRunnable(創(chuàng)建線程publicvoidrun()synchronized("刀叉"){ 你不給我筷子我就不給你刀叉try}catch(InterruptedExceptione){}synchronized("筷子.getName(給你刀叉}}}}, newThread(newRunnable( publicvoidrun()synchronized("筷子"){ 你先給我刀叉我再給你筷子try}catch(InterruptedExceptione){}synchronized("刀叉.getName()+":好吧,把筷子給你}}} 人}}whilenotifyAll喚醒，notify容易出現(xiàn)只喚醒本方線程情況，導(dǎo)致程序中的所有線程都在等待。，publicpublicclassDemo10publicstaticvoidmain(String[]args){p=new Producerpro=newProducer(p);Consumercon=newConsumer(p);Threadt1newThread(pro生產(chǎn)者");Threadt2newThread(con消費者");}} {StringString}classProducerimplementsRunnable{publicProducer()}publicthis.p=}p)publicvoidrun(){inti=0;while(true){if(i%2==publicvoidrun(){inti=0;while(true){if(i%2==0)="jack";p.gender="man";}= p.gender女}}}classConsumerimplementsRunnable{publicConsumer()}publicthis.p=}p)publicvoidrun()while(true)System.out.println("name:"++"---gnder:"}}}Producer和Consumer對象所以Producer和Consumer的是同一個 顯然屏幕輸出了man這樣的結(jié)果是出現(xiàn)了線程安全問題。所以需要使用packagepackagepublicclassDemo10publicstaticvoidmain(String[]args){p=new Producerpro=newProducer(p);Consumercon=newConsumer(p);Threadt1newThread(pro生產(chǎn)者");Threadt2newThread(con消費者");}} {StringString}classProducerimplementsRunnable{publicProducer()}public p)this.p=}publicvoidrun(){inti=0;while(true){synchronized(p)if(i%2==0)="jack";p.gender="man";}= p.gender女}}}}classConsumerimplementsRunnable{publicConsumer()}public p)this.p=}publicvoidrun()while(true)synchronized(p)System.out.println("name:"++"---gnder:"}}}}jack女或者manpublicpublicclassDemo10publicstaticvoidmain(String[]args){p=new Producerpro=newProducer(p);Consumercon=newConsumer(p);Threadt1newThread(pro生產(chǎn)者");Threadt2newThread(con消費者");}} {StringStringpublicsynchronizedvoidset(Stringname,Stringgender)=this.gender=}publicsynchronizedvoidread(){System.out.println("name:"++"----gender:"+}}classProducerimplementsRunnable{publicProducer()}public p)this.p=}publicvoidrun(){inti=0;while(true){if(i%2==0)p.set("jack",}else 女}}}classConsumerimplementsRunnable{publicConsumer()}publicpublicthis.p=}p)publicvoidrun()while(true){}}}有獲得執(zhí)行權(quán)，并持有了相同的監(jiān)視器（鎖）并調(diào)用notify為止。notify：喚醒持有同一個監(jiān)視器（鎖）wait的第一個線程，例如，餐館有空位置packagepackagepublicclassDemo10publicstaticvoidmain(String[]args){p=new Producerpro=newConsumercon=newThreadt1newThread(pro生產(chǎn)者");Threadt2newThread(con消費者");}}//使 Stringname;Stringgender;booleanflag=publicsynchronizedvoidset(Stringname,Stringgender)if(flag)try}catch(InterruptedExceptione)}}=name;this.gender=gender;flag=true;}publicsynchronizedvoidread()if(!flag)try}catch(InterruptedExceptione)}}System.out.println("name:"++"----gender:"flag=false;}}classProducerimplementsRunnable{publicProducer()}public p)this.p=}publicvoidrun(){inti=0;while(true){if(i%2==0)p.set("jack",}else 女}}}classConsumerimplementsRunnable{publicConsumer()}public p)this.p=}publicpublicvoidrun()while(true){}}}waitnotif（，Object類中waitsleep()2.正常終止當(dāng)線程的run()執(zhí)行完畢，線程注意：Stop方法已過時，就不能再使用這個方法。run方法結(jié)束，classclassStopThreadimplementsRunnable{publicbooleantag=true;publicvoidrun()inti=while(tag)"i:"+}}}publicclassDemo8publicstaticvoidmain(String[argsStopThreadst=newStopThread();Threadth=newThread(st,"線程1");for(inti=0;i<100;i++)if(i==50){System.out.println("maini:"+i);st.tag=false;}}}}3.線setDaemon(boolean必須在啟動線程之前（start方法之前）setDaemon（true）方法，才可以把main（）執(zhí)行完畢，那么程序就會終止，JVM也就退出了。該案例：開啟了一個qq檢測升級的線程，通過while真循環(huán)進(jìn)行不停檢測，當(dāng)計數(shù)100的時候，表示檢測完畢，提示是否更新，線程同時結(jié)束。classQQUpdateimplementsRunnableinti=classQQUpdateimplementsRunnableinti=publicvoidrun()while(true)System.out.println(Thread.currentThread().getName()+try}catch(InterruptedExceptione)}if(i==10