JAVA程序执行内存分析.ppt

JAVA程序执行内存分析,内存分析,内存中的存放,codesegment,datasegment,stack,heap,存放代码,静态变量，字符串变量,局部变量,new出来的东西,Birthdate类,classBirthDateprivateintday;privateintmonth;privateintyear;publicBirthDate(intd,intm,inty)day=d;month=m;year=y;publicvoidsetDay(intd)day=d;publicvoidsetMonth(intm)month=m;publicvoidsetYear(inty)year=y;publicintgetDay()returnday;publicintgetMonth()returnmonth;publicintgetYear()returnyear;publicvoiddispaly()System.out.println(day+-+month+-+year);,Test类,publicclassTestpublicstaticvoidmain(Stringargs)Testtest=newTest();intdate=9;BirthDated1=newBirthDate(7,7,1970);BirthDated2=newBirthDate(1,1,2000);test.change1(date);test.change2(d1);test.chang3(d2);System.out.println(date=+date);d1.display();d2.display();publicvoidchang1(inti)i=1234;publicvoidchang2(BirthDateb)b=newBirthDate(22,2,2004);publicvoidchang3(BirthDateb)b.setDay(22);,内存中变量存放说明,Testtest=newTest();test为局部变量，指向new出来的对象,test:xxx,stack,heap,内存中变量存放说明,intdate;定义局部变量，占一块内存,stack,date:9,内存中变量存放说明,BirthDated1=newBirthDate(7,7,1970);局部变量d1，指向new出来的对象,stack,d1:xxx,y1970,m7,d7,heap,day,month,year,构造方法调用结束后，d,m,y将被释放,内存中变量存放说明,test.change1(date);调用Test中的change1方法,stack,date:9,i,i:9,i:1234,传值,赋值,调用结束，i被释放,内存中变量存放说明,test.change2(d1);,heap,stack,d1:xxx,b:xxx,day:7,month:7,year:1970,传地址,new:xxx,day:22,month:2,year:2004,传地址,1,2,3,4,5,6,方法调用结束后b和new消失,7,内存中变量存放说明,test.chang3(d2);,stack,heap,d2:xxx,b:xxx,day:1,month:1,year:2000,d:22,1,3,2,4,传值,传值,方法调用结束后b和d消失,5,三维坐标中的点,classPointintx,y,z;Point(inta,intb,intc)x=a;y=b;z=c;voidgetDistance(Pointp)return(x-p.x)*(x-p.x)+(y-p.y)*(y-p.y)+(z-p.z)*(z-p.z);Pointp1=newPoint(1,2,3);System.out.println(+getDistance(newPoint(0,0,0);,上例内存分析,System.out.println(+getDistance(newPoint(0,0,0);,stack,heap,x:1,y:2,z:3,x:0,y:0,z:0,p1:xxx,p:xxx,1,3,2,传地址,调用结束后p被释放,this关键字的引用,publicclassLeafinti=0;Leaf(inti)this.i=i;Leafincreament()i+;returnthis;voidprint()System.out.println(i=+i);publicstaticvoidmain(Stringargs)Leafleaf=newLeaf(100);leaf.increament().increament().print();,this关键字的引用,Leafleaf=newLeaf(100);,stack,heap,this,i:100,i:100,调用结束后i被释放,leaf：xxx,想象this在类中,this关键字的引用,leaf.increament().increament().print();,leaf:xxx,this,i:102,leaf1:xxx,leaf2:xxx,this是当前对象的引用,stack,heap,this关键字的引用,leaf.increament().increament().print();相当于以下程序段：leaf.increament();leaf.increament();leaf.print();leaf.increament().increament().print();,返回leaf对象的引用l1，指向leaf对象,返回leaf对象的引用l2，指向leaf对象,内存分析（一）,classPointXY/分析程序在内存中执行过程privatedoublex;privatedoubley;PointXY(doublex1,doubley1)x=x1;y=y1;publicdoublegetX()returnx;publicdoublegetY()returny;publicvoidsetX(doublei)x=i;publicvoidsetY(doublei)y=i;,内存分析（二）,classCircleprivatePointXYo;privatedoubleradius;Circle(PointXYp,doubler)o=p;radius=r;Circle(doubler)o=newPointXY(0.0,0.0);radius=r;booleancontains(PointXYp)doublex=p.getX()-o.getX();doubley=p.getY()-o.getY();if(x*x+y*yradius*radius)returnfalse;elsereturntrue;publicvoidsetO(doublex,doubley)o.setX(x);o.setY(y);publicPointXYgetO()returno;publicdoublegetRadius()returnradius;publicvoidsetRadius(doubler)radius=r;publicdoublearea()return3.14*radius*radius;,内存分析（三）,publicclassTestCirclepublicstaticvoidmain(Stringargs)Circlec1=newCircle(newPointXY(1.0,2.0),2.0);Circlec2=newCircle(5.0);System.out.println(c1:(+c1.getO().getX()+,+c1.getO().getY()+),+c1.getRadius();System.out.println(c2:(+c2.getO().getX()+,+c2.getO().getY()+),+c1.getRadius();System.out.println(c1area=+c1.area();System.out.println(c2area=+c2.area();c1.setO(5,6);c2.setRadius(9.0);System.out.println(c1=(+c1.getO().getX()+,+c1.getO().getY()+),+c1.getRadius();System.out.println(c2=(+c1.getO().getX()+,+c2.getO().getY()+),+c2.getRadius();System.out.println(c1area=+c1.area();System.out.println(c2area=+c2.area();PointXYp1=newPointXY(5.2,6.3);System.out.println(c1.contains(p1);System.out.println(c1.contains(newPointXY(10.0,9.0);,Circlec1=newCircle(newPointXY(1.0,2.0),2.0);,c1:xxx,x:1.0,y:2.0,x1:1.0,y1:2.0,o,radius:2.0,p:xxx,r:2.0,紫色的调用结束后释放,红色的几位调用结束后内存布局,stack,heap,Circlec2=newCircle(5.0);,c2:xxx,o,radius:5.0,r:5.0,x1:0.0,y1:0.0,x:0.0,y:o.o,stack,heap,System.out.println(c1:(+c1.getO().getX()+,+c1.getO().getY()+),+c1.getRadius();,c1:xxx,o,radius:2.0,x:1.0,y:2.0,和o里的值一样,1.0,返回值,返回值,stack,heap,2.0,返回值,c1.setO(5,6);c2.setRadius(9.0);,o,radius:2.0,o,radius:5.09.0,x:1.05,y:2.06,x:0.0,y:0.0,c1:xxx,c2:xxx,x:5,y:6,i:5,i:6,r:9.0,heap,stack,System.out.println(c1.contains(p1);,o,radius:2.0,x:5,y:6,x:5.2,y:6.3,c1:xxx,p1:xxx,p:xxx,x,y,stack,heap,true,static关键字的使用,publicclassCatprivatestaticintsid=0;privateStringname;intid;Cat(Stringname)=name;id=sid+;publicvoidinfoSystem.out.println(Mynameis+name+NO.+id);publicstaticvoidmain(Stringargs)Cat.sid=100;Cat.mimi=newCat(mimi);Cat.pipi=newCat(pipi);();();,static关键字的使用,stack,heap,dataseg,sid:100101102,id:100,name,id:101,name,mimi:xxx,pipi:xxx,mimi,pipi,name,name,类的继承,student,Person,name,age,school,stack,heap,子类,父类,Java权限修饰符,super和this的使用,cc:xxx,valeu,value,this,super,子类,父类,Testsupr.classStus1=newStu(C,s1);,pers,name,location,school,this,super,heap,beijing,C,s1,s1,name,school,n,l,school,name,location,dataseg,stack,hashcodestable,hashcodestable,对象,对象,对象,对象,对象,每一个对象都有独一无二的hashcodes,通过它可以找到所在对象的位置,对象转型casting(TestAnimals),classAnimalclassDgextendsAnimalAnimala=newAnimal();/a=newDg();/Dgd1=(Dg)a;/,对象转型casting(TestAnimals),Animala,Animal,name,furcolor,程序中把a当成一只普通的Animal，不能访问Dg中的成员,Dg,不能访问,表明,实质,只能访问作为父类的那部分成员,Dgd1,动态绑定和多态(TestPolymoph),Catec,name:catname,eyeColor:blue,name:l1,Animapet,ladyl1,实质上指向,codeseg,Animaenjoy,Cateenjoy,Doenjoy,根据实际对象类型来调用,方法,星际的多态应用,父类GameObject,draw(),继承,使用多态,异常的概念,publicvoidsomeMethod()throwsSomeExceptionif(someCondition()thrownewSomeException(错误原因);,声明该方法可能抛出的异常,构造并抛出异常对象,抛出异常,trysomeMethod();catch(SomeExceptione)/异常处理代码；,调用该方法时试图捕捉异常,定义处理异常的代码,异常的分类,Throwable,Error,Exception,RuntimeException,可抛出的,系统错误，处理不了,能处理的错误,经常出的错误，可以不catch,必须得catch的异常,运行时异常,非运行时异常,method()throwsSomeException.,包含,异常类的父类,异常的捕获和处理,try/可能抛出异常的语catch(SomeExceptione1).catch(SomeExceptione2).finally.,统一的出口，都要被执行，可进行资源的清除工作,readFile()throwsIOException.method1()throwsIOExceptionreadFile()method2()throwsIOExceptionmethod1()publicstaticmain(Strings)trymethod2()catch(IOExceptione).,抛异常,抛异常,抛异常,捕获,处理,main方法可不处理，向外抛,ints;数组定义s=newint5;,xxx,s,stack,heap,自动初始化都为0,Datedays;数组分配空间和赋值days=newDate3;for(inti=0;i3;i+)daysi=newDate(2004,4,i+1);,xxx,xxx,xxx,xxx,2004,4,1,2004,4,2,2004,4,3,days,stack,heap,数组动态初始化,inta;/定义a=newint3;/分配空间a0=1;a1=2;a2=3;/赋值Datedays;/定义days=newDate2;/分配空间days0=newDate(2004,4,1);/赋值days1=newDate(2004,4,2);/赋值,数组定义与为数组元素分配空间和赋值分开进行,数组元素静态初始化,inta3=1,2,3;Datedays=newDate(2004,4,1),newDate(2004,4,2),newDate(2004,4,3);,在定义数组的同时就分配空间和赋值,数组元素的默认初始化,数组是引用类型，它的元素相当于类的成员变量，因此数组分配空间后，每个元素也被按照成员变量的规则被隐式初始化,inta=newint3;System.out.println(a1);Datedays=newDate3;System.out.prinyln(days2);,数组作为返回值,.,Dated,xxxx,返回值,数组模拟链表,1,2,3,4,0,5,0,1,5,4,3,2,3,4,5,0,2,0,2,3,4,5,删除该元素,二维数组,xxxx,a0,a2,a00,a01,a10,a11,a20,a21,.,.,.,heap,stack,a1,xxxx,xxxx,xxxx,a,一维数组,数组的数组,Java中多维数组的声明和初始化应按从高维到低维的顺序进行,inta=newint3;/动态初始化a0=newint2;a1=newint4;a2=newint3;inta=newint35;/动态初始化inta=4,2,13,32,424,32,1,32,12;/静态初始化二维数组的访问：aij,二维数组的输出,inta=1,2,3,4,5,6,7,8,9;for(inti=0;i,List,Map,HashSet,LinkedList,ArrayList,HashMap,无顺序，不可重复,有顺序，可重复(equals),一个一个向里装,一对一对向里装,Iterator容器,next,元素,游标,Array与Linked比较,去掉,Array,Linked,改时要建一个新的数组,读时沿着链表向下查找,InputStream流,PipedInputStream,FilterInputStream,ByteArrayInputStream,SequenceInputStrea