数组与字符串(基础篇).ppt

第六章数组与字符串,6.1数组6.2字符串,6.1数组,数组的创建(一维数组和二维数组；基本数据类型和复合数据类型）指定数组名称、数据类型typevar_name;如：chars;Objecto;inti;,6.1数组,为数组分配内存空间var_name=newtypesize;如：s=newchar30;o=newObject2;o0=newObject();o1=newObject();i=newint23;chars=newchar30;初始化inti1=1,1,2,3,6.1数组,数组的使用(一维数组和二维数组；基本数据类型和复合数据类型）数组元素表示：数组名下标，数组名下标1下标2,数组名0数组名n-1Length域一元数组元素的复制=；System.arraycopy(fromfromIndex,to,toIndex,count),6.1数组示例1,/InitArray.java:initializinganarrayimportjava.io.*;publicclassInitArraypublicstaticvoidmain(Stringargs)intn=newint10;for(inti=0;in.length;i+)System.out.print(i+t+ni+n);,6.1数组示例2,/InitArray.javaimportjava.io.*;publicclassInitArraypublicstaticvoidmain(Stringargs)intn=32,27,64,18,95,14,90,70,60,37;for(inti=0;in.length;i+)System.out.print(i+t+ni+n“);,6.1数组示例3,/InitArray.javaimportjava.io.*;publicclassInitArraypublicstaticvoidmain(Stringargs)finalintARRAY_SIZE=10;intn=newintARRAY_SIZE;for(inti=0;in.length;i+)ni=2+2*i;for(inti=0;in.length;i+)System.out.print(i+t+ni+n“);,/BubbleSort.javaimportjava.applet.*;publicclassBubbleSortextendsAppletpublicvoidinit()inta=2,6,4,8,10,12,89,68,45,37;for(inti=0;i0;pass-)for(inti=0;ibi+1)swap(b,i,i+1);,6.1数组示例4,/JavaArrayUse.javapublicclassJavaArrayUsepublicstaticvoidmain(Stringargs)inti,j;intyoungMaxLevel=15;intyoung;young=newintyoungMaxLevel;for(i=0;iyoung.length;i+)youngi=newinti+1;young00=1;,6.1数组示例4(杨辉三角型）,for(i=1;iyoung.length;i+)youngi0=1;for(j=1;jyoungi.length-1;j+)youngij=youngi-1j-1+youngi-1j;youngiyoungi.length-1=1;for(i=0;iyoung.length;i+)for(j=0;jyoungi.length;j+)System.out.print(youngij+);System.out.println();,6.1数组示例4,6.1数组示例6（读程序）,importjava.applet.Applet;publicclassPassArrayextendsAppletpublicvoidinit()inta=1,2,3,4,5;for(inti=0;ia.length;i+)System.out.print(ai+);System.out.println();modifyArray(a);for(inti=0;ia.length;i+)System.out.print(ai+);System.out.println();,6.1数组示例6（读程序）,modifyElement(a3);System.out.print(a3);publicvoidmodifyArray(intb)for(intj=0;jb.length;j+)bj*=2;publicvoidmodifyElement(inte)e*=2;,6.1数组示例7,/Test.javapublicclassTestpublicstaticvoidmain(Stringargs)Pointpoint=newPoint(7,11);Circlecircle=newCircle(3.5,22,8);Cylindercylinder=newCylinder(10,3.3,10,10);ShapearrayOfShapes;arrayOfShapes=newShape3;arrayOfShapes0=point;,6.1数组示例7,arrayOfShapes1=circle;arrayOfShapes2=cylinder;for(inti=0;iarrayOfShapes.length;i+)System.out.println(nn+arrayOfShapesi.getName()+:+arrayOfShapesi.toString(),6.2字符串,创建字符串使用字符串,1.创建字符串,方法1：new方法Stringstr=newString();Stringstr=newString(Thisisastring);StringBufferstr=newStringBuffer(10);方法2：初始化方法Stringstr=Thisisastring;Stringstr;str=Thisisastring;字符串常量：helloworld,例1：构造方法,/StringConstructors.javapublicclassStringConstructorspublicstaticvoidmain(Stringargs)charcharArray=b,i,r,t;bytebyteArray=(byte)n,(byte)e,(byte)w,(byte)r;Strings,s1,s2,s3,s4,s5,s6;s=newString(hello);s1=newString();s2=newString(s);,例1：构造方法,s3=newString(charArray);s4=newString(charArray,1,2);s5=newString(byteArray,1,2);s6=newString(byteArray);System.out.print(s1=+s1+ns2=+s2+ns3=+s3+ns4=+s4+ns5=+s5+ns6=+s6+ns7=+s7);,例2：构造方法,publicclassStringBufferConstructorspublicstaticvoidmain(Stringargs)StringBufferbuf1,buf2,buf3;buf1=newStringBuffer();buf2=newStringBuffer(10);buf3=newStringBuffer(hello);System.out.println(buf1.toString();System.out.println(buf2.toString();System.out.println(buf3.toString();,2.使用字符串,String类访问：length(),charAt(),indexof(),lastIndexof(),getChars(),getBytes()等intlen=str.length();charc=str.charAt(i);inti=str.indexOf(a);inti=str.lastIndexOf(a);修改：concat(),replace(),substring(),toLowerCase(),toUpperCase()比较：equals(),equalsIgnoreCase(),CompareTo(),RegionMatches(),2.使用字符串,StringBuffer访问：length(),charAt(),getChars(),capacity();intcapa=str.capacity();修改：append(),insert(),setCharAt()str.append(“abc”);str.insert(4,“abc”);str.setChatAt(int,char);字符串的转化StringBuffer:toString():将可变字符串变成不变字符串String:valueOf():将不同类型的数字转化为不变字符串字符串的重载:+,例3：方法使用,/StringCompare.javapublicclassStringComparepublicstaticvoidmain(Stringargs)Strings1,s2,s3,s4,output;s1=newString(hello);s2=newString(goodbye);s3=newString(HappyBirthday);s4=newString(happybirthday);System.out.print(s1=+s1+ns2=+s2+ns3=+s3+ns4=+s4+nn);,例3：方法使用,if(s1.equals(hello)System.out.print(s1equalshellon);elseSystem.out.print(s1doesnotequalhellon);if(s1=hello)System.out.print(s1equalshellon);elseSystem.out.print(s1doesnotequalhellon);,例3：方法使用,if(s3.equalsIgnoreCase(s4)System.out.print(s3equalss4n);elseSystem.out.print(s3doesnotequals4n);System.out.print(pareTo(s2)is+pareTo(s2)+pareTo(s1)is+pareTo(s1)+pareTo(s1)is+pareTo(s1)+pareTo(s4)is+pareTo(s4)+pareTo(s3)is+pareTo(s3)+nn);,例3：方法使用,if(s3.regionMatches(0,s4,0,5)System.out.print(First5charactersofs3ands4matchn);elseSystem.out.print(First5charactersofs3ands4donotmatchn);if(s3.regionMatches(true,0,s4,0,5)System.out.print(First5charactersofs3ands4match);elseSystem.out.print(First5charactersofs3ands4donotmatch);,例4：方法使用,publicclassTestStringmyString=“2”;publicstaticvoidmain(Stringargs)TestmyObj=newTest()myObj.stringModifier(myObj.myString);System.out.println(“”+myObj.myString);voidstringModifier(StringtheString)theString=theString+“3”;System.out.print(theString);,内容要点,数组的创建及使用字符串的创建及使用,习题,随机产生十个数进行降序排序。修改例子中的冒泡排序，以提高性能。命令行参数的使用:从命令行输入需要排序的个数,将随机产生的数进行升序排序。编写一个应用程序，读入如07/21/1999格式的日期，打印出如July21，1999格式的日期。拼写检查器。,/StringTest.javapublicclassStringTestpublicstaticvoidmain(Stringargs)Strings=newString(07/21/1999);Strings1=s.substring(0,2);intm=Integer.parseInt(s1);switch(m)case1:System.out.print(January+s.substring(3,5)+,+s.substring(6,10);break;,case2:System.out.print(February+s.substring(3,5)+,+s.substring(6,10);break;case3:System.out.print(March+s.substring(3,5)+,+s.substring(6,10);break;case4:System.out.print(April+s.subst