《Java語言程序設計（基礎篇）》（第10版梁勇著）

第十九章練習題答案19.1classGenericStack<E>{publicfinalstaticintINITIAL_SIZE=16;privateE[]elements;privateintsize;/**Constructastackwiththedefaultinitialcapacity*/publicGenericStack(){this(INITIAL_SIZE);)/**Constructastackwiththespecifiedinitialcapacity*/publicGenericStack(intinitialCapacity){elements=(E[])newObject[initialCapacity];)/**Pushanewelementintothetopofthestack*/publicEpush(Evalue){if(size>=elements.length){E[]temp=(E[])newObject[elements.length*2];System.arraycopy(elements,0,temp,0,elements.length);elements=temp;)returnelements[size++]=value;)/**Returnandremovethetopelementfromthestack*/publicEpop(){returnelements[--size];)/**Returnthetopelementfromthestack*/publicEpeek(){returnelements[size-1];)/**Exercise03_21whetherthestackisempty*/publicbooleanisEmpty(){returnsize==0;)/**Returnthenumberofelementsinthestack*/publicintgetSize(){returnsize;))19.2publicclassExercise19_02{publicstaticvoidmain(String[]args){GenericStack<String>stack=newGenericStack<String>();stack.push("Tom");stack.push("George");stack.push("Peter");System.out.println(stack.getSize());System.out.println(stack.peek());System.out.println(stack.pop());System.out.println(stack.peek());)//GenericStack.java:ImplementingastackusinginheritancestaticclassGenericStack<E>extendsjava.util.ArrayList<E>{publicbooleanisEmpty(){returnsuper.isEmpty();)publicintgetSize(){returnsize();)publicObjectpeek(){returnget(getSize()-1);)publicObjectpop(){Objecto=get(getSize()-1);remove(getSize()-1);returno;)publicObjectpush(Eo){

add(o);returno;)publicintsearch(Objecto){returnindexOf(o);)?OverridepublicStringtoString(){return"stack:"+toString();)))19.3importjava.util.ArrayList;publicclassExercise19_03{publicstaticvoidmain(String[]args){ArrayList<Integer>list=newArrayList<Integer>();list.add(14);list.add(24);list.add(14);list.add(42);list.add(25);ArrayList<Integer>newList=removeDuplicates(list);System.out.print(newList);)publicstatic<E>ArrayList<E>removeDuplicates(ArrayList<E>list){ArrayList<E>result=newArrayList<E>();for(Ee:list){if(!result.contains(e))result.add(e);returnresult;returnresult;)19.4publicclassExercise19_04{publicstatic<EextendsComparable<E>>voidselectionSort(E[]list){for(inti=1;i<list.length;i++){/**insertlist[i]intoasortedsublistlist[0..i-1]sothatlist[0..i]issorted.*/EcurrentElement=list[i];intk;for(k=i-1;k>=0&&list[k].compareTo(currentElement)>0;k--){list[k+1]=list[k];)//Insertthecurrentelementintolist[k+1]list[k+1]=currentElement;)))19.5publicclassExercise19_05{publicstaticvoidmain(String[]args){Integer[]numbers={1,2,3};System.out.println(max(numbers));String[]words={"red","green","blue"};System.out.println(max(words));Circle[]circles={newCircle(3),newCircle(2.9),newCircle(5.9)};System.out.println(max(circles));}staticclassCircleimplementsComparable<Circle>{doubleradius;publicCircle(doubleradius){this.radius=radius;}?OverridepublicintcompareTo(Circlec){if(radius<c.radius)return-1;elseif(radius==c.radius)return0;elsereturn1;)?OverridepublicStringtoString(){return"Circleradius:"+radius;))publicstatic<EextendsComparable<E>>Emax(E[]list){Emax=list[0];for(inti=1;i<list.length;i++){if(pareTo(list[i])<0){max=list[i];))returnmax;))19.6publicclassExercise19_06{publicstaticvoidmain(String[]args){Integer[][]numbers={{1,2,3},{4,4,6});System.out.println(max(numbers));}publicstatic<EextendsComparable<E>>Emax(E[][]list){Emax=list[0][0];for(inti=1;i<list.length;i++){for(intj=1;j<list[i].length;j++){if(pareTo(list[i][j])<0){max=list[i][j];}returnmax;))19.7publicclassExercise19_07{/**Usebinarysearchtofindthekeyinthelist*/publicstatic<EextendsComparable<E>>intbinarySearch(E[]list,Ekey){intlow=0;inthigh=list.length-1;while(high>=low){intmid=(low+high)/2;if(pareTo(list[mid])<0){high=mid-1;)elseif(key.equals(list[mid])){returnmid;)else{low=mid+1;))return-low-1;//Nowhigh<low))19.8importjava.util.ArrayList;publicclassExercise19_08{publicstaticvoidmain(String[]args){ArrayList<Integer>list=newArrayList<Integer>();list.add(14);list.add(24);list.add(4);list.add(42);list.add(5);shuffle(list);for(inti=0;i<list.size();i++)System.out.print(list.get(i)+"");)publicstatic<E>voidshuffle(ArrayList<E>list){for(inti=0;i<list.size()-1;i++){intindex=(int)(Math.random()*list.size());Etemp=list.get(i);list.set(i,list.get(index));list.set(index,temp);)))19.9importjava.util.ArrayList;publicclassExercise19_09{publicstaticvoidmain(String[]args){ArrayList<Integer>list=newArrayList<Integer>();list.add(14);list.add(24);list.add(4);list.add(42);list.add(5);Exercise19_09.<Integer>sort(list);System.out.print(list);)/**Sortanarrayofcomparableobjects*/publicstatic<EextendsComparable<E>>voidsort(ArrayList<E>list){EcurrentMin;intcurrentMinIndex;for(inti=0;i<list.size()-1;i++){//Findtheminimuminthelist[i+1..list.length-2]currentMin=list.get(i);currentMinIndex=i;for(intj=i+1;j<list.size();j++){if(currentMpareTo(list.get(j))>0){currentMin=list.get(j);currentMinIndex=j;))//Swaplist[i]withlist[currentMinIndex]ifnecessary;if(currentMinIndex!=i){list.set(currentMinIndex,list.get(i));list.set(i,currentMin);))))19.10importjava.util.ArrayList;publicclassExercise19_10{publicstaticvoidmain(String[]args){ArrayList<Integer>list=newArrayList<Integer>();list.add(14);list.add(24);list.add(4);list.add(42);list.add(5);System.out.print(max(list));)publicstatic<EextendsComparable<E>>Emax(ArrayList<E>list){EcurrentMax=list.get(0);for(inti=1;i<list.size();i++)if(currentMpareTo(list.get(i))<0)currentMax=list.get(i);returncurrentMax;))19.11importjava.util.ArrayList;publicclassExercise19_11{publicstaticvoidmain(String[]args){//CreatetwoComplexarraysm1andm2Complex[][]m1=newComplex[3][3];Complex[][]m2=newComplex[3][3];TOC\o"1-5"\h\zfor(inti= 0;i<m1.length; i++)for(intj = 0;j<m1[0].length; j++){m1[i][j] = newComplex(i+ 1,j + 5);m2[i][j] = newComplex(i+ 1,j + 6);)//CreateaninstanceofComplexMatrixComplexMatrixrationalMatrix=newComplexMatrix();System.out.println("\nm1+m2is");GenericMatrix.printResult(m1,m2,rationalMatrix.addMatrix(m1,m2),'+');System.out.println("\nm1*m2is");GenericMatrix.printResult(m1,m2,rationalMatrix.multiplyMatrix(m1,m2),'*');)publicstatic<E>ArrayList<E>removeDuplicates(ArrayList<E>list){ArrayList<E>result=newArrayList<E>();for(Ee:list){if(!result.contains(e))result.add(e);)returnresult;))classComplexMatrixextendsGenericMatrix<Complex>{?Override/**Addtworationalnumbers*/protectedComplexadd(Complexr1,Complexr2){returnr1.add(r2);)?Override/**Multiplytworationalnumbers*/protectedComplexmultiply(Complexr1,Complexr2){returnr1.multiply(r2);)?Override/**SpecifyzeroforaComplexnumber*/protectedComplexzero(){returnnewComplex(0,0);))abstractclassGenericMatrix<E>{/**Abstractmethodforaddingtwoelementsofthematrices*/protectedabstractEadd(Eo1,Eo2);/**Abstractmethodformultiplyingtwoelementsofthematrices*/protectedabstractEmultiply(Eo1,Eo2);/**Abstractmethodfordefiningzeroforthematrixelement*/protectedabstractEzero();/**Addtwomatrices*/publicE[][]addMatrix(E[][]matrix1,E[][]matrix2){//Checkboundsofthetwomatricesif((matrix1.length!=matrix2.length)||(matrix1[0].length!=matrix2[0].length)){thrownewRuntimeException("Thematricesdonothavethesamesize");)E[][]result=(E[][])newObject[matrix1.length][matrix1[0].length];//Performadditionfor(inti=0;i<result.length;i++)for(intj=0;j<result[i].length;j++){result[i][j]=add(matrix1[i][j],matrix2[i][j]);)returnresult;)/**Multiplytwomatrices*/publicE[][]multiplyMatrix(E[][]matrix1,E[][]matrix2){//Checkboundsif(matrix1[0].length!=matrix2.length){thrownewRuntimeException("Thematricesdonothavecompatiblesize");)//Createresul