《Java语言程序设计基础篇》第10版 梁勇 著第二十八章练习题答案.docx

《Java语言程序设计基础篇》第10版 梁勇 著第二十八章练习题答案.docx

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《Java语言程序设计基础篇》第10版梁勇著第二十八章练习题答案

《Java语言程序设计（基础篇）》（第10版梁勇著）

第二十八章练习题答案

28.1

publicclassExercise28_01{

publicstaticvoidmain（String[]args）throwsException{

java.util.Scannerinput=newjava.util.Scanner（System.in）;

System.out.print（"Enterafilename:

"）;

java.io.Filefile=newjava.io.File（input.nextLine（））;

if（!

file.exists（））{

System.out.println（"Filedoesnotexist"）;

System.exit

（1）;

}

java.util.ScannerinFile=newjava.util.Scanner（file）;

//Readthenumberofvertices

Strings=inFile.nextLine（）;

intnumberOfVertices=Integer.parseInt（s）;

System.out.println（"Thenumberofverticesis"

+numberOfVertices）;

java.util.Listlist=newjava.util.ArrayList<>（）;

while（inFile.hasNext（））{

s=inFile.nextLine（）;

String[]tokens=s.split（"[\\s+]"）;

intstartingVertex=Integer.parseInt（tokens[0].trim（））;

for（inti=1;i

intadjacentVertex=Integer.parseInt（tokens[i].trim（））;

list.add（newAbstractGraph.Edge（startingVertex,adjacentVertex））;

}

}

Graphgraph=newUnweightedGraph<>（list,numberOfVertices）;

graph.printEdges（）;

AbstractGraph.Treetree=graph.dfs（0）;

if（tree.getNumberOfVerticesFound（）==numberOfVertices）

System.out.println（"Thegraphisconnected"）;

else

System.out.println（"Thegraphisnotconnected"）;

}

}

28.2

publicclassExercise28_02{

publicstaticvoidmain（String[]args）throwsjava.io.FileNotFoundException{

String[]vertices={"Seattle","SanFrancisco","LosAngeles",

"Denver","KansasCity","Chicago","Boston","NewYork",

"Atlanta","Miami","Dallas","Houston"};

int[][]edges={

{0,1},{0,3},{0,5},

{1,0},{1,2},{1,3},

{2,1},{2,3},{2,4},{2,10},

{3,0},{3,1},{3,2},{3,4},{3,5},

{4,2},{4,3},{4,5},{4,7},{4,8},{4,10},

{5,0},{5,3},{5,4},{5,6},{5,7},

{6,5},{6,7},

{7,4},{7,5},{7,6},{7,8},

{8,4},{8,7},{8,9},{8,10},{8,11},

{9,8},{9,11},

{10,2},{10,4},{10,8},{10,11},

{11,8},{11,9},{11,10}

};

java.io.PrintWriteroutput=newjava.io.PrintWriter（"Exercise28_02.txt"）;

intnumberOfVertices=vertices.length;

output.println（numberOfVertices）;

for（intstartingVertex=0;startingVertex

output.print（startingVertex+""）;

intcount=0;

for（inti=0;i

if（edges[i][0]==startingVertex）{

count++;

if（count==1）

output.print（edges[i][1]）;

else

output.print（""+edges[i][1]）;

}

}

if（count>0）output.println（）;

}

System.out.println（"Done!

"）;

output.close（）;

}

}

28.4

importjava.util.*;

publicclassExercise28_04{

publicstaticvoidmain（String[]args）{

String[]vertices={"Seattle","SanFrancisco","LosAngeles","Denver",

"KansasCity","Chicago","Boston","NewYork","Atlanta","Miami",

"Dallas","Houston","Savannah","Charlston"};

int[][]edges={{0,1},{0,3},{0,5},{1,0},{1,2},

{1,3},{2,1},{2,3},{2,4},{2,10},{3,0},{3,1},

{3,2},{3,4},{3,5},{4,2},{4,3},{4,5},{4,7},

{4,8},{4,10},{5,0},{5,3},{5,4},{5,6},{5,7},

{6,5},{6,7},{7,4},{7,5},{7,6},{7,8},{8,4},

{8,7},{8,9},{8,10},{8,11},{9,8},{9,11},

{10,2},{10,4},{10,8},{10,11},{11,8},{11,9},

{11,10},{12,13},{13,12}};

MyGraphgraph=newMyGraph（edges,vertices）;

AbstractGraph.Treedfs=graph.dfs（graph.getIndex（"Chicago"））;

System.out.println（graph.getConnectedComponents（））;

}

publicstaticclassMyGraphextendsUnweightedGraph{

/**Constructanemptygraph*/

publicMyGraph（）{

}

/**Constructagraphfromedgesandverticesstoredinarrays*/

publicMyGraph（int[][]edges,V[]vertices）{

super（vertices,edges）;

}

/**ConstructagraphfromedgesandverticesstoredinList*/

publicMyGraph（Listvertices,Listedges）{

super（vertices,edges）;

}

/**Constructagraphforintegervertices0,1,2andedgelist*/

publicMyGraph（Listedges,intnumberOfVertices）{

super（edges,numberOfVertices）;

}

/**Constructagraphfromintegervertices0,1,andedgearray*/

publicMyGraph（int[][]edges,intnumberOfVertices）{

super（edges,numberOfVertices）;

}

publicList>getConnectedComponents（）{

List>list=newArrayList>（）;

ListvertexIndices=newArrayList（）;

for（inti=0;i

vertexIndices.add（i）;

while（vertexIndices.size（）>0）{

Treetree=dfs（vertexIndices.get（0））;

list.add（tree.getSearchOrder（））;

vertexIndices.removeAll（tree.getSearchOrder（））;

}

returnlist;

}

}

}

28.10

publicclassExercise28_10{

publicstaticvoidmain（String[]args）throwsException{

java.util.Scannerinput=newjava.util.Scanner（System.in）;

System.out.print（"Enterafilename:

"）;

java.io.Filefile=newjava.io.File（input.nextLine（））;

if（!

file.exists（））{

System.out.println（"Filedoesnotexist"）;

System.exit

（1）;

}

System.out.print（"Entertwovertices（integerindexes）:

"）;

intv1=input.nextInt（）;

intv2=input.nextInt（）;

java.util.ScannerinFile=newjava.util.Scanner（file）;

//Readthenumberofvertices

Strings=inFile.nextLine（）;

intnumberOfVertices=Integer.parseInt（s）;

System.out.println（"Thenumberofverticesis"+numberOfVertices）;

java.util.Listlist=

newjava.util.ArrayList（）;

while（inFile.hasNext（））{

s=inFile.nextLine（）;

String[]tokens=s.split（"[\\s+]"）;

intv=Integer.parseInt（tokens[0].trim（））;

for（inti=1;i

intadjacentVertex=Integer.parseInt（tokens[i].trim（））;

list.add（newAbstractGraph.Edge（v,adjacentVertex））;

}

}

Graphgraph=newUnweightedGraph<>（list,numberOfVertices）;

graph.printEdges（）;

AbstractGraph.Treetree=graph.bfs（v1）;

java.util.Listpath=tree.getPath（v2）;

System.out.print（"Thepathis"）;

for（inti=0;i

System.out.print（path.get（i）+""）;

}

}

28.11

importjavafx.application.Application;

importjavafx.stage.Stage;

importjavafx.scene.Scene;

importjavafx.scene.control.Button;

importjavafx.scene.control.Label;

importjavafx.scene.layout.BorderPane;

importjavafx.scene.layout.HBox;

importjavafx.scene.layout.GridPane;

importjavafx.scene.paint.Color;

importjavafx.geometry.Pos;

importjavafx.scene.control.ScrollPane;

importjavafx.scene.text.Font;

publicclassExercise28_11extendsApplication{

//Createtheinitialboard

privateInitialNodePaneinitialNodePane=newInitialNodePane（）;

privateButtonbtSolve=newButton（"Solve"）;

privateButtonbtStartOver=newButton（"StartOver"）;

privateNineTailModelmodel=newNineTailModel（）;

@Override//OverridethestartmethodintheApplicationclass

publicvoidstart（StageprimaryStage）{

BorderPanepane=newBorderPane（）;

//solutionPanelholdsasequenceofpanelsfordisplayingnodes

HBoxhBox=newHBox（5）;

hBox.getChildren（）.addAll（btSolve,btStartOver）;

hBox.setAlignment（Pos.CENTER）;

HBoxsolutionPane=newHBox（5）;

solutionPane.getChildren（）.add（initialNodePane）;

pane.setCenter（newScrollPane（solutionPane））;

pane.setBottom（hBox）;

//Createasceneandplacethepaneinthestage

Scenescene=newScene（pane,650,250）;

primaryStage.setTitle（"Exercise28_11:

NineTailProblem"）;//Setthestagetitle

primaryStage.setScene（scene）;//Placethesceneinthestage

primaryStage.show（）;//Displaythestage

//ListenerfortheSolvebutton

btSolve.setOnAction（e->{

solutionPane.getChildren（）.clear（）;

//Getashortestpath

java.util.Listlist=model

.getShortestPath（NineTailModel

.getIndex（initialNodePane.getNode（）））;

//Displaynodesintheshortestpath

for（inti=0;i

if（i!

=0）{

solutionPane.getChildren（）.add（newNodePane（NineTailModel

.getNode（list.get（i））,NineTailModel

.getNode（list.get（i-1））））;

}else{

solutionPane.getChildren（）.add（newNodePane（NineTailModel

.getNode（list.get（i））））;

}

}

}）;

//ListenerfortheStartOverbutton

btStartOver.setOnAction（e->{

solutionPane.getChildren（）.clear（）;

solutionPane.getChildren（）.add（initialNodePane）;//Displayinitialnode

}）;

}

/**

*ThemainmethodisonlyneededfortheIDEwithlimited

*JavaFXsupport.Notneededforrunningfromthecommandline.

*/

publicstaticvoidmain（String[]args）{

launch（args）;

}

/**

*Aninnerclassfordisplayinganodeonagridpane

*/

staticclassNodePaneextendsGridPane{

publicNodePane（char[]node）{

this.setStyle（"-fx-border-color:

black"）;

for（inti=0;i<9;i++）{

add（newCell（node[i]+""）,i%3,i/3）;

}

}

publicNodePane（char[]newNode,char[]oldNode）{

this.setStyle（"-fx-border-color:

black"）;

for（inti=0;i<9;i++）{

if（newNode[i]==oldNode[i]）{

add（newCell（newNode[i]+"",Color.BLACK）,i%3,i/3）;

}else{

add（newCell（newNode[i]+"",Color.RED）,i%3,i/3）;

}

}

}

}

/**

*Aninnerclassfordisplayingacell

*/

staticclassCellextendsLabel{

publicCell（Strings）{

this.setFont（newFont（"Times",40））;

setText（s）;

}

publicCell（Strings,Colorcolor）{

this.setFont（newFont（"Times",40））;

this.setTextFill（color）;

setText（s）;

}

}

/**

*Aninnerclassfordisplayingtheinitialnode

*/

staticclassInitialNodePaneextendsGridPane{

//Eachcellrepresentsacoin,whichcanbeflipped

ClickableCell[][]clickableCells=newClickableCell[3][3];

publi