《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;iintadjacentVertex=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;startingVertexoutput.print（startingVertex+""）;
intcount=0;
for（inti=0;iif（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;ivertexIndices.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;iintadjacentVertex=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;iSystem.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;iif（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
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