我的程序中出现空指针异常，我不知道为什么。我有一个JavaFX UI，它为客户端上传文件提供了一些约束信息，我将它们作为线程类中的Constraints类的实例。当我选择实例并调用方法来查看值时，我可以看到它们，但是在run方法中，当我尝试通过套接字发送它们时，我打印它们并且什么也看不见。这是我的UI代码：
package Server;
/**
* Created by Ahmed on 15/03/2017 at 10:26 PM.
*/
/**
* Sample Skeleton for 'serverHome.fxml' Controller Class
*/
import constraintPackage.Constraints;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.CheckBox;
import javafx.scene.control.TextField;
import javafx.stage.DirectoryChooser;
import javafx.stage.Stage;
import java.io.File;
import java.io.Serializable;
import java.util.ArrayList;
public class serverHomeUI{
private WorkerThread workerThread = new WorkerThread();
private serverHome serverHome; //this is insignificant here
private boolean fileTypeButtonSelection = false;
private boolean numFileButtonSelection = false;
private boolean fileSizeButtonSelection = false;
private boolean delayButtonSelection = false;
private Constraints constraints = new Constraints();
void setServerHome(serverHome serverHome, String path){
this.serverHome = serverHome;
rootLocation.setText(path);
}
/*void setWorkerThread(WorkerThread workerThread){
this.workerThread = workerThread;
}*/
@FXML // fx:id="rootLocation"
private TextField rootLocation; // Value injected by FXMLLoader
@FXML // fx:id="browseButton"
private Button browseButton; // Value injected by FXMLLoader
@FXML // fx:id="cFile"
private CheckBox cFile; // Value injected by FXMLLoader
@FXML // fx:id="cppFile"
private CheckBox cppFile; // Value injected by FXMLLoader
@FXML // fx:id="javaFile"
private CheckBox javaFile; // Value injected by FXMLLoader
@FXML // fx:id="pyFile"
private CheckBox pyFile; // Value injected by FXMLLoader
@FXML // fx:id="phpFile"
private CheckBox phpFile; // Value injected by FXMLLoader
@FXML // fx:id="fileTypeButton"
private Button fileTypeButton; // Value injected by FXMLLoader
@FXML // fx:id="numFile"
private TextField numFile; // Value injected by FXMLLoader
@FXML // fx:id="numFileButton"
private Button numFileButton; // Value injected by FXMLLoader
@FXML // fx:id="maxFileSize"
private TextField maxFileSize; // Value injected by FXMLLoader
@FXML // fx:id="maxFileSizeButton"
private Button maxFileSizeButton; // Value injected by FXMLLoader
@FXML // fx:id="stdID"
private TextField stdID; // Value injected by FXMLLoader
@FXML // fx:id="stdIDButton"
private Button stdIDButton; // Value injected by FXMLLoader
@FXML // fx:id="delay"
private TextField delay; // Value injected by FXMLLoader
@FXML // fx:id="delayButton"
private Button delayButton; // Value injected by FXMLLoader
@FXML
void browseButtonFired(ActionEvent event) {
DirectoryChooser directoryChooser = new DirectoryChooser();
directoryChooser.setTitle("Choose Root Directory");
Stage stage = serverHome.stage;
File selectedDirectory = directoryChooser.showDialog(stage);
if(selectedDirectory != null){
rootLocation.setText(selectedDirectory.getAbsolutePath());
serverHome.setRoot(rootLocation.getText());
}
}
@FXML
void delayButtonFired(ActionEvent event) {
if(delay.getText() != null){
delayButtonSelection = true;
constraints.setDelayTime(Integer.parseInt(delay.getText()));
if(numFileButtonSelection && fileTypeButtonSelection && fileSizeButtonSelection && delayButtonSelection){
workerThread.sendConstraints(constraints);
}
}
}
@FXML
void fileTypeButtonFired(ActionEvent event) {
ArrayList<String> ticked = new ArrayList<>();
int i = 0;
if(cFile.isSelected() || cppFile.isSelected() || javaFile.isSelected() || pyFile.isSelected() || phpFile.isSelected()){
if(cFile.isSelected()){
ticked.add("c");
}
else if(!cFile.isSelected()){
ticked.remove("c");
}
else if(cppFile.isSelected()){
ticked.add("cpp");
}
else if(!cppFile.isSelected()){
ticked.remove("cpp");
}
else if(javaFile.isSelected()){
ticked.add("java");
}
else if(!javaFile.isSelected()){
ticked.remove("java");
}
else if(pyFile.isSelected()){
ticked.add("py");
}
else if(!pyFile.isSelected()){
ticked.remove("py");
}
else if(phpFile.isSelected()){
ticked.add("php");
}
else if(!phpFile.isSelected()){
ticked.remove("php");
}
fileTypeButtonSelection = true;
constraints.setFileTypes(ticked);
if(numFileButtonSelection && fileTypeButtonSelection && fileSizeButtonSelection && delayButtonSelection){
workerThread.sendConstraints(constraints);
}
}
}
@FXML
void maxFileSizeButtonFired(ActionEvent event) {
if(maxFileSize.getText() != null){
fileSizeButtonSelection = true;
constraints.setMaxFileSize(Float.parseFloat(maxFileSize.getText()));
if(numFileButtonSelection && fileTypeButtonSelection && fileSizeButtonSelection && delayButtonSelection){
workerThread.sendConstraints(constraints);
}
}
}
@FXML
void numFileButtonFired(ActionEvent event) {
if(numFile.getText() != null){
numFileButtonSelection = true;
constraints.setMaxNumFile(Integer.parseInt(numFile.getText()));
if(numFileButtonSelection && fileTypeButtonSelection && fileSizeButtonSelection && delayButtonSelection){
workerThread.sendConstraints(constraints);
}
}
}
@FXML
void stdIDButtonFired(ActionEvent event) {
}
}
这是我的线程代码
class WorkerThread implements Runnable
{
private Hashtable<String, Integer> hashTable = new Hashtable<>();
private Socket socket;
private InputStream inputStream = null;
private OutputStream outputStream = null;
private InputStreamReader inputStreamReader = null;
private BufferedReader bufferedReader = null;
private PrintWriter printWriter = null;
private ObjectOutputStream objectOutputStream = null;
private ObjectInputStream objectInputStream = null;
private constraintCreated = false;
private Constraints constraints1;
private int id = 0;
void sendConstraints(Constraints constraints){
System.out.println("hello bai, constraint false");
constraints1 = constraints;
constraintCreated = true;
System.out.println("constraint true");
System.out.println(this.constraints1.getDelayTime());//these two lines give
System.out.println(this.constraints1.getFileNum());//proper output
}
public WorkerThread(){
}
public WorkerThread(Socket s)
{
this.socket = s;
try {
inputStream = socket.getInputStream();
outputStream = socket.getOutputStream();
objectInputStream = new ObjectInputStream(inputStream);
objectOutputStream = new ObjectOutputStream(outputStream);
inputStreamReader= new InputStreamReader(inputStream);
bufferedReader = new BufferedReader(inputStreamReader);
printWriter = new PrintWriter(outputStream);
} catch (IOException e) {
e.printStackTrace();
}
String clientIP = s.getInetAddress().toString();
String studentID = null;
int stdID = 0;
try {
studentID = bufferedReader.readLine();
stdID = Integer.parseInt(studentID);
} catch (IOException e) {
e.printStackTrace();
}
hashTable.put(clientIP, stdID);
System.out.println(root1); //root1="G:\Akib Ahmed\Pdf\3-2\(CSE 321, 322) Computer Networks\Lab\Offline 1 (Code Repository)\src\Server\Root"
File file = new File(root1);
if(!file.exists()){
boolean a = file.mkdir();
file = new File(root1 + "\\"+stdID);
if(!file.exists()) {
boolean b = file.mkdir();
}
}
this.id = id;
}
public void run() {
Constraints constraints = new Constraints();
if (printWriter != null) {
printWriter.print("Your id is: " + this.id);
printWriter.println();
printWriter.flush();
}
String str = null;
while (true) {
try {
System.out.println("inside while loops");
str = bufferedReader.readLine();
System.out.println(str);
if (str != null) {
if(str.equals("Constraints")){ //reading str by bufferedReader
System.out.println("going to send constraints");
//while(!constraintCreated) {if(constraints1 == null) System.out.println("something");} //this went on an inifinite loop
if(constraintCreated) System.out.println("really!"); //constraintCreated is false here, although I have assigned it true earlier
System.out.println(constraints1.getDelayTime()); //null pointer exception and compilation never goes further
ArrayList<String> filetyp = constraints1.getFileTypes();
objectOutputStream.writeObject(filetyp);
objectOutputStream.flush();
printWriter.write(String.valueOf(constraints1.getFileSize()));
printWriter.println();
printWriter.flush();
printWriter.write(String.valueOf(constraints1.getFileNum()));
printWriter.println();
printWriter.flush();
printWriter.write(String.valueOf(constraints1.getDelayTime()));
printWriter.println();
printWriter.flush();
System.out.println(constraints1.getDelayTime());
System.out.println("sent Constraints");
}
}
else{
System.out.println("here????");
}
} catch (Exception e) {
e.printStackTrace();
System.err.println("Problem in communicating with the client [" + id + "]. Terminating worker thread.");
break;
}
}
ShowOff.workerThreadCount--;
System.out.println("Client [" + id + "] is now terminating. No. of worker threads = "
+ ShowOff.workerThreadCount);
}
}