java局部变量是从内部类访问的，需要声明为final
我试图从源代码编译this bot。然而，我遇到了一些错误
当我试图编译时，它给了我这些错误-
Information:Using javac 1.8.0_101 to compile java sources
Information:java: Errors occurred while compiling module 'BumpBot2'
Information:4/10/2016 10:27 PM - Compilation completed with 18 errors and 0 warnings in 1s 297ms
C:\Users\gabri\Desktop\BumpBot2\src\com\achow101\bumpbot\BumpBot.java
Error:(138, 30) java: local variable urlTextField is accessed from within inner class; needs to be declared final
Error:(139, 35) java: local variable bumpTextTextField is accessed from within inner class; needs to be declared final
Error:(144, 25) java: local variable errorText is accessed from within inner class; needs to be declared final
Error:(145, 25) java: local variable errorText is accessed from within inner class; needs to be declared final
Error:(149, 21) java: local variable errorText is accessed from within inner class; needs to be declared final
Error:(150, 21) java: local variable errorText is accessed from within inner class; needs to be declared final
Error:(172, 21) java: local variable errorText is accessed from within inner class; needs to be declared final
Error:(173, 21) java: local variable errorText is accessed from within inner class; needs to be declared final
Error:(253, 39) java: local variable grid is accessed from within inner class; needs to be declared final
Error:(256, 17) java: local variable urlTextField is accessed from within inner class; needs to be declared final
Error:(257, 17) java: local variable bumpTextTextField is accessed from within inner class; needs to be declared final
Error:(291, 64) java: local variable entry is accessed from within inner class; needs to be declared final
Error:(303, 17) java: local variable grid is accessed from within inner class; needs to be declared final
Error:(303, 43) java: local variable entryUrlLbl is accessed from within inner class; needs to be declared final
Error:(304, 17) java: local variable grid is accessed from within inner class; needs to be declared final
Error:(304, 43) java: local variable entryBumpTextLbl is accessed from within inner class; needs to be declared final
Error:(305, 17) java: local variable grid is accessed from within inner class; needs to be declared final
Error:(305, 43) java: local variable delBtn is accessed from within inner class; needs to be declared final
它们都与同一个文件BumpBot有关。JAVA 开发人员还提供了一个工作环境。jar文件，我已经使用过，100%有效。当我反编译它时，BumpBot。java输出是完全一样的
那么，我看不出有什么问题。我已经尝试在代码中将所有变量定义为final，它修复了我的大多数错误，但是它留下了关于entry和grid变量的四个解析错误
我的Java安装是否已损坏
[人力资源]
编辑： 这就是问题中的代码。太长了，请耐心听我说
public class BumpBot extends Application {
private int gridHeight = 0;
private static DoBumps doBumps = new DoBumps();
private static Thread t = new Thread(doBumps);
public static void main(String[] args)
{
// Start do bumps thread
t.start();
launch(args);
}
@Override
public void start(Stage primaryStage) throws Exception
{
// Set GUI Title
primaryStage.setTitle("Bitcointalk Thread Bump Bot");
// Create grid for entries
GridPane grid = new GridPane();
grid.setAlignment(Pos.TOP_CENTER);
grid.setHgap(10);
grid.setVgap(10);
grid.setPadding(new Insets(25, 25, 25, 25));
// URL Heading lable
Label urlLbl = new Label("Bitcointalk URL");
grid.add(urlLbl, 0, 0);
// New entry url textfield
TextField urlTextField = new TextField();
urlTextField.setPrefWidth(300);
grid.add(urlTextField, 0, 1);
gridHeight++;
// Bump Text heading label
Label bumpTextLbl = new Label("Bump Text");
grid.add(bumpTextLbl, 1, 0);
// New entry bump text textfield
TextField bumpTextTextField = new TextField();
bumpTextTextField.setPrefWidth(300);
grid.add(bumpTextTextField, 1, 1);
// Button to add entry
Button addBtn = new Button("Add Bump Entry");
grid.add(addBtn, 2, 1);
// Error text
Text errorText = new Text();
grid.add(errorText, 1, 2);
gridHeight += 2;
// Populate the grid with pre-existing entries
// Open a database connection
// (create a new database if it doesn't exist yet):
EntityManagerFactory emf = Persistence.createEntityManagerFactory("bumps.odb");
EntityManager em = emf.createEntityManager();
// Get the next thread to bump
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<BumpEntry> qNextBump = cb.createQuery(BumpEntry.class);
Root<BumpEntry> bump = qNextBump.from(BumpEntry.class);
qNextBump.select(bump);
TypedQuery<BumpEntry> query = em.createQuery(qNextBump);
List<BumpEntry> bumpList = query.getResultList();
for (BumpEntry entry : bumpList)
{
addEntryToGrid(entry, grid);
}
// Close the database connection:
em.close();
emf.close();
// Add the entry when clicked
addBtn.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent e) {
// Get the data from the form
String url = urlTextField.getText();
String bumpText = bumpTextTextField.getText();
// Check the URL
try {
if (!url.substring(0, 40).equals("https://bitcointalk.org/index.php?topic=")) {
errorText.setFill(Color.RED);
errorText.setText("Incorrect URL");
return;
}
} catch (StringIndexOutOfBoundsException e1) {
errorText.setFill(Color.RED);
errorText.setText("Incorrect URL");
return;
}
// Trim the URL to just the topic
String trimUrl = url.substring(0, 40);
int dotIndex = url.indexOf(".", 40);
trimUrl += url.substring(40, dotIndex);
trimUrl += ".0";
// Escape the bump text
//escapeInput(bumpText);
// Open a database connection
// (create a new database if it doesn't exist yet):
EntityManagerFactory emf = Persistence.createEntityManagerFactory("bumps.odb");
EntityManager em = emf.createEntityManager();
// Check that the thread is not already being bumped
BumpEntry bEntry = em.find(BumpEntry.class, trimUrl);
if (bEntry != null)
{
errorText.setFill(Color.RED);
errorText.setText("Thread already being bumped");
return;
}
// Create the entry
BumpEntry entry = new BumpEntry(trimUrl, bumpText, 0);
// Check the date of the last post
try {
// Get the first page of the thread
Document threadFirstPage = Jsoup.connect(url).get();
// Get the navpages elements
Element headerNavBar = threadFirstPage.select("div[id=bodyarea] > table[width=100%][cellspacing=0][cellpadding=0][border=0]").first();
Elements headerNavPages = headerNavBar.select("tr > td.middletext > a.navPages");
// Get the page if there is only one page of posts
if (headerNavPages.size() == 0) {
headerNavPages = headerNavBar.select("tr > td.middletext > b");
}
// Get the last page and calculate url number
Element lastPage = headerNavPages.last();
int pages = Integer.parseInt(lastPage.text());
int urlNum = (pages - 1) * 20;
// Create the URL for the last page
String lastPageUrl = url.substring(0, url.length() - 1);
lastPageUrl += urlNum;
// Get the last page of the thread
Document threadLastPage = Jsoup.connect(lastPageUrl).get();
// Get the last post in thread
Element postTable = threadLastPage.select("table[cellpadding=0][cellspacing=0][border=0][width=100%].bordercolor > tbody").first();
Element firstPost = postTable.select("tr").first();
String postClass = firstPost.className();
Elements posts = postTable.select("tr." + postClass);
Element lastPost = posts.last();
// Get the date of last post
Element headerAndPost = lastPost.select("td.td_headerandpost").first();
Element dateAndSubj = headerAndPost.select("table > tbody > tr > td[valign=middle]").get(1);
Element dateElem = dateAndSubj.select("div.smalltext").first();
String dateStr = dateElem.text();
// Parse date string and get unix timestamp
SimpleDateFormat fmt = new SimpleDateFormat("MMMM dd, yyyy, hh:mm:ss a");
fmt.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date;
if (dateStr.contains("Today")) {
date = new Date();
String currentDateStr = fmt.format(date);
dateStr = dateStr.replace("Today at", currentDateStr.substring(0, currentDateStr.lastIndexOf(",") + 1));
}
date = fmt.parse(dateStr);
long unixtime = date.getTime() / 1000;
entry.setTime(unixtime);
} catch (Exception e2) {
e2.printStackTrace();
}
// add entry to db
em.getTransaction().begin();
em.persist(entry);
em.getTransaction().commit();
// Notify the bumping thread
synchronized (doBumps)
{
doBumps.notify();
}
// Close the database connection:
em.close();
emf.close();
// Add the entry to display
addEntryToGrid(entry, grid);
// Clear textfields
urlTextField.clear();
bumpTextTextField.clear();
}
});
Scene scene = new Scene(grid, 1000, 800);
primaryStage.setScene(scene);
primaryStage.show();
}
public void addEntryToGrid(BumpEntry entry, GridPane grid)
{
// Thread URL
TextField entryUrlLbl = new TextField();
entryUrlLbl.setText(entry.getUrl());
entryUrlLbl.setEditable(false);
// Bump Text
TextField entryBumpTextLbl = new TextField();
entryBumpTextLbl.setText(entry.getBumpText());
entryBumpTextLbl.setEditable(false);
// Delete button
Button delBtn = new Button("Remove");
final int row = gridHeight;
delBtn.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
// Open a database connection
// (create a new database if it doesn't exist yet):
EntityManagerFactory emf = Persistence.createEntityManagerFactory("bumps.odb");
EntityManager em = emf.createEntityManager();
// Get the entry to be deleted
BumpEntry bumpEntry = em.find(BumpEntry.class, entry.getUrl());
// Remove entry from db
em.getTransaction().begin();
em.remove(bumpEntry);
em.getTransaction().commit();
// Close the database connection:
em.close();
emf.close();
// Clear this row's grid
grid.getChildren().remove(entryUrlLbl);
grid.getChildren().remove(entryBumpTextLbl);
grid.getChildren().remove(delBtn);
// Notify the bumping thread
synchronized (doBumps)
{
doBumps.notify();
}
}
});
// Add to display
grid.add(entryUrlLbl, 0, gridHeight);
grid.add(entryBumpTextLbl, 1, gridHeight);
grid.add(delBtn, 2, gridHeight);
gridHeight++;
}
@Override
public void stop()
{
System.exit(0);
}
public String escapeInput(String input) {
String[] characters = {"\"", "\\", "{", "}"};
StringBuilder sb = new StringBuilder();
sb.append("\"");
String line = input;
for (String test : characters) {
line = line.replace(test, "\\" + test);
}
sb.append("\"");
return sb.toString();
}
}
# 1 楼答案
正如苏雷什·阿塔在这里所说Difference between final and effectively final
如果不依赖于Java8，可以尝试用Java7编译它