您的代码存在问题
@FXML 是控制器实例的注入注解，不应与 static 成员或使用 new 关键字初始化的成员一起使用。
您的控制器中的定义应该是：
@FXML private PasswordField passwordBox;
可能适用也可能不适用于您的情况的其他注意事项
- 应始终通过新的 FXMLLoader().load(...) 调用创建控制器实例（而不是通过控制器本身的
new 关键字，除非您随后使用 loader.setController()）。
- fxml 文件必须为您的密码字段指定一个 名称，该名称与您的控制器中的名称相匹配（在您的情况下，此名称为
passwordBox）。
示例
GatewayApplication.java
package application;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;
import java.io.IOException;
public class GatewayApplication extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage stage) throws IOException {
FXMLLoader loader = new FXMLLoader(getClass().getResource("passport.fxml"));
AnchorPane layout = loader.load();
stage.setScene(new Scene(layout));
stage.show();
}
}
MainController.java
由SceneBuilderView | Show Sample Skeleton生成。
package application;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.AnchorPane;
public class MainController {
@FXML
private ResourceBundle resources;
@FXML
private URL location;
@FXML
private Button connectButton;
@FXML
private ImageView favoritesButton;
@FXML
private AnchorPane mainAnchor;
@FXML
private PasswordField passwordBox;
@FXML
private Label passwordLbl;
@FXML
private TextField portBox;
@FXML
private Label portLbl;
@FXML
private TextField serverIPBox;
@FXML
private Label serverIPLbl;
@FXML
private ImageView settingsButton;
@FXML
private TextField usernameBox;
@FXML
private Label usernameLbl;
@FXML
void connectClicked(ActionEvent event) {
System.out.println("password = " + passwordBox.getText());
}
@FXML
void favoritesClicked(MouseEvent event) {
}
@FXML
void settingsClicked(MouseEvent event) {
}
@FXML
void initialize() {
assert connectButton != null : "fx:id=\"connectButton\" was not injected: check your FXML file 'passport.fxml'.";
assert favoritesButton != null : "fx:id=\"favoritesButton\" was not injected: check your FXML file 'passport.fxml'.";
assert mainAnchor != null : "fx:id=\"mainAnchor\" was not injected: check your FXML file 'passport.fxml'.";
assert passwordBox != null : "fx:id=\"passwordBox\" was not injected: check your FXML file 'passport.fxml'.";
assert passwordLbl != null : "fx:id=\"passwordLbl\" was not injected: check your FXML file 'passport.fxml'.";
assert portBox != null : "fx:id=\"portBox\" was not injected: check your FXML file 'passport.fxml'.";
assert portLbl != null : "fx:id=\"portLbl\" was not injected: check your FXML file 'passport.fxml'.";
assert serverIPBox != null : "fx:id=\"serverIPBox\" was not injected: check your FXML file 'passport.fxml'.";
assert serverIPLbl != null : "fx:id=\"serverIPLbl\" was not injected: check your FXML file 'passport.fxml'.";
assert settingsButton != null : "fx:id=\"settingsButton\" was not injected: check your FXML file 'passport.fxml'.";
assert usernameBox != null : "fx:id=\"usernameBox\" was not injected: check your FXML file 'passport.fxml'.";
assert usernameLbl != null : "fx:id=\"usernameLbl\" was not injected: check your FXML file 'passport.fxml'.";
}
}
style.css
.root {
-fx-background-color: cornsilk;
}
passport.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<?import java.net.URL?>
<AnchorPane fx:id="mainAnchor" opacity="1.0" prefHeight="200.0" prefWidth="408.0000999999975" styleClass="back" xmlns:fx="http://javafx.com/fxml" fx:controller="application.MainController">
<children>
<Label fx:id="serverIPLbl" layoutX="14.0" layoutY="28.0" prefWidth="175.0" text="Server IP">
<font>
<Font name="Segoe UI" size="12.0" fx:id="x1" />
</font>
</Label>
<TextField fx:id="serverIPBox" layoutX="14.0" layoutY="50.0" prefWidth="175.0" />
<Label fx:id="portLbl" font="$x1" layoutX="215.0" layoutY="28.0" prefWidth="175.0" text="Port" />
<TextField fx:id="portBox" layoutX="215.0" layoutY="50.0" prefWidth="175.0" />
<Label fx:id="passwordLbl" font="$x1" layoutX="14.0" layoutY="81.0" prefWidth="175.0" text="Server Password" />
<ImageView fx:id="settingsButton" fitHeight="23.0" fitWidth="23.0" layoutX="14.0" layoutY="137.0" onMouseClicked="#settingsClicked" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="http://icons.iconarchive.com/icons/hopstarter/soft-scraps/24/Gear-icon.png" />
</image>
</ImageView>
<Button id="startServer" fx:id="connectButton" layoutX="14.0" layoutY="167.0" mnemonicParsing="false" onAction="#connectClicked" prefHeight="22.0" prefWidth="376.0" text="Connect" />
<Label fx:id="usernameLbl" font="$x1" layoutX="215.0" layoutY="81.0" prefWidth="175.0" text="Username" />
<TextField id="serverIPBox" fx:id="usernameBox" layoutX="215.0" layoutY="103.0" prefWidth="175.0" promptText="a-z A-Z 0-9 _ - chars allowed" />
<ImageView id="favoriteButton" fx:id="favoritesButton" fitHeight="23.0" fitWidth="23.0" layoutX="55.0" layoutY="137.0" onMouseClicked="#favoritesClicked" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="http://icons.iconarchive.com/icons/hopstarter/soft-scraps/24/Button-Favorite-icon.png"/>
</image>
</ImageView>
<PasswordField fx:id="passwordBox" layoutX="14.0" layoutY="103.0" prefWidth="175.0" promptText="Optional" />
</children>
<stylesheets>
<URL value="@style.css" />
</stylesheets>
</AnchorPane>
示例程序 UI
示例程序输出
在密码字段中输入魔法作品“xyzzy”并按下连接，程序会从该字段中提取密码并将其打印到控制台：
password = xyzzy
使用的测试系统是运行 Java 8b121 的 OS X 10.9。
在以后的此类问题中，您可能需要提供minimal, complete, tested and readable example。并非所有问题都需要这样的样本，但肯定会对这个问题有所帮助。