javafx 按钮从 txt 读取行到文本字段

Question

我正在创建一个用于打开和关闭函数的文件对象。 现在我指向一个特定的位置并使用一个固定的名称。该文件填充有数据行。 按钮在窗格上，我有一个 openContact 函数，它应该逐行读取文本文件并将结果发送到文本字段 setText 方法，当您单击按钮时会调用此函数。 编辑器中没有语法错误，但单击按钮不会填充 GUI 中的字段。 除此之外，我不确定要问什么问题或要搜索什么。 我按原样附上我的代码。 对于要提出的适当问题或思考过程的任何提示或指导，我们将不胜感激。

package programmingassignment1;

import java.awt.Image;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.RadioButton;
import javafx.scene.control.TextArea;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.*;
//import javafx.scene.layout.StackPane;
//import javafx.scene.layout.HBox;
import javafx.stage.Stage;

import java.io.*; //input/output
import java.util.Scanner;
//import java.util.*; //scanner, user input
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.image.ImageView;
import javafx.scene.shape.Rectangle;
import javafx.stage.FileChooser;
import javafx.stage.FileChooser.ExtensionFilter;

public class Address extends Application {
    String contactFirst,
           contactLast,
           spouseFirst,
           spouseLast,
           street,
           city,
           state,
           zip;
    TextField tf_contactFirst = new TextField();
    TextField tf_contactLast = new TextField();
    TextField tf_spouseFirst = new TextField();
    TextField tf_spouseLast = new TextField(); 
    TextField tf_street = new TextField();
    TextField tf_city = new TextField();
    TextField tf_state = new TextField();
    TextField tf_zip = new TextField();
    TextArea ta_notes = new TextArea();

    ExtensionFilter jpgExtension = new ExtensionFilter("JPG", "*.jpg");
    ExtensionFilter pngExtension = new ExtensionFilter("PNG", "*.png");
    ExtensionFilter allExtension = new ExtensionFilter("ALL", "*.*");
    Rectangle imageBox = new Rectangle(10, 0, 10, 20);
    FileChooser fc = new FileChooser();
    @Override
    public void start(Stage primaryStage){
        //modify text area and register actions
        ta_notes.setWrapText(true);
        ta_notes.setEditable(true);
        ta_notes.setPrefColumnCount(12);
        ta_notes.setPrefRowCount(3);

//Setting an action for the Clear button       
        Button bt_cancel = new Button("Cancel");
        bt_cancel.setOnAction(e -> {
            tf_contactFirst.clear();
            tf_contactLast.clear();
            tf_spouseFirst.clear();
            tf_spouseLast.clear();
            tf_street.clear();
            tf_city.clear();
            tf_state.clear();
            tf_zip.clear();

            ta_notes.setText(null);
    });

//Setting an action for the Open Contact  button       
        Button bt_openContact = new Button("Open Contact");
        File file = new File("AddressBook.txt");
        bt_openContact.setOnAction(e -> {
            new EventHandler<ActionEvent>(){
                @Override
                public void handle(ActionEvent e){
                    try{openContact(file);}
                    catch(Exception f){f.getMessage();}
                }
            };
        });
//Setting an action for the Save button        
        Button bt_save = new Button("Save");

        bt_save.setOnAction(
            new EventHandler<ActionEvent>(){
                @Override
                public void handle(ActionEvent e){
                    try{saveContact(file);}
                    catch(Exception f){f.getMessage();}
        }});

        RadioButton rb_male = new RadioButton("Male");
        RadioButton rb_female = new RadioButton("Female");

        ToggleGroup tgrp = new ToggleGroup();
        rb_male.setToggleGroup(tgrp);
        rb_female.setToggleGroup(tgrp);

        rb_male.setOnAction(e -> {
            if(rb_male.isSelected()){int maleContact = 1;}
        });
        rb_female.setOnAction(e -> {
            if(rb_female.isSelected()){int maleContact = 0;}
        });

        //create combo box and add items as an observable list
        String[] x = {"Home Address", "Work Address"};
        ComboBox cbo = new ComboBox(FXCollections.observableArrayList(x));
        //cbo.setEditable(false);
        cbo.setValue("Home Address");

//        cbo.setOnAction(e -> {/**____________***/;});
        //set imageBox rectangle action
        //click in it, choose image, file, its displayed?
        //fc is an import or not?
        //setOnMouseClicked should work for any node or scene, why not this rect
        /*imageBox.setOnMouseClicked((MouseEvent e) -> {
            fc.setTitle("Open Image File");
            fc.setInitialDirectory(new File("."));
            fc.getExtensionFilters().addAll(jpgExtension, pngExtension, allExtension);
            fc.setSelectedExtensionFilter(jpgExtension);

            File picture = fc.showOpenDialog(primaryStage);
            if (picture != null){
                rootPane.getChildren().remove(imageBox);
                contact.setImageFile(picture.getName());

                Image userImage = new Image(picture.getName());
                ImageView userView = new ImageView(userImage);

                rootPane.getChildren().add(userView);
            }
        });*/
        GridPane rootPane = new GridPane();        

        rootPane.add(new Label("First Name"), 1, 1);
        rootPane.add(tf_contactFirst, 1, 2);
        rootPane.add(new Label("Last Name"), 2, 1);
        rootPane.add(tf_contactLast, 2, 2);
        rootPane.add(new Label("Sex"), 3, 1);
        rootPane.add(rb_female, 3, 2);
        rootPane.add(rb_male, 3, 3);       
        rootPane.add(new Label("Spouse's First Name"), 1, 4);
        rootPane.add(tf_spouseFirst, 1, 5);
        rootPane.add(new Label("Spouse's Last Name"), 2, 4);
        rootPane.add(tf_spouseLast, 2, 5);
        rootPane.add(cbo, 1, 6);
        rootPane.add(new Label("Address Street"), 1, 7);
        rootPane.add(tf_street, 1, 8);
        rootPane.add(new Label("City"), 1, 9);
        rootPane.add(tf_city, 1, 10);
        rootPane.add(new Label("State"), 2, 9);
        rootPane.add(tf_state, 2, 10);
        rootPane.add(new Label("Zip Code"), 3, 9);
        rootPane.add(tf_zip, 3, 10);
        rootPane.add(imageBox, 4, 1 );

        //Label label = new Label();
        rootPane.add(new Label("Notes"), 1, 11);
        rootPane.add(ta_notes, 1, 12);

        rootPane.add(bt_cancel, 2, 13);
        rootPane.add(bt_save, 3, 13);
        rootPane.add(bt_openContact, 1, 13);

        //scene = window (isn't it just easier if someon mentions that?)
        Scene scene = new Scene(rootPane, 1000, 500);

        primaryStage.setTitle("Address Book");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
    public static void main(String[] args) {
            launch(args);
    }
    public void saveContact(File file) throws FileNotFoundException, Exception{ //declaration
                //this code might cause a FileNotFoundException
                //if it does it creates an exception object of the above type
        try{
                    //PrintWriter output = new PrintWriter (file);
                    PrintStream output = new PrintStream(file);
                    output.println(tf_contactFirst.getText());
                    output.println(tf_contactLast.getText());
                    output.println(tf_spouseFirst.getText());
                    output.println(tf_spouseLast.getText());
                    output.println(tf_street.getText());
                    output.println(tf_city.getText());
                    output.println(tf_state.getText());
                    output.println(tf_zip.getText());
                    output.close();
                }
                //what do do with exception
                //here the catch clause with create another exception
                //that is passed the result of the getMessage() method from the original exception
        catch(FileNotFoundException e){
                    throw new Exception(e.getMessage());
                }
    }

//read same text file you save too
    public void openContact (File file) throws FileNotFoundException, Exception{
        try{
            Scanner read = new Scanner(file);     
            while(read.hasNextLine()){
                //how is a blank field recognized, how are two or three
                //consecutive tokens handled
                //how do I save the imageFileName
                 tf_contactFirst.setText(read.nextLine());
                 tf_contactLast.setText(read.nextLine());
                 //tf_contactGender.setText(read.nextLine());
                 tf_spouseFirst.setText(read.nextLine());
                 tf_spouseLast.setText(read.nextLine());
                 //tf_spouse_gender.setText(read.nextLine());
                 tf_street.setText(read.nextLine());
                 tf_city.setText(read.nextLine());
                 tf_state.setText(read.nextLine());
                 tf_zip.setText(read.nextLine());
                 //ta_notes.setText(read.nextLine());
            }
        }
        catch(FileNotFoundException e){
                    throw new Exception(e.getMessage());
        }
    }
}

Answer 1

您的代码有几个问题会导致问题。

首先，setOnAction() 方法中 bt_openContact 的 lambda 语句不正确。 openContact() 方法实际上从未被调用过。

您可以通过直接传递新的EventHandler 来纠正此问题：

    bt_openContact.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent event) {
            try {
                openContact(file);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

或者使用格式正确的 lamda 语句：

    bt_openContact.setOnAction(event -> {
        try {
            openContact(file);
        } catch (Exception e) {
            e.printStackTrace();
        }
    });

看来你试图同时做这两个。 :)

---

还要注意catch 块。您的代码只是调用f.getMessage()，它返回一个String。但您实际上并没有对 String 进行任何操作，因此即使有错误，您也不会看到它们。

相反，您应该调用 f.printStackTrace() 以实际将任何异常打印到控制台。

无关注意：请查看Java Naming Conventions并坚持使用。

Answer 2

Zephir 的回答完全正确。

回答有关提示和指导的问题：

1. 总是，如果可能的话，想“为什么会在这里？有原因吗？我需要它吗？” - 这有望防止死代码，如：“catch(Exception f){f.getMessage( );} "

2. 了解如何使用调试器。

3. 您似乎正试图弄清一种编程语言的工作原理，并且您之前可能对其他编程语言有一定的经验。每当您尝试此操作时，最好遵循学习路径，例如 https://docs.oracle.com/javase/tutorial/

上提供的路径

这一点尤其重要，因为您在不同编程语言方面的经验越多，就越会开始看起来相同，而实际上它们完全不同。花 3 个小时做这些简单的教程，这样你就可以免去几天的挫败感，试图弄清楚到底发生了什么。

5. 出于某种原因，这在我看来就像有人试图直接在记事本或某些文本编辑软件中编写代码。 不要。使用 IDE（netbeans、eclipse 等）。它们带有格式化工具和调试器，可以让您在比我写这个答案的时间更短的时间内找到诸如此类的简单问题。