JFX2中實現Combox顯示圖片

 直接貼圖：

  在寫國旗顯示代碼時忘記一點，每個節點只有一個父節點！之前就是當選中其中一項時，只有選中項有國旗，而下面選項中的國旗消失了，只有重新生成一次拷貝才行，原理弄清楚對寫代碼是很重要的。

 

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package regist;

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.VPos;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.ColumnConstraints;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.util.Callback;

/**
 *
 * @author Administrator
 */
public class Regist extends Application {

    public static final java.util.Map<String,ImageView> flagmap = new java.util.HashMap<String, ImageView>();
    public static  String[] countries;
    public static Label[] country_label;
    //public static ;
    static{
        countries = new String[]{"cn","de","ir","jp"};
        for(String s : countries){
            final ImageView img = new ImageView(new Image(Regist.class.getResourceAsStream(s+".png")));
            flagmap.put(s, img);
        }
        country_label = new Label[]{
            new Label("中國",flagmap.get("cn")),
            new Label("德國",flagmap.get("de")),
            new Label("伊拉克",flagmap.get("ir")),
            new Label("日本",flagmap.get("jp"))
        };
    }
    private void showRegistDialog(){
        Stage registWin = new Stage();
        HBox hb = new HBox();
        GridPane pane = new GridPane();
        ColumnConstraints cons1 = new ColumnConstraints(140);
        ColumnConstraints cons2 = new ColumnConstraints(240);
        ColumnConstraints cons3 = new ColumnConstraints(40);
        pane.getColumnConstraints().addAll(cons1,cons2,cons3);
        HBox.setMargin(pane, new Insets(20,20,20,20));
        hb.getChildren().add(pane);
        //定義標籤
        Label l_name = new Label("姓名：");
        Label l_sex = new Label("性別：");
        Label l_country = new Label("國籍：");
        //放置標籤
        pane.add(l_name, 0, 0);
        l_name.setId("l_name");
        pane.add(l_sex, 0, 1);
        pane.add(l_country, 0, 2);
        //定義輸入框
        TextField t_name = new TextField("");
        t_name.setPromptText("輸入姓名");
        t_name.setPrefWidth(230);
        t_name.setPrefHeight(32);
        //定義性別項
        javafx.scene.control.ComboBox<String> c_sex = new ComboBox<String>();
        c_sex.getItems().addAll("男","女");
        c_sex.setPrefHeight(32);
        c_sex.setPrefWidth(120);
        //定義國籍
        final ComboBox<Label> c_country = new ComboBox<Label>();
        c_country.setId("country");
        c_country.getStyleClass().add("country");
        c_country.getItems().addAll(country_label);
        c_country.setPrefWidth(120);
        c_country.setPrefHeight(32);
        c_country.setCellFactory(new CountryFactory());
        c_country.getSelectionModel().selectFirst();
        final ImageView l_flag =Regist.flagmap.get("cn");
        final Label image = new Label("g",l_flag);
        c_country.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<Label>(){
            @Override
            public void changed(ObservableValue<? extends Label> arg0, Label arg1, Label arg2) {
                System.out.println("單位個數："+c_country.getItems().size());
                image.setGraphic(arg2.getGraphic());
            }
        });
        pane.add(t_name, 1, 0);
        pane.add(c_sex, 1, 1);
        pane.add(c_country, 1, 2);
        //pane.add(l_flag, 2, 2);
        image.setPrefHeight(32);
        image.setPrefWidth(32);
        pane.add(image , 2, 2);
        pane.setId("scene1");
        hb.setId("bg");
        Scene scene = new Scene(hb,490,120);
        registWin.setScene(scene);
        registWin.show();
    }
    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) {
        showRegistDialog();
    }
}
class CountryCell extends ListCell<Label>{
    public CountryCell(){
    }
    @Override
    public void updateItem(Label item,boolean empty){
        super.updateItem(item, empty);
        if(item==null){
            System.out.println("item爲空");
            return;
        }
        String str = item.getText();
        Label l_c = new Label();
        l_c.setText(str);
        System.out.println("國家："+l_c.getText());
        if(str.equals("中國")){
            ImageView img = new ImageView(Regist.flagmap.get("cn").getImage());//重新生成的圖片，這個很重要
            l_c.setGraphic(img);
        }else if(str.equals("日本")){
            ImageView img = new ImageView(Regist.flagmap.get("jp").getImage());
            l_c.setGraphic(img);
        }else if(str.equals("德國")){
            ImageView img = new ImageView(Regist.flagmap.get("de").getImage());
            l_c.setGraphic(img);
        }else if(str.equals("伊拉克")){
            ImageView img = new ImageView(Regist.flagmap.get("ir").getImage());
            l_c.setGraphic(img);
        }
        this.setGraphic(l_c);
    }
}
class CountryFactory implements Callback<ListView<Label>,ListCell<Label>>{
    @Override
    public ListCell<Label> call(ListView<Label> listview) {
        return new regist.CountryCell();
    }
}