运行可执行JAR时JavaFX应用无法加载图片的问题

问题现象 #

开发JavaFX应用时，在IntelliJ中运行完全正常，但打包成可执行JAR后，加载英雄图片时抛出空指针异常。奇怪的是应用图标能正常加载，仅英雄图片加载失败。

相关代码 #

创建英雄ImageView的方法 #

private ImageView createChampionImageView(Champion champion)
{
    ImageView imageView = new ImageView("/images/champions/" + champion.getName().toLowerCase().replaceAll("[. ]", "") + ".png");
    imageView.setFitHeight(60);
    imageView.setFitWidth(60);
    RoundCorners.setRoundedCornerImageView(imageView);
    return imageView;
}

调用ImageView创建方法的fillChampionsPane() #

public void fillChampionsPane()
{
    if (championsPageParser.champions() == null)
        return;
    ArrayList<Champion> champions = championsPageParser.champions();
    for (Champion champion : champions)
    {
// 此方法内部会调用createChampionImageView
        addToTilePane(champion);
    }
}

触发fillChampionsPane()的setChampionsParserUGG() #

@FXML
private void setChampionsParserUGG()
{
    JavaLeagueBuilds.chosenPage = U_GG;
    JavaLeagueBuilds.getInstance().switchToLoading();
    CompletableFuture.runAsync(() -> ChampionsScene.getInstance().setChampionsPageParser(new HtmlChampionsUGGParser()))
            .thenRun(() -> Platform.runLater(() -> {
                ChampionsScene.getInstance().fillChampionsPane();
                JavaLeagueBuilds.getInstance().switchToChampions();
            }));
}

报错信息 #

首次运行可执行JAR时的报错：

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException: Cannot invoke "java.net.URL.toString()" because the return value of "java.lang.Class.getResource(String)" is null
at me.trup10ka.jlb.controllers.ChampionsScene.createChampionImageView(ChampionsScene.java:138)
at me.trup10ka.jlb.controllers.ChampionsScene.addToTilePane(ChampionsScene.java:91)
at me.trup10ka.jlb.controllers.ChampionsScene.fillChampionsPane(ChampionsScene.java:75)
at me.trup10ka.jlb.controllers.MainScene.lambda$setChampionsParserUGG$3(MainScene.java:48)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:185)
at java.base/java.lang.Thread.run(Thread.java:833)

尝试使用getClass().getResource()后的报错：

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException: Cannot invoke "java.net.URL.toExternalForm()" because the return value of "java.lang.Class.getResource(String)" is null
at me.trup10ka.jlb.controllers.ChampionsScene.createChampionImageView(ChampionsScene.java:141)
at me.trup10ka.jlb.controllers.ChampionsScene.addToTilePane(ChampionsScene.java:94)
at me.trup10ka.jlb.controllers.ChampionsScene.fillChampionsPane(ChampionsScene.java:78)
at me.trup10ka.jlb.controllers.MainScene.lambda$setChampionsParserUGG$3(MainScene.java:48)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:185)
at java.base/java.lang.Thread.run(Thread.java:833)

Process finished with exit code 0

已尝试的解决方法 #

• 使用getClass().getResource()加载图片资源
• 使用getResourceAsStream()加载图片资源
  以上方法均未解决问题。

内容的提问来源于stack exchange，提问作者Trupka