由应用程序启动方法中的java.lang.runtimeexception异常引起

Question

I use javaFX without a fxml file needed all time. When I run my app in IDE it works perfectly. Only when I make jar file it does not work. Any help?

error : no such file in res\img\menu_bg.png 

this file is in same folder like whole code

code

public class InputStreamClass {
    private ImageView imgViewBG;
    public InputStreamClass() throws Exception {
        InputStream isBG = Files.newInputStream(Paths.get("res/img/menu_bg.png")); // res/img/menu_bg.png
        Image imgBG = new Image(isBG);
        isBG.close(); // kedze je to InputStream a pracujeme zo suborom tak vzdy ho treba zatvarat 
        this.imgViewBG = new ImageView(imgBG); // pridame img do ImageView
        this.imgViewBG.setFitWidth(1600); // sirka obrasku
        this.imgViewBG.setFitHeight(900); // vyska obrasku
    }
     public ImageView getImageViewBG() {
        return this.imgViewBG;
     }
}

Answer 1

I assume you do not need to write to the image file.

In this case the image should better be included in the jar itself. This prevents issues with paths. Java tries to resolve relative paths relative to the working directory, which often is not the code folder.

By adding the image to the jar file itself you can get the resource using a Class instance, eg

// InputStream isBG = getClass().getResourceAsStream("/res/img/menu_bg.png");
// Image imgBG = new Image(isBG);

Image imgBG = new Image(getClass().getResource("/res/img/menu_bg.png").toExternalForm());

which works independent of the working directory.

This assumes the file is stored as /res/img/menu_bg.png entry in the jar file.

Answer 2

try this: In the same folder as your jar, put another folder name res. Inside the res folder create a folder name img. Inside the img folder put your actually image with the name above.