Java使用文本文件中的一段代码

Question

I am currently trying to figure something out. For my world editor I want my program to read a text file and use its content as code material. I've already made a decent file reader but now I've got a problem. In the console I am getting the right output, the file has only one line that says:

this.makeGrass(new Vector3f(0, 1, 2));

this is actually part of a code that tells my program to render a specific object to the scene, in this case it's a grass model. However instead of just printing this information to the console with

System.out.println(aryLines[i]);

I want to be able to use the information stored on the .txt file so I can actually add it to my rendering code. The entire method that prints the lines on the text file to the console is:

     public void TextOutput()
     {
        String file_name = "C:/Text.txt";

        try
        {
            StoreCoords file = new StoreCoords(file_name);
            String[] aryLines = file.OpenFile();

            int i;
            for (i = 0; i < aryLines.length; i++)
            {
                System.out.println(aryLines[i]);
            // !! How to use the information as part of my code ??
            }
        } catch(IOException e)
        {
            System.out.println(e.getMessage());
        }
     }

I hope you understand what I want: The content of my text file is a piece of code that I want to use further instead of having it just print to the console, I'm sure this is possible but I wouldn' know how.

Answer 1

As Java is a compiled language, you'd have to recompile at runtime and I am not sure that is even possible. If I were you, I'd hardcode in my own commands. You want to call a function called makeGrass, hardcode it in. Maybe in your text file you can have this:

    makeGrass:0,1,2

Then have this right after the println:

    if(aryLines[i].startsWith("makeGrass:")) {
            String Arguments = aryLines[i].substring(aryLines[i].indexOf(":")+1, aryLines[i].length());
            ArgArray = Arguments.split(",");
            this.makeGrass(new Vector3f(Double.parseDouble(ArgArray[0]), Double.parseDouble(ArgArray[1]), Double.parseDouble(ArgArray[2])));
    }

I'm going to leave my answer like this, assuming you are an experienced programmer. If I am wrong feel free to ask and I will explain it to you. I can also explain how to modify it to add different commands if you want.

Also, this is rather unsafe because if the input is in the wrong format it will crash the app. If you plan on letting users edit the file, then I can show you how to add on safeties.

Hope this helped, Joseph Meadows

Answer 2

Okay, thanks to Joseph Meadows for the hint, I'm doing the following thing, right after the println statement I've added the code provided by him. To make ArgArray work I had to put String[] before it and also I had to create a new constructor in my Vector3f class to match the Double.parseDouble thingy..

public void TextOutput()
     {   
        String file_name = "C:/Users/Server/Desktop/textText.txt";

        try
        {           
            StoreCoords file = new StoreCoords(file_name);
            String[] aryLines = file.OpenFile();

            int i;
            for (i = 0; i < aryLines.length; i++)
            {
                System.out.println(aryLines[i]);    

                 if(aryLines[i].startsWith("makeGrass:")) {
                        String Arguments = aryLines[i].substring(aryLines[i].indexOf(":")+1, aryLines[i].length());
                        String[] ArgArray = Arguments.split(",");

                        this.makeGrass(new Vector3f(Double.parseDouble(ArgArray[0]), 
                                                    Double.parseDouble(ArgArray[1]), 
                                                    Double.parseDouble(ArgArray[2])));
                }
            }
        } catch(IOException e)
        {
            System.out.println(e.getMessage());
        }
     }

my original Vector3f constructor is:

public Vector3f(float x, float y, float z)
    {
        this.m_x = x;
        this.m_y = y;
        this.m_z = z;
    }

and to make the code in the TextOutput method work I've added another constructor right below the original one..

public Vector3f(double parseDouble, double parseDouble2, double parseDouble3) {
        this.m_x = (float) parseDouble;
        this.m_y = (float) parseDouble2;
        this.m_z = (float) parseDouble3;
    }

Now everything works great, the console gives me the apropriate statement

makeGrass:0,1,2

and the rendering system creates the grass model at the apropriate coordinates, the only thing I want to change now is that I don't have to add an additional constructor to the Vector3f class, I'm sure I'll figure that out too.

In the picture provided in this link you can see exactly what's going on:

http://www.pic-upload.de/view-27720774/makeGrassEx.png.html

As you can see, the content of the text file is printed out in the console (the numbers below is the fps counter) and the coordinates provided by the text file are interpreted correctly, two grass models being displayed at the respective coordinates which is exactly what I wanted!

Thanks again for your help Joseph Meadows, this is exactly what I was looking for!

Answer 3

I am not sure if you solved this yet, but you did not need the second constructor. I was unsure of the data type you were using for the coordinates, and I assumed you use doubles because that is what I have grown accustomed to using.

In actuality, all types can be parsed from a string. Look here:

    this.makeGrass(new Vector3f(Double.parseDouble(ArgArray[0]), 
                                Double.parseDouble(ArgArray[1]), 
                                Double.parseDouble(ArgArray[2])));

This right now is turning the string into a double. That is what

    Double.parseDouble();

does.

It looks like you are using floats though, so you can always just use the float parsing method:

    Float.parseFloat("String");

That would result with this:

    this.makeGrass(new Vector3f(Float.parseFloat(ArgArray[0]), 
                                Float.parseFloat(ArgArray[1]), 
                                Float.parseFloat(ArgArray[2])));

Sorry for the late response, and you are surely welcome for the help. I just love being useful!