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Я пытаюсь запустить приложение C на Java, используя ProcessBuilder и .getInputStream() . Что, я думаю, получает вывод этого приложения? Тогда я думаю, мне нужно использовать FileReader, завернутый в BufferedReader? Я не уверен, как подключить процесс и FileReader?

Я перевожу некоторые C (в комментариях):

 void run(){ 
        //FILE *POINTS;
        //I think the above points to the file? so I'm using a InputStream object. 

        private InputStream POINTS;

            //generate octree for this case
            //=============================
            //sprintf(befehl,"%soconv -f %s %s %s "%s" > %sn","",material_file, BlindRadianceFiles_Combined, geometry_file, sun_rad, octree);
            //note I've replaced "befehl" with "cmd".

            String.format(cmd, "%soconv -f %s %s %s "%s" > %sn","",material_file, BlindRadianceFiles_Combined, geometry_file, sun_rad, octree);

            //POINTS = popen(befehl,"r");
            //Info on POPEN in C. For instance, if you wanted to read the output of your program, you'd use popen("program", "r"). On the other hand, if you want to write to its input, you would use popen("program", "w").

            Process process = new ProcessBuilder(cmd).start();
            POINTS = process.getInputStream();

            //while( fscanf( POINTS, "%s", buf ) != EOF )
            //  printf("%s n",buf);
            //pclose(POINTS);

            BufferedReader in = new BufferedReader(new FileReader("<filename>"));

            while ((in = fileReader.readLine()) != null){
                System.out.printf("%s n", buf);
            }
            POINTS.close();
  

ОБНОВЛЕНИЕ: ниже:

Теперь у меня есть следующее, кажется, это имеет смысл? Существует 2 разные программы на C, которые на основе команд генерируют файлы и выполняют некоторые конкретные вычисления.

 void run_oconv_and_rtrace() throws IOException{
    String line;
    String cmd = null;

    //generate octree for this case
    //=============================
    //TODO review how the command is generated and what information is required for this analysis
    cmd = String.format(cmd,"%soconv -f %s %s %s "%s" > %sn","", material_file, BlindRadianceFiles_Combined, geometry_file, sun_rad, octree);

    /* Use the processbuilder to run an external process (ie. Radiance C program).
     * process.getOutputStream(): return the standard input of the external program. (ie. Java writes to Process).
     * process.getInputStream(): return the standard output of the external program. (ie. Jave reads from Process).
     */

    ProcessBuilder builder = new ProcessBuilder(cmd);
    builder.redirectErrorStream(true);                  //adds error stream to inputstream
    Process process = builder.start();

    OutputStream POINTS_FROM_JAVA_TO_C = process.getOutputStream();
    InputStream POINTS_FROM_C_TO_JAVA = process.getInputStream();

    //BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(POINTS_FROM_JAVA_TO_C));
    BufferedReader reader = new BufferedReader(new InputStreamReader(POINTS_FROM_C_TO_JAVA));

    //Read output of Radiance:
    while ((line = reader.readLine()) != null){
        System.out.printf("%s n", buf);
    }

    //////////////////////////


    // run rtrace and calcualte the shading status for this case
    //==========================================================
    //TODO review command
    cmd = null;
    cmd = String.format(cmd, "rtrace_dc -ab 0 -h -lr 6 -dt 0 "%s" < %s > %sn",octree,long_sensor_file[BlindGroupIndex],dir_tmp_filename[NumberOfBlindGroupCombinations]);

    builder = new ProcessBuilder(cmd);
    builder.redirectErrorStream(true);                  //adds error stream to inputstream
    process = builder.start();

    POINTS_FROM_C_TO_JAVA = process.getInputStream();
    reader = new BufferedReader(new InputStreamReader(POINTS_FROM_C_TO_JAVA));

    //Read output of Radiance:
    while ((line = reader.readLine()) != null){
        System.out.printf("%s n", buf);
    }

    //delete files
    //HERE WE NEED TO DELETE THE OCTREE FILES CREATED!

    BlindGroupNumberForThisCombination[NumberOfBlindGroupCombinations]=BlindGroupIndex;
    NumberOfBlindGroupCombinations  ;
}
  

Измените эту строку

 BufferedReader in = new BufferedReader(new FileReader("<filename>"));
  

к этому:

 BufferedReader in = new BufferedReader(new InputStreamReader(POINTS));