How to put the right encoding?

Question

Java

Hello! here is the code:

if (Com.equals("")) {

                    } else {
                        Runtime runtime = Runtime.getRuntime();
                        Process proc = runtime.exec(Com);
                        InputStream process = proc.getInputStream();
                        BufferedInputStream buf = new BufferedInputStream(process);
                        int i;

                        String str = "";

                        while((i = buf.read())!= -1){

                            //System.out.print((char)i);

                            str = str + (char)i;
                            str = str.replace("\\", "/");
                            str = str.replace("<", "");
                            str = str.replace(">", "");
                        }

Cyrillic is displayed incorrectly, how to fix it?