public static String readFile2(String file) throws IOException{
		//System.out.println("path : " + path + " reading...");
		Watch t = new Watch();t.start();
		System.out.println("read......");	
		String sJSON = "";
		
		Path path = Paths.get(file);
		List<String> text =Files.readAllLines(path,StandardCharsets.UTF_8);
		
		//number of threads
		int threadNumber = 4;
		
		Thread[] array= new Thread[threadNumber];
		int size= text.size();
		str= new String [threadNumber];
		int d = size/threadNumber;
		for (int i=0; i<threadNumber;i++){
			int min = d*i;
			int max = d*(i+1); if(i==threadNumber-1)max=size;
			Thread a = new Thread(new threadReader(i,text,min,max));
			a.start();
			array[i]=a;
		}
		for(Thread is:array){
			try {
				is.join();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				is.interrupt();
			}
		}
		for(String jsonPart : str){
			sJSON += jsonPart;
		}

		t.stop();
		System.out.println("stop ...... "+t.getElapsedTime() +"ms");
		//System.exit(0);
		return sJSON;	
		}