public static void ALS_branch(String num, String filepath, String downloadpath, String []paras, Scanner scanner){
		String line="", result = "";
		int item=0;
		System.out.println("Please choose the light status you want to test: 1=dark, 2=bright, 0=return:");
		System.out.println("If you choose to test the dark status, please keep blocking the light before you press 1 until you see the instruction.");
		line=scanner.nextLine();
		while(!(line.equals("0"))){
			while ((!(line.equals("1")))&&(!(line.equals("2")))&&(!(line.equals("0")))){
				System.out.println("Error input! ");
				System.out.println("Please choose the light status you want to test: 1=dark, 2=bright, 0=return:");
				line=scanner.nextLine();
			}
			if (line.equals("0")){
				break;
			}
			item = Integer.parseInt(line);
			switch(item){
			case 1:
				ALS_dark.serialcomm(num);
				ALS_dark.fileprocess(downloadpath, filepath, paras);
				break;
			case 2:
				ALS_bright.serialcomm(num);
				ALS_bright.fileprocess(downloadpath, filepath, paras);
				break;
			}
			System.out.println("Please choose the light status you want to test: 1=dark, 2=bright, 0=return:");
			line=scanner.nextLine();
		}
	}