public StringFormat(int maxCh, int justn) {
		switch(justn) {
		case JUST_LEFT:
		case JUST_CENTRE:
		case JUST_RIGHT:
			this.just = justn;
			break;
		default:
			throw new IllegalArgumentException("invalid justification arg.");
		}
		if (maxCh < 1) {
			throw new IllegalArgumentException("maxChars must be positive.");
		}
		this.maxChars = maxCh;
	}