nd4j-common/src/main/java/org/nd4j/util/StringUtils.java
public static String arrayToString(String[] strs) {
        if (strs.length == 0) { return ""; }
        StringBuilder sbuf = new StringBuilder();
        sbuf.append(strs[0]);
        for (int idx = 1; idx < strs.length; idx++) {
            sbuf.append(",");
            sbuf.append(strs[idx]);
        }
        return sbuf.toString();
    }
public static String arrayToString(String[] strs) {
        if (strs.length == 0) { return ""; }
        StringBuilder sbuf = new StringBuilder();
        sbuf.append(strs[0]);
        for (int idx = 1; idx < strs.length; idx++) {
            sbuf.append(",");
            sbuf.append(strs[idx]);
        }
        return sbuf.toString();
    }
Given an array of strings, return a comma-separated list of its elements.
@param strs Array of strings
@return Empty string if strs.length is 0, comma separated list of strings
otherwise