Java Utililty Methods List Concatenate

assert missingParameters != null;
assert separator != null;
if (missingParameters.isEmpty()) {
    return "";
StringBuilder result = new StringBuilder();
for (int i = 0; i < missingParameters.size() - 1; i++) {
    result.append(missingParameters.get(i));
...

StringBuffer concatenatedString = new StringBuffer();
for (String data : input) {
    concatenatedString.append(data);
    concatenatedString.append(delimiter);
return concatenatedString.toString();

StringBuilder concatStr = new StringBuilder();
for (String code : codes) {
    concatStr.append("'" + code + "'" + ",");
return concatStr.toString().replaceAll(",$", "");

StringBuilder sb = new StringBuilder();
if (numbers.size() == 0) {
    return sb.toString();
Number prev = null;
Number current = null;
for (int i = 0; i < numbers.size(); i++) {
    current = numbers.get(i);
...

StringBuffer concatenatedString = new StringBuffer();
for (int i = 0; i < input1.size(); i++) {
    concatenatedString.append(input1.get(i));
    concatenatedString.append("='");
    if (i < input2.size()) {
        concatenatedString.append(input2.get(i));
    concatenatedString.append("'");
...

StringBuffer sb = new StringBuffer();
for (String str : stringList) {
    if (str.contains(delimiter)) {
        throw new IllegalArgumentException(
                "Source name '" + str + "' contains DELIMITER '" + delimiter + "'");
    if (sb.length() == 0) {
        sb.append(str);
...

StringBuffer sb = new StringBuffer();
for (int i = 0, m = _toString.size(); i < m; i++) {
    sb.append(_toString.get(i));
    if ((i + 1) != m) {
        sb.append(_concator);
return sb.toString();
...