Android Utililty Methods String Pad from Left

if (isBlank(str))
    return "";
int j = str.length();
for (int i = j; i < length; i++) {
    str = "0" + str;
return str;

if (width < 0)
    throw new IllegalArgumentException("width must be > 0");
if (width < padding.length)
    return padding[width];
char[] out = new char[width];
for (int i = 0; i < width; i++)
    out[i] = ' ';
return String.valueOf(out);
...

if (input.length() > size) {
    throw new IllegalArgumentException(
            "input must be shorter than or equal to the number of spaces: "
                    + size);
StringBuilder sb = new StringBuilder();
for (int i = input.length(); i < size; i++) {
    sb.append(" ");
...

if (toPad == null)
    toPad = "";
while (toPad.length() < targetLength) {
    toPad = padLetter + toPad;
return toPad;