Java Utililty Methods Matrix to String

StringBuilder sb = new StringBuilder("(");
for (double[] rawA : A)
    sb.append(Arrays.toString(rawA)).append(',');
sb.delete(sb.length() - 1, sb.length()).append(')');
return sb.toString();

final StringBuffer buffer = new StringBuffer(ARRAY_OPEN_TAG);
for (int i = 0; i < array.length; i++) {
    final StringBuffer tempBuffer = new StringBuffer(Arrays.toString(array[i]));
    buffer.append(tempBuffer.substring(1, tempBuffer.length() - 1));
    buffer.append(ARRAY_SEPARATOR);
buffer.append(ARRAY_CLOSE_TAG);
return buffer.toString();
...

StringBuffer buf = new StringBuffer();
buf.append("row num = word num=" + data.length + "\n");
if (data.length > 0)
    buf.append("col num = doc num = " + data[0].length + "\n");
for (int c0 = 0; c0 < data.length; c0++) {
    double[] row = data[c0];
    buf.append(Arrays.toString(row)).append("\n");
return buf.toString();

StringBuilder sb = new StringBuilder();
sb.append("{");
for (int i = 0; i < partition.length; i++) {
    sb.append(" " + Arrays.toString(partition[i]));
sb.append(" }");
return sb.toString();

StringBuilder result = new StringBuilder("[");
for (int i = 0; i < a.length; i++) {
    result.append(Arrays.toString(a[i]));
    if (i < a.length - 1)
        result.append(',');
result.append(']');
return result.toString();
...

StringBuilder builder = new StringBuilder();
builder.append("[");
if (matrix.length > 0) {
    builder.append(Arrays.toString(matrix[0]));
    for (int i = 1; i < matrix.length; ++i) {
        builder.append(", ").append(Arrays.toString(matrix[i]));
builder.append("]");
return builder.toString();

String s = "{";
for (int i = 0; i < arr.length; i++) {
    if (i == arr.length - 1)
        s += Arrays.toString(arr[i]);
    else
        s += Arrays.toString(arr[i]) + ", ";
s += "}";
...