Question

I am using strings for concat operations. I want to use stringbuffer/stringbuilder as they are more effective.

Original code:

List<BDDObject> childlist; 
String newassetReferenceType = new String();

for (int i = 0; i < childlist.size(); i++)
{
newassetReferenceType = ((String) childlist.get(i).getValue(IDDConstants.IDD_COMPOUND_ASSET_REF_TYPE_NAME)).toLowerCase().trim().concat(((String) childlist.get(i).getValue(
IDDConstants.IDD_COMPOUND_ASSET_REF_VALUE)).trim());

}

SO I tried to change it as
Changed code:

List<BDDObject> childlist; 
StringBuffer newassetReferenceType = new StringBuffer();

for (int i = 0; i < childlist.size(); i++)
{
newassetReferenceType = ((String) childlist.get(i).getValue(IDDConstants.IDD_COMPOUND_ASSET_REF_TYPE_NAME)).toLowerCase().trim().append(((String) childlist.get(i).getValue(
IDDConstants.IDD_COMPOUND_ASSET_REF_VALUE)).trim());

}

Now there is an error that trim() and toLowerCase() methods can not be used. But I have to use them anyhow. Can somebody tell me how to get the advantage of trim() and toLowerCase()and still use StringBuffer.

Answer 1

Your solution should work just fine. I think your parentheses are just a little bit off. You should perform trim() and toLowerCase() operations on the strings before appending them to your StringBuffer.

I rewrote your code to illustrate the concept, using proper parenthesization. Feel free to reformat it and put it in one line, but I think this way it is more readable and less prone to mistakes.

List<BDDObject> childlist; 
StringBuffer newassetReferenceType = new StringBuffer();

for (int i = 0; i < childlist.size(); i++)
{
    var value1 = (String) childlist.get(i).getValue(IDDConstants.IDD_COMPOUND_ASSET_REF_TYPE_NAME);
    var value2 = (String) childlist.get(i).getValue(IDDConstants.IDD_COMPOUND_ASSET_REF_VALUE);

    newassetReferenceType.Append(value1.toLowerCase().trim())
    .append(value2.trim());
 }