如何克隆（）StringBuilder

Question

Is there some ways how I could clone StringBuilder ? I am reading files by bits then convert these bits to ASCII chars after that I collect chars into String builder and when I have for example 8 chars I put that String Builder object into Array List. Then I clean it and again do the same. However I can't create new string builder because of memory and I can't do changes to that String builder because in Array List also that builder changes.

So I think I have to clone that String Builder and put it into Array List. There is just one problem String Builder don't have clone(). So what is my alternatives ?

Maybe someone could give some ideas what is neat way to do this considering about performance and memory.

ArrayList characters = new ArrayList(); int counter = 0;

StringBuilder sb = new StringBuilder(blockSize-1);

while (mbb.hasRemaining()) {   

char charAscii = (char)mbb.get();


    counter++;
    charCounter++;

     if (counter == blockSize){

        sb.append(charAscii);
        characters.add(sb);//sb.toString()
        sb.delete(0, sb.length());
        counter = 0;

    }else{

        sb.append(charAscii);

     }

 if(!mbb.hasRemaining()){
    characters.add(sb);
}



}
fc.close();
return characters;

Answer 1

If you don't have the memory to create a new StringBuilder , then you don't have the memory to create a new StringBuilder , and cloning wouldn't change that. The only real way to copy a StringBuilder is new StringBuilder(myBuilder) , or something equivalent.

If you're getting OutOfMemoryException , you'll need to either get more memory, or find some other way to reduce memory consumption.

Answer 2

You can clear StringBuilder object by:

1.

sb.delete(0, sb.length()) 

2.

sb = null;
sb = new StringBuilder();

For performance, 1. is the better option. But you cannot clone it anyway. For more info about clone see

• Shallow copy and Deep Copy
• Clone