substring 导致内存溢出

import java.util.ArrayList;
import java.util.List;

public class TestSubstring {

public static void main(String[] args) {

List<String> handler =new ArrayList<String>();
int j = 0;

for (int i = 0; i < 1000; i++) {
j++;
HugeStr h = new HugeStr();
handler.add(h.getSubString(1,5));
System.out.println(j);
}
}

static class HugeStr{

private String str=new String(new char[100000]);

public String getSubString(int begin,int end){

return str.substring(begin, end);
}
}

static class ImprovedHugeStr{

private String str=new String(new char[100000]);

public String getSubString(int begin,int end){

return new String(str.substring(begin, end));
}
}
}