Memory Overflow from String Concatenation in Loop

1. Using += in loop to build strings: str += item creates new object each iteration
2. String concatenation inside tight loop processing millions of items
3. No buffer/accumulator, just repeatedly building larger strings
4. Serialization to JSON or XML using simple string concatenation
5. Log message building with repeated concatenation

Use StringBuilder (Java) or StringBuffer for accumulation: StringBuilder sb = new StringBuilder(); sb.append(item). In loops: always use StringBuilder. For JSON: use library like Jackson, Gson. For logging: use parameterized messages: log.info("Item: {}", item) not "Item: " + item. Test with large data: if memory spikes, likely concatenation issue.