StringBuilder.append() With Single-Character String
ID |
java.stringbuilder_append_char_as_string |
Severity |
low |
Remediation Complexity |
trivial |
Remediation Risk |
low |
Remediation Effort |
low |
Resource |
Efficiency |
Language |
Java |
Tags |
best-practice, efficiency |
Description
Reports calls to StringBuilder.append() or StringBuffer.append() where the argument is a single-character String literal (e.g., append("x")). The char overload append('x') should be preferred for better performance.
Rationale
When append(String) is called with a single-character string, the JVM must resolve the String object, obtain its internal character array, and copy the single character. The append(char) overload bypasses this overhead entirely, appending the character directly to the internal buffer. In tight loops or heavily used string-building code, this micro-optimization adds up.
// Bad -- single-char string literal
sb.append(",");
sb.append("\n");Remediation
Replace the single-character String literal with the corresponding char literal.
// Good -- char literal
sb.append(',');
sb.append('\n');