Refactoring Practices and Tools for Java Code

Before diving into refactoring, the article discusses basic questions such as the definition of refactoring—modifying code without changing external behavior to improve internal structure—and whether refactoring and performance optimization are the same.

It then outlines the purposes of refactoring (improving structure, readability, extensibility, and reducing risk), appropriate timing (after repeated copy‑paste, during code review, planned work, or when production issues arise), and situations where refactoring should be avoided.

The core part lists common refactoring scenarios and techniques, including handling overly long parameter lists by extracting parameter objects or using functions, simplifying conditional logic with guard clauses, extracting functions, merging conditions, applying strategy or factory patterns, and dealing with shotgun surgery and dead code.

public List<WorkAuditDetail> workCal(Long groupID, Long orgID, Long startDate, Long endDate, Long month, List<Long> employeeIdList) { /* ... */ }

Another example shows how guard clauses replace nested if‑else structures for clearer validation logic.

public static String checkEntryOptimized(boolean hasTicket, int age, boolean hasID, boolean isEvening) {
    if (!hasTicket) {
        return "您需要先买票。";
    }
    if (age < 18) {
        return "您必须年满18岁才能参加此活动。";
    }
    if (isEvening && !hasID) {
        return "请携带身份证参加晚间活动。";
    }
    return "欢迎参加本次活动！";
}

Finally, the article reviews refactoring tools: built‑in IntelliJ IDEA features (rename, extract method, inline, change signature, extract interface/class, safe delete, etc.) and additional plugins such as Lombok, Alibaba Java Coding Guidelines, CodeGlance, and SequenceDiagram, along with guidance on scanning for unused code.

The conclusion reminds readers to consider the purpose and boundaries of refactoring and to choose the appropriate approach for each situation.