Format Standards - Java

1. Add Spaces Around Keywords and Parentheses

Reserved words such as if, for, while, switch, and do must have a space before and after parentheses. Operators must also have spaces on both sides:

// Correct
if (xmlFile == null || !xmlFile.exists()) {
    return;
}

// Wrong
if(xmlFile==null||!xmlFile.exists()){
    return;
}

2. Brace Style

Empty block: {} on one line, no line break.
Non-empty block: opening brace on the same line (no line break before it), line break after opening brace, line break before closing brace, no line break after closing brace if followed by else.

// Correct
public void calculateCountOfStock() {}

public void calculateCountOfStock() {
    doSomething();
}

// if-else
if (condition) {
    doA();
} else {
    doB();
}

3. Spaces Around Operators

// Correct
int result = a + b;
return (a + b > 0) ? "student" : "teacher";

// Wrong
int result=a+b;

4. Space After Comma in Method Arguments

// Correct
invokeMethod("a", "b", "c");

// Wrong
invokeMethod("a","b","c");

5. Method Length Must Not Exceed 50 Lines

Long methods are hard to unit test and maintain. Aim for one method, one responsibility.

6. Avoid Complex Expressions in if Conditions

No more than two logical expressions in a condition. Extract longer conditions into a dedicated method:

// Correct
if (shouldDoSomething(a, dim)) {
    doSomething();
}

boolean shouldDoSomething(int a, Dimension dim) {
    return a > -1 && a != 1 && dim.width > 0 && dim.height > 0;
}

// Wrong
if (a > -1 && a != 1 && dim.width > 0 && dim.height > 0) {
    doSomething();
}

7. No Access Modifiers on Interface Methods and Fields

Interface methods and fields should not have public or other access modifiers — keep them concise:

// Correct
interface Animal {
    int countOfLegs();
}

// Wrong
interface Animal {
    public int countOfLegs();
}

8. JSON Output Format

When outputting JSON from Java code, always use the standard approach. Use JSONArray for arrays:

// Wrong
{a:"bb"};
{'a':"bb"};

// Correct
{"aa":"bb"};

// Use JSONArray for arrays (do not put a Java native array into JSONObject)
JSONObject jo = JSONObject.create();
JSONArray ja = new JSONArray();
ja.put("aaa").put("bbb").put("ccc");
jo.put("names", ja);

9. Use StringUtils.EMPTY for Empty Strings

// Wrong
if (name == null) {
    return "";
}

// Correct
if (name == null) {
    return StringUtils.EMPTY;
}

Use StringUtils.isEmpty() to check whether a string is empty:

// Wrong
if ("".equals(name)) { ... }

// Correct
if (StringUtils.isEmpty(name)) { ... }

10. Use GeneralUtils.objectToString to Convert Objects to Strings

// Wrong (may throw NullPointerException)
String result = key.toString();

// Correct
String okStr = GeneralUtils.objectToString(key);

11. Write equals and hashCode Manually — Do Not Use IDE Auto-Generation

IDE-generated templates are difficult to maintain correctly when new fields are added or special comparisons are required:

// Correct approach
public boolean equals(Object obj) {
    return obj instanceof MyObject
            && ComparatorUtils.equals(this.src, ((MyObject) obj).src)
            && this.isOverflowX() == ((MyObject) obj).isOverflowX()
            && this.isOverflowY() == ((MyObject) obj).isOverflowY();
}

Format Standards