How To Use Java Formatter & Validator
📝 Step 1: Enter Java Code
Paste your Java source code in the input area. Supports classes, methods, and various Java constructs.
⚙️ Step 2: Choose Java Version
Select your Java version (8, 11+, or 17) for accurate validation of version-specific syntax.
🔧 Step 3: Format or Validate
Click "Format Java" to beautify your code with proper indentation. Click "Validate Java" to check for syntax errors.
📋 Step 4: Copy or Download
Use the "Copy" button to copy formatted Java to clipboard, or "Download" to save as .java file.
💡 Pro Tips
- Use the Sample button to load an example Java class
- Validation checks for: missing semicolons, brackets, correct syntax, and Java keywords
- Formatting preserves comments and string literals
- Works with inner classes, lambdas (Java 8+), and modules (Java 9+)
🔍 Example
// Before formatting:
public class Calculator {
public int add(int a,int b){
return a+b;
}
public static void main(String[] args) {
Calculator calc=new Calculator();
System.out.println(calc.add(5,3));
}
}
// After formatting:
public class Calculator {
public int add(int a, int b) {
return a + b;
}
public static void main(String[] args) {
Calculator calc = new Calculator();
System.out.println(calc.add(5, 3));
}
}
Frequently Asked Questions
What Java versions are supported? ▼
We support Java 8, Java 11, and Java 17. Each version has its own validation rules for keywords, APIs, and syntax features like lambdas (Java 8), var (Java 10), and switch expressions (Java 14).
Does it validate all Java syntax? ▼
The validator checks for common syntax errors including: missing semicolons, unmatched braces/parentheses, incorrect method declarations, invalid modifiers, and basic semantic rules. It's designed for standard Java classes and methods.
What formatting options are available? ▼
The formatter adds proper indentation (4 spaces), line breaks after braces, consistent spacing around operators, aligns annotations, and preserves comments and string literals. It makes your Java code clean and readable following standard conventions.
Can I format multiple classes? ▼
Yes! The tool handles multiple classes in one file. Each class is formatted independently while maintaining proper nesting for inner classes.
Is my Java code secure? ▼
Absolutely. All processing happens in your browser. Your Java code is never sent to our servers. It's completely client-side for privacy and security.
What are common Java errors it detects? ▼
Common errors include: missing semicolons, mismatched braces, incorrect method signatures, invalid import statements, wrong modifier order, and missing return types.
Does it work with annotations? ▼
Yes, annotations are fully supported. The formatter preserves them and applies proper indentation. Validation checks for correct annotation syntax and placement.
How accurate is the validation? ▼
The validator catches most syntax errors but may not catch semantic errors like type mismatches or missing imports. It's excellent for quick syntax checking and code beautification.