What is transient keyword in Java
💡 Concept: Transient Keyword
The transient keyword in Java marks a field to be skipped during serialization.
📘 Quick Intro
Fields marked as transient are not included in the serialized representation of an object.
🧠 Analogy
Transient is like putting aside some personal items before sending a package, so they are not shipped.
🔧 Technical Explanation
- Transient fields are ignored by Java serialization.
- Useful for sensitive data or temporary states.
- Does not affect deserialization of other fields.
- Transient can be used with any data type.
- Static fields are never serialized, regardless of transient.
🎯 Use Cases
- ✅ Skip sensitive data like passwords during serialization.
- ✅ Avoid serializing temporary or cached data.
- ✅ Reduce serialized object size.
💻 Example: Using transient keyword
import java.io.Serializable;
public class User implements Serializable {
private String username;
private transient String password; // will not be serialized
public User(String username, String password) {
this.username = username;
this.password = password;
}
// getters and setters
}
❓ Interview Q&A
Q1: What does transient do?
A: Prevents field serialization.
Q2: Can transient fields be restored?
A: No, they are null/default after deserialization.
Q3: Can static fields be transient?
A: Yes, but static fields are not serialized anyway.
Q4: When to use transient?
A: For sensitive or temporary data.
Q5: Does transient affect serialization of other fields?
A: No.
Q6: Is transient a keyword or annotation?
A: It is a keyword.
Q7: Does transient work with custom serialization?
A: Yes, but must be handled manually.
Q8: Can final fields be transient?
A: Yes.
Q9: Is transient specific to Java?
A: Yes, in Java serialization.
Q10: What happens to transient fields on deserialization?
A: They get default values (null, 0, false).
📝 MCQs
Q1. What does transient do?
- Includes field
- Prevents field serialization
- Deletes field
- Copies field
Q2. Can transient fields be restored?
- Yes
- No
- Sometimes
- Depends
Q3. Can static fields be transient?
- No
- Yes, but not serialized anyway
- Only static
- Only transient
Q4. When to use transient?
- Always
- Never
- Sensitive or temporary data
- Only final fields
Q5. Does transient affect other fields?
- Yes
- No
- Sometimes
- Depends
Q6. Is transient a keyword or annotation?
- Keyword
- Annotation
- Method
- Class
Q7. Does transient work with custom serialization?
- No
- Yes
- Sometimes
- Never
Q8. Can final fields be transient?
- No
- Yes
- Sometimes
- Never
Q9. Is transient specific to Java?
- No
- Yes
- Sometimes
- Depends
Q10. What happens to transient fields on deserialization?
- Original values
- Default values
- Null
- Error
💡 Bonus Insight
Using transient wisely helps secure sensitive data and optimize serialized objects in Java applications.
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