Why is if-else
Slower than switch
in Java (When Using Strings)?
The performance difference between if-else
and switch
comes down to how Java processes conditions:
if-else
checks each condition sequentially (one by one).switch
uses a lookup mechanism (hashing and jump tables), which is optimized for performance.
1. if-else
Evaluates Conditions One by One
When using if-else
, Java must check each condition separately until it finds a match.
Example: if-else
String Comparison
public class IfElseExample {
public static void main(String[] args) {
String day = "Friday";
if (day.equals("Monday")) {
System.out.println("Start of the week!");
} else if (day.equals("Tuesday")) {
System.out.println("Regular workday.");
} else if (day.equals("Wednesday")) {
System.out.println("Midweek.");
} else if (day.equals("Thursday")) {
System.out.println("Almost there.");
} else if (day.equals("Friday")) {
System.out.println("Weekend is coming!");
} else {
System.out.println("Weekend!");
}
}
}
How Java Executes This:
- First, it checks
day.equals("Monday")
→ false - Then, it checks
day.equals("Tuesday")
→ false - Then, it checks
day.equals("Wednesday")
→ false - Then, it checks
day.equals("Thursday")
→ false - Finally, it checks
day.equals("Friday")
→ true, so it executes that block.
🚨 Problem: If the matching case is at the end, Java must evaluate multiple conditions, making execution slower.
2. switch
Uses a More Optimized Approach
When using a switch
statement, Java does not check each case sequentially. Instead:
- It computes the
hashCode()
of the string. - It uses a lookup mechanism (jump table or hash table) to find the matching case directly.
Example: switch
String Comparison
public class SwitchExample {
public static void main(String[] args) {
String day = "Friday";
switch (day) {
case "Monday":
System.out.println("Start of the week!");
break;
case "Tuesday":
System.out.println("Regular workday.");
break;
case "Wednesday":
System.out.println("Midweek.");
break;
case "Thursday":
System.out.println("Almost there.");
break;
case "Friday":
System.out.println("Weekend is coming!");
break;
default:
System.out.println("Weekend!");
}
}
}
How Java Executes This:
- Computes
hashCode()
ofday
(“Friday”). - Uses a precomputed lookup table to jump directly to the
"Friday"
case. - Executes that case without checking previous cases.
✅ Benefit: switch
finds the correct case instantly, instead of checking conditions sequentially.
3. Performance Comparison: if-else
vs switch
Let’s benchmark if-else
and switch
to see which one is faster.
Benchmark Code
public class PerformanceTest {
public static void main(String[] args) {
String testDay = "Friday";
int iterations = 1_000_000;
long start, end;
// Measure time for if-else
start = System.nanoTime();
for (int i = 0; i < iterations; i++) {
ifElseTest(testDay);
}
end = System.nanoTime();
System.out.println("if-else time: " + (end - start) / 1_000_000.0 + " ms");
// Measure time for switch
start = System.nanoTime();
for (int i = 0; i < iterations; i++) {
switchTest(testDay);
}
end = System.nanoTime();
System.out.println("switch time: " + (end - start) / 1_000_000.0 + " ms");
}
static void ifElseTest(String day) {
if (day.equals("Monday")) {}
else if (day.equals("Tuesday")) {}
else if (day.equals("Wednesday")) {}
else if (day.equals("Thursday")) {}
else if (day.equals("Friday")) {}
else {}
}
static void switchTest(String day) {
switch (day) {
case "Monday": break;
case "Tuesday": break;
case "Wednesday": break;
case "Thursday": break;
case "Friday": break;
default: break;
}
}
}
pected Results (Typical Output)
if-else time: 25.3 ms
switch time: 7.8 ms
✅ switch
is ~3 times faster than if-else
because of its lookup mechanism!
4. Why Is switch
Faster?
✅ Switch Uses Hashing (Optimized Lookup)
- Computes
hashCode()
of the string once. - Jumps directly to the case using a lookup table (instead of sequential checks).
❌ If-Else Checks Each Condition One by One
- Needs multiple
.equals()
calls. - Longer chains take more time (e.g., if the matching case is at the bottom).
5. When Should You Use switch
vs. if-else
?
Feature | Use switch | Use if-else |
---|---|---|
Performance | ✅ Faster (optimized lookup) | ❌ Slower (checks sequentially) |
Number of Conditions | ✅ Best for many cases (3+) | ✅ Good for few conditions (1-2) |
Readability | ✅ Easier to read with multiple cases | ❌ Harder to read with many else if |
Complex Conditions | ❌ Only works with exact matches | ✅ Supports complex boolean logic |
✅ Use switch
for many predefined values (like days, commands, menu options).
✅ Use if-else
when conditions are more complex (range checks, combined conditions).
Conclusion
switch
is faster thanif-else
for many cases because it uses hash-based lookups.if-else
checks each condition sequentially, making it slower as the number of cases grows.- For best performance, prefer
switch
when comparing many string values.