# Java If Condition - Full Guide
The `if` statement is one of the most fundamental control flow statements in Java. It allows your program to execute certain code blocks conditionally. Here's a complete guide to Java's `if` condition.
## Basic If Statement
```java
if (condition) {
// code to execute if condition is true
}
```
Example:
```java
int age = 20;
if (age >= 18) {
System.out.println("You are an adult.");
}
```
## If-Else Statement
```java
if (condition) {
// code if true
} else {
// code if false
}
```
Example:
```java
int score = 75;
if (score >= 50) {
System.out.println("Passed!");
} else {
System.out.println("Failed.");
}
```
## If-Else If-Else Statement
```java
if (condition1) {
// code if condition1 is true
} else if (condition2) {
// code if condition2 is true
} else {
// code if all conditions are false
}
```
Example:
```java
int grade = 85;
if (grade >= 90) {
System.out.println("A");
} else if (grade >= 80) {
System.out.println("B");
} else if (grade >= 70) {
System.out.println("C");
} else {
System.out.println("D or below");
}
```
## Nested If Statements
```java
if (condition1) {
if (condition2) {
// code if both conditions are true
}
}
```
Example:
```java
int age = 25;
boolean hasLicense = true;
if (age >= 18) {
if (hasLicense) {
System.out.println("You can drive!");
} else {
System.out.println("You need a license to drive.");
}
} else {
System.out.println("You're too young to drive.");
}
```
## Conditional Operators
Common operators used in if conditions:
- **Relational operators**: `==`, `!=`, `>`, `<`, `>=`, `<=`
- **Logical operators**: `&&` (AND), `||` (OR), `!` (NOT)
Example:
```java
int temperature = 25;
boolean isSunny = true;
if (temperature > 20 && isSunny) {
System.out.println("Great weather for a picnic!");
}
if (temperature <= 0 || temperature >= 40) {
System.out.println("Extreme weather condition!");
}
```
## Ternary Operator (Shorthand If-Else)
```java
variable = (condition) ? expressionTrue : expressionFalse;
```
Example:
```java
int time = 20;
String result = (time < 18) ? "Good day." : "Good evening.";
System.out.println(result);
```
## Common Mistakes to Avoid
1. Using assignment `=` instead of equality `==`:
```java
if (x = 5) { } // Wrong! This assigns 5 to x
if (x == 5) { } // Correct
```
2. Forgetting curly braces (though optional for single statements):
```java
if (condition)
statement1; // Only this is part of if
statement2; // Always executes
```
3. Overly complex conditions that could be simplified:
```java
// Instead of:
if (x > 5 && x < 10 || x == 15 && !(y < 2))
// Consider breaking into multiple conditions
```
## Best Practices
1. Keep conditions simple and readable
2. Use parentheses to clarify operator precedence
3. Consider using switch statements for multiple fixed values
4. For object comparison, use `.equals()` instead of `==` (unless comparing primitives)
Would you like me to explain any specific aspect of Java's if conditions in more detail?
No comments:
Post a Comment