🕐Day 11 Java learning :

Great! Here's a clean, focused Day 11 Java learning note for you — about Data Type Conversion. I’ll cover:

✅ What it is
❓ Why we need it
🕐 When we use it
🔧 How to use it
🔄 All conversion paths (byte → short → int → long → float → double, etc.)

You can directly use this for your daily log or even turn it into a blog/PDF later!

📘 Day 11 — Java Data Type Conversion

🔹 What is Data Type Conversion in Java?

Data Type Conversion means converting one data type into another.

Java supports:

✅ Widening Conversion → done automatically
✅ Narrowing Conversion → needs manual casting

❓ Why Do We Need It?

To store values in compatible types
To perform operations between different data types
To avoid errors during assignment or calculations
To support method overloading, user input, etc.

🕐 When Do We Use It?

During mathematical operations
While assigning variables of different types
When reading input (like from Scanner)
In functions/methods that require specific types

🔧 How to Use It?

1. Widening Conversion (Automatic)

No cast needed — Java does it for you.

byte b = 10;
short s = b;   // byte → short
int i = s;     // short → int
long l = i;    // int → long
float f = l;   // long → float
double d = f;  // float → double

System.out.println(d);  // Output: 10.0

2. Narrowing Conversion (Manual)

You must cast manually. Risk of data loss.

double d = 99.99;
float f = (float) d;
long l = (long) f;
int i = (int) l;
short s = (short) i;
byte b = (byte) s;

System.out.println(b);  // Output: May lose precision

🔄 Full Widening Conversion Chart

From	To
byte	short, int, long, float, double
short	int, long, float, double
int	long, float, double
long	float, double
float	double
char	int, long, float, double

✅ All above conversions are automatic (widening).

🔄 Full Narrowing Conversion Chart

From	To	Needs Casting?
double	float, long, int, short, byte	✅ Yes
float	long, int, short, byte	✅ Yes
long	int, short, byte	✅ Yes
int	short, byte	✅ Yes
short	byte	✅ Yes
int	char	✅ Yes