Difference between & and && in Java?

& is bitwise AND operator comparing bits of each operand.
For example,

int a = 4;
int b = 7;
System.out.println(a & b); // prints 4
//meaning in an 32 bit system
// 00000000 00000000 00000000 00000100
// 00000000 00000000 00000000 00000111
// ===================================
// 00000000 00000000 00000000 00000100

&& is logical AND operator comparing boolean values of operands only. It takes two operands indicating a boolean value and makes a lazy evaluation on them.

& is bitwise. && is logical.

& evaluates both sides of the operation.
&& evaluates the left side of the operation, if it's true, it continues and evaluates the right side.