How can primitive data types be compared with each other?

Primitive data types in Java are compared by their values using comparison operators:

• == (equality)
• != (inequality)
• > (greater than)
• < (less than)
• >= (greater than or equal to)
• <= (less than or equal to)

// Comparing integers
int x = 10;
int y = 20;
boolean isEqual = (x == y); // false
boolean isGreater = (x > y); // false

// Comparing floating-point numbers
double a = 3.14;
double b = 3.14;
boolean areEqualDoubles = (a == b); // true (for exact values)

// Comparing characters
char c1 = 'A';
char c2 = 'B';
boolean isCLessThanC2 = (c1 < c2); // true

// Comparing boolean type
boolean flag1 = true;
boolean flag2 = false;
boolean areFlagsEqual = (flag1 == flag2); // false

It is important to remember that when comparing floating-point numbers (float, double), direct comparison using == can be inaccurate due to how numbers are represented in memory. In such cases, to check for approximate equality, the comparison of the absolute difference with a small epsilon value is used.

double val1 = 0.1 + 0.2; // actually not exactly 0.3 due to precision
double val2 = 0.3;
double epsilon = 1e-9; // Small tolerance

// Inaccurate method
boolean incorrectEquality = (val1 == val2); // may be false

// Recommended method for comparing floating-point numbers
boolean correctEquality = (Math.abs(val1 - val2) < epsilon); // true