In Java, an expression is a combination of values, variables, and operators that evaluates to a single value.
Expressions are used to perform calculations or to evaluate a condition.

There are different types of expressions in Java, including:

Arithmetic Expressions

Arithmetic expressions are used to perform mathematical calculations. Some examples of arithmetic expressions include:

int x = 5;
int y = 10;
int z = x + y;
int a = x * y;
double b = y / x;

In this example, we create two integer variables x and y, and use arithmetic expressions to perform calculations and assign the results to z, a, and b. The first expression calculates the sum of x and y, the second expression calculates the product of x and y, and the third expression calculates the quotient of y divided by x.

Relational Expressions

Relational expressions are used to compare values and return a boolean result. Some examples of relational expressions include:

int x = 5;
int y = 10;
boolean isEqual = x == y;
boolean isGreaterThan = x > y;
boolean isLessThanOrEqual = x <= y;

In this example, we use relational expressions to compare the values of x and y and assign the results to boolean variables. The first expression checks whether x is equal to y, the second expression checks whether x is greater than y, and the third expression checks whether x is less than or equal to y.

Logical Expressions

Logical expressions are used to combine boolean values and return a boolean result. Some examples of logical expressions include:

boolean x = true;
boolean y = false;
boolean andResult = x && y;
boolean orResult = x || y;
boolean notResult = !x;

In this example, we use logical expressions to combine boolean values and assign the results to boolean variables. The first expression uses the logical AND operator && to check whether both x and y are true, the second expression uses the logical OR operator || to check whether at least one of x and y is true, and the third expression uses the logical NOT operator ! to invert the value of x.

Conditional Expressions

Conditional expressions, also known as ternary expressions, are used to make a decision based on a condition. They have the following syntax:

condition ? value1 : value2

If the condition is true, the expression evaluates to value1. Otherwise, it evaluates to value2. Here's an example:

int x = 5;
int y = 10;
int max = x > y ? x : y;

In this example, we use a conditional expression to assign the maximum value of x and y to the variable max. If x is greater than y, the expression evaluates to x, otherwise it evaluates to y.