What is Java "assert" statement?

The assert keyword is used in assert statement which is introduced in Java 1.4.

It helps the code developers to test assumptions and to assert if the outcome is as expected that enables detecting bug and fixing it.

public class AssertExample {

	public static void main(String[] args) {
		assert 0 > 1;
		System.out
				.println("This line is printed since -ea or -enableassertions is not enabled as VM argument.");

	}
}

Format:

assert condition;
assert boolean_expression : string_expression;

assert <condition>: "Error message to display when condition failed";

When this statement is executed:

• If boolean_expression evaluates to true, the statement will pass normally.
• If boolean_expression evaluates to false, the statement will fail with an "AssertionError"

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