public class Main { public static void main(String[] args) { // Enable assertions ClassLoader loader = ClassLoader.getSystemClassLoader(); loader.setDefaultAssertionStatus(true); // Run the assert example AssertExample example = new AssertExample(); example.run(); } } class AssertExample { public void run() { int a = 12; try { assert a == 12; // Assertion without a fail message assert a == 12 : "a is not 12"; assert a == 15 : "a is not 15"; } catch (AssertionError e) { System.out.println(e.getMessage()); } } }