TryAssertions.java

package ch01basic;

/**
 * 断言测试
 * java -ea TryAssertions 会检测断言
 * java TryAssertions 默认忽略断言
 */
public class TryAssertions {
    public static void main(String args[]) {
        int daysInMonth = 32;
        if (daysInMonth == 30) {
            System.out.println("Month is April, June, September, or November");

        } else if (daysInMonth == 31) {
            System.out.println(
                    "Month is January, March, May, July, August, October, or December.");

        } else if (daysInMonth == 28 || daysInMonth == 29) {
            System.out.println("Month is February.");

        } else {
            assert false : "daysInMonth has the value " + daysInMonth;
        }
    }
}