1Z1-804 全真模擬試験 DEMO

問題2: Given: javac Test.java java ea Test
And the commands:
What is the result?
A.Compilation fails
B.Standard Edition Enterprise Edition Micro Edition
C.Standard Edition class java.lang.AssertionError Micro Edition
D.Standard Edition is printed and an Assertion Error is thrown
正解: D
Explanation:
javac Test.java
will compile the program.
As for command line:
java ea Test
First the code will produce the output:
Standard Edition
See Note below.
The ea option will enable assertions. This will make the following line in the switch statement to be
run:
default: assert false;
This will throw an assertion error. This error will be caught. An the class of the assertion error
(class java.lang.AssertionError) will be printed by the following line:
System.out.println(e.getClass());
Note:The java tool launches a Java application. It does this by starting a Java runtime
environment, loading a specified class, and invoking that class's main method. The method
declaration must look like the following:
public static void main(String args[])
Paramater ea:
-enableassertions[:<package name>"..." | :<class name> ] -ea[:<package name>"..." | :<class
name> ]
Enable assertions. Assertions are disabled by default. With no arguments, enableassertions or -ea
enables assertions.
Note 2:
An assertion is a statement in the JavaTM programming language that enables you to test your
assumptions about your program. Each assertion contains a boolean expression that you believe will
be true when the assertion
executes. If it is not true, the system will throw an error.
public class AssertionError extends Error
Thrown to indicate that an assertion has failed.
Note 3:
The javac command compiles Java source code into Java bytecodes. You then use the Java
interpreter - the
java command - to interprete the Java bytecodes.
Reference:java - the Java application launcher
Reference:java.langClass AssertionError