Oracle 1Z0-851 問題集

質問 1：
Given:
11.static void test() throws RuntimeException {
12.try {
13.System.out.print("test ");
14.throw new RuntimeException();
15.}
16.catch (Exception ex) { System.out.print("exception "); }
17.}
18.public static void main(String[] args) {
19.try { test(); }
20.catch (RuntimeException ex) { System.out.print("runtime "); }
21.System.out.print("end ");
22.}
What is the result?
A. test exception end
B. test runtime end
C. Compilation fails.
D. test end
E. A Throwable is thrown by main at runtime.
正解：A

質問 2：
Given:
1.public class Boxer1{
2.Integer i;
3.int x;
4.public Boxer1(int y) {
5.x = i+y;
6.System.out.println(x);
7.}
8.public static void main(String[] args) {
9.new Boxer1(new Integer(4));
10.}
11.}
What is the result?
A. A NullPointerException occurs at runtime.
B. A NumberFormatException occurs at runtime.
C. The value "4" is printed at the command line.
D. Compilation fails because of an error in line 9.
E. An IllegalStateException occurs at runtime.
F. Compilation fails because of an error in line 5.
正解：A

質問 3：
Given two files, GrizzlyBear.java and Salmon.java:
1.package animals.mammals;
2.3.
public class GrizzlyBear extends Bear {
4.void hunt() {
5.Salmon s = findSalmon();
6.s.consume();
7.}
8.}
1.package animals.fish;
2.3.
public class Salmon extends Fish {
4.public void consume() { /* do stuff */ }
5.}
If both classes are in the correct directories for their packages, and the Mammal class correctly defines the findSalmon() method, which change allows this code to compile?
A. add import animals.fish.Salmon.*; at line 2 in GrizzlyBear.java
B. add import animals.mammals.GrizzlyBear.*; at line 2 in Salmon.java
C. add import animals.mammals.*; at line 2 in Salmon.java
D. add import animals.fish.*; at line 2 in GrizzlyBear.java
正解：D

質問 4：
Given:
31.class Foo {
32.public int a = 3;
33.public void addFive() { a += 5; System.out.print("f "); }
34.}
35.class Bar extends Foo {
36.public int a = 8;
37.public void addFive() { this.a += 5; System.out.print("b " ); }
38.} Invoked with: Foo f = new Bar(); f.addFive(); System.out.println(f.a);
What is the result?
A. f 8
B. b 13
C. f 3
D. An exception is thrown at runtime.
E. Compilation fails.
F. f 13
G. b 3
H. b 8
正解：G

質問 5：
A developer is creating a class Book, that needs to access class Paper. The Paper class is deployed in a JAR named myLib.jar. Which three, taken independently, will allow the developer to use the Paper class while compiling the Book class? (Choose three.)
A. The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/myLib.jar.
B. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac -classpath /foo/myLib.jar Book.java
C. The JAR file is located at $JAVA_HOME/jre/classes/myLib.jar.
D. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac -cp /foo/myLib.jar/Paper Book.java.
E. The JAR file is located at /foo/myLib.jar and the Book class is compiled using javac -d /foo/myLib.jar Book.java
F. The JAR file is located at /foo/myLib.jar and a classpath environment variable is set that includes /foo/myLib.jar/Paper.class.
G. The JAR file is located at $JAVA_HOME/jre/lib/ext/myLib.jar..
正解：A,B,G

質問 6：
DRAG DROP
Click the Task button.

正解：


質問 7：
Given:
11.class Alpha {
12.public void foo() { System.out.print("Afoo "); }
13.}
14.public class Beta extends Alpha {
15.public void foo() { System.out.print("Bfoo "); }
16.public static void main(String[] args) {
17.Alpha a = new Beta();
18.Beta b = (Beta)a;
19.a.foo();
20.b.foo();
21.}
22.}
What is the result?
A. Bfoo Bfoo
B. Afoo Bfoo
C. An exception is thrown at runtime.
D. Compilation fails.
E. Bfoo Afoo
F. Afoo Afoo
正解：A

質問 8：
Given:
1.public class GC {
2.private Object o;
3.private void doSomethingElse(Object obj) { o = obj; }
4.public void doSomething() {
5.Object o = new Object();
6.doSomethingElse(o);
7.o = new Object();
8.doSomethingElse(null);
9.o = null;
10.}
11.}
When the doSomething method is called, after which line does the Object created in line 5 become available for garbage collection?
A. Line 6
B. Line 10
C. Line 8
D. Line 5
E. Line 7
F. Line 9
正解：C