Oracle 1z0-809 問題集

質問 1：
Given:

and the code fragment:

What is the result?
A. 1500.0
B. 2000.0
C. A compilation error occurs.
D. 0.0
正解：A

質問 2：
Given the code fragment:

Which code fragment, when inserted at line 7, enables printing 100?
A. ToIntFunction funRef = e -> e + 10;int result = funRef.apply (value);
B. IntFunction funRef = e -> e + 10;Integer result = funRef.apply (10);
C. ToIntFunction<Integer> funRef = e -> e + 10;int result = funRef.applyAsInt (value);
D. Function<Integer> funRef = e -> e + 10;Integer result = funRef.apply(value);
正解：D

質問 3：
Given the code fragment:

What is the result?
A. Javacourse
B. A compilation error occurs at line n2.
C. A compilation error occurs at line n1.
D. courseJava
正解：C

質問 4：
Given the code fragment:
Map<Integer, String> books = new TreeMap<>();
books.put (1007, "A");
books.put (1002, "C");
books.put (1003, "B");
books.put (1003, "B");
System.out.println (books);
What is the result?
A. {1007=A, 1003=B, 1003=B, 1002=C}
B. {1007=A, 1003=B, 1002=C}
C. {1002=C, 1003=B, 1007=A}
D. {1007=A, 1002=C, 1003=B, 1003=B}
正解：C

質問 5：
Given the code fragment:

What is the result?
A. [X][X, X][X, X, X][X, X, X, X]
B. [X, X]
C. [X][X, X][X, X, X]
D. [X, X][X, X, X, X]
正解：A

質問 6：
Given the code fragment:

Which code fragment, when inserted at line n1, ensures false is printed?
A. boolean b = cs.stream() .findFirst() .get() .equals("Java");
B. boolean b = cs.stream() .anyMatch (w -> w.equals ("Java"));
C. boolean b = cs.stream() .findAny() .get() .equals("Java");
D. boolean b = cs.stream() .allMatch(w -> w.equals("Java"));
正解：B

質問 7：
Given:
final class Folder {//line n1
//line n2
public void open () {
System.out.print("Open");
}
}
public class Test {
public static void main (String [] args) throws Exception {
try (Folder f = new Folder()) {
f.open();
}
}
}
Which two modifications enable the code to print Open Close? (Choose two.)
A. At line n2, insert:final void close () {System.out.print("Close");}
B. Replace line n1 with:class Folder implements AutoCloseable {
C. At line n2, insert:public void close () throws IOException {System.out.print("Close");}
D. Replace line n1 with:class Folder extends Closeable {
E. Replace line n1 with:class Folder extends Exception {
正解：B,C

質問 8：
Given:
class CheckClass {
public static int checkValue (String s1, String s2) {
return s1 length() - s2.length();
}
}
and the code fragment:
String[] strArray = new String [] {"Tiger", "Rat", "Cat", "Lion"}
//line n1
for (String s : strArray) {
System.out.print (s + " ");
}
Which code fragment should be inserted at line n1 to enable the code to print Rat Cat Lion Tiger?
A. Arrays.sort(strArray, (CheckClass : : new) : : checkValue);
B. Arrays.sort(strArray, CheckClass : : new : : checkValue);
C. Arrays.sort(strArray, (CheckClass : : new).checkValue);
D. Arrays.sort(strArray, CheckClass : : checkValue);
正解：D

質問 9：
Given the code fragments:
class MyThread implements Runnable {
private static AtomicInteger count = new AtomicInteger (0);
public void run () {
int x = count.incrementAndGet();
System.out.print (x+" ");
}
}
and
Thread thread1 = new Thread(new MyThread());
Thread thread2 = new Thread(new MyThread());
Thread thread3 = new Thread(new MyThread());
Thread [] ta = {thread1, thread2, thread3};
for (int x= 0; x < 3; x++) {
ta[x].start();
}
Which statement is true?
A. The program prints 1 2 3 and the order is unpredictable.
B. The program prints 1 1 1.
C. The program prints 1 2 3.
D. A compilation error occurs.
正解：A