1z1-809 無料問題集「Oracle Java SE 8 Programmer II」
Given:
public class product {
int id; int price;
public Product (int id, int price) {
this.id = id;
this.price = price;
}
public String toString() { return id + ":" + price; }
}
and the code fragment:
List<Product> products = Arrays.asList(new Product(1, 10),
new Product (2, 30),
new Product (2, 30));
Product p = products.stream().reduce(new Product (4, 0), (p1, p2) -> {
p1.price+=p2.price;
return new Product (p1.id, p1.price);});
products.add(p);
products.stream().parallel()
.reduce((p1, p2) - > p1.price > p2.price ? p1 : p2)
.ifPresent(System.out: :println);
What is the result?
public class product {
int id; int price;
public Product (int id, int price) {
this.id = id;
this.price = price;
}
public String toString() { return id + ":" + price; }
}
and the code fragment:
List<Product> products = Arrays.asList(new Product(1, 10),
new Product (2, 30),
new Product (2, 30));
Product p = products.stream().reduce(new Product (4, 0), (p1, p2) -> {
p1.price+=p2.price;
return new Product (p1.id, p1.price);});
products.add(p);
products.stream().parallel()
.reduce((p1, p2) - > p1.price > p2.price ? p1 : p2)
.ifPresent(System.out: :println);
What is the result?
正解：E
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Given the code fragment:
Stream<Path> files = Files.walk(Paths.get(System.getProperty("user.home"))); files.forEach (fName -> {//line n1 try { Path aPath = fName.toAbsolutePath();//line n2 System.out.println(fName + ":"
+ Files.readAttributes(aPath, Basic.File.Attributes.class).creationTime ());
} catch (IOException ex) {
ex.printStackTrace();
});
What is the result?
Stream<Path> files = Files.walk(Paths.get(System.getProperty("user.home"))); files.forEach (fName -> {//line n1 try { Path aPath = fName.toAbsolutePath();//line n2 System.out.println(fName + ":"
+ Files.readAttributes(aPath, Basic.File.Attributes.class).creationTime ());
} catch (IOException ex) {
ex.printStackTrace();
});
What is the result?
正解：C
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Given the code fragments:
class ThreadRunner implements Runnable {
public void run () { System.out.print ("Runnable") ; }
}
class ThreadCaller implements Callable {
Public String call () throws Exception {return "Callable"; )
}
and
ExecutorService es = Executors.newCachedThreadPool ();
Runnable r1 = new ThreadRunner ();
Callable c1 = new ThreadCaller ();
// line n1
es.shutdown();
Which code fragment can be inserted at line n1 to start r1 and c1 threads?
class ThreadRunner implements Runnable {
public void run () { System.out.print ("Runnable") ; }
}
class ThreadCaller implements Callable {
Public String call () throws Exception {return "Callable"; )
}
and
ExecutorService es = Executors.newCachedThreadPool ();
Runnable r1 = new ThreadRunner ();
Callable c1 = new ThreadCaller ();
// line n1
es.shutdown();
Which code fragment can be inserted at line n1 to start r1 and c1 threads?
正解：B
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Given the code fragments:
class Employee {
Optional<Address> address;
Employee (Optional<Address> address) {
this.address = address;
}
public Optional<Address> getAddress() { return address; }
}
class Address {
String city = "New York";
public String getCity { return city: }
public String toString() {
return city;
}
}
and
Address address = new Address;
Optional<Address> addrs1 = Optional.ofNullable (address);
Employee e1 = new Employee (addrs1);
String eAddress = (addrs1.isPresent()) ? addrs1.get().getCity() : "City Not available"; System.out.println(eAddress); What is the result?
class Employee {
Optional<Address> address;
Employee (Optional<Address> address) {
this.address = address;
}
public Optional<Address> getAddress() { return address; }
}
class Address {
String city = "New York";
public String getCity { return city: }
public String toString() {
return city;
}
}
and
Address address = new Address;
Optional<Address> addrs1 = Optional.ofNullable (address);
Employee e1 = new Employee (addrs1);
String eAddress = (addrs1.isPresent()) ? addrs1.get().getCity() : "City Not available"; System.out.println(eAddress); What is the result?
正解：A
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Given the code fragments:
interface CourseFilter extends Predicate<String> {
public default boolean test (String str) {
return str.contains ("Java");
}
}
and
List<String> strs = Arrays.asList("Java", "Java EE", "Embedded Java");
Predicate<String> cf1 = s - > s.length() > 3;
Predicate cf2 = new CourseFilter() { //line n1
public boolean test (String s) {
return s.startsWith ("Java");
}
};
long c = strs.stream()
.filter(cf1)
.filter(cf2//line n2
.count();
System.out.println(c);
What is the result?
interface CourseFilter extends Predicate<String> {
public default boolean test (String str) {
return str.contains ("Java");
}
}
and
List<String> strs = Arrays.asList("Java", "Java EE", "Embedded Java");
Predicate<String> cf1 = s - > s.length() > 3;
Predicate cf2 = new CourseFilter() { //line n1
public boolean test (String s) {
return s.startsWith ("Java");
}
};
long c = strs.stream()
.filter(cf1)
.filter(cf2//line n2
.count();
System.out.println(c);
What is the result?
正解：C
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Given:
class Student {
String course, name, city;
public Student (String name, String course, String city) {
this.course = course; this.name = name; this.city = city;
}
public String toString() {
return course + ":" + name + ":" + city;
}
public String getCourse() {return course;}
public String getName() {return name;}
public String getCity() {return city;}
and the code fragment:
List<Student> stds = Arrays.asList(
new Student ("Jessy", "Java ME", "Chicago"),
new Student ("Helen", "Java EE", "Houston"),
new Student ("Mark", "Java ME", "Chicago"));
stds.stream()
.collect(Collectors.groupingBy(Student::getCourse))
.forEach(src, res) -> System.out.println(scr));
What is the result?
class Student {
String course, name, city;
public Student (String name, String course, String city) {
this.course = course; this.name = name; this.city = city;
}
public String toString() {
return course + ":" + name + ":" + city;
}
public String getCourse() {return course;}
public String getName() {return name;}
public String getCity() {return city;}
and the code fragment:
List<Student> stds = Arrays.asList(
new Student ("Jessy", "Java ME", "Chicago"),
new Student ("Helen", "Java EE", "Houston"),
new Student ("Mark", "Java ME", "Chicago"));
stds.stream()
.collect(Collectors.groupingBy(Student::getCourse))
.forEach(src, res) -> System.out.println(scr));
What is the result?
正解：D
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