public interface APIInterface{

public default void process(){

System.out.println("Process() called 1.");

}

}

and

public abstract class AbstractAPI{

public abstract void process();

}

and

public class ApiImpl extends AbstractAPI implements APIInterface{

public void process(){

System.out.println("Process() called 2.");

}

public static void main(String[] args){

var impl=new ApiImpl();

impl.process();

}

}

结果如何?

Locale locale=Locale.US;

//line 1

double currency= 1_00.00;

System.out.println(formatter.format(currency));

您希望将货币的值显示为$100.00。  

插入到第1行中的哪段代码可以完成这个任务?  

int i=10;

do{

for(int j=i/2;j>0;j--){

System.out.print(j+" ");

}

i-=2;

}while(i>0);

结果如何?

class NoMatchException extends RuntimeException{}

public class Test{

public static void main(String[] args){

try{

if("oracle".equals("ORACLE".toLowerCase())){

throw new NoMatchException();

}

}catch(NoMatchException | NullPointerException npe){

System.out.println("Exception 1");

}catch(RuntimeException e){

System.out.println("Exception 2");

}catch(Exception e){

System.out.println("Exception 3");

}finally{

System.out.println("Finally Block");

}

}

}

这个程序打印了多少行文本?  

public void foo(Collection arg){

System.out.println("Bonjour le monde!");

}

}

and

public class Bar extends Foo{

public void foo(List arg){

System.out.println("Hello world!");

}

public static void main(String ... args){

List<String> li=new ArrayList<>();

Collection<String> co=li;

Bar b=new Bar();

b.foo(li);

b.foo(co);

}

}

输出是什么?

public void foo(Collection arg){

System.out.println("Bonjour le monde!");

}

}

and

public class Bar extends Foo{

public void foo(Collection arg){

System.out.println("Hello world!");

}

public static void main(String ... args){

List<String> li=new ArrayList<>();

Bar b=new Bar();

Foo f=b;

b.foo(li);

f.foo(li);

}

}

输出是什么?

public class Calculator{

public static void main(String ... args){

MyInterface myInterface=a->a+1;

System.out.println(MyInterface.add(10));

}

}

interface MyInterface{

int add(int x);

}

哪个接口从java.util.function包可以用户也重构Calculator类?   

public class Location{

static String city;

public Location(String locationCity){

city=locationCity

}

}

and

public class Main{

public static void main(String[] args){

var location=new Location("San Francisco");

location=null;

System.gc();

System.out.println(Location.city);

}

}

结果如何?

public class A{

int a=0;

int b=0;

int c=0;

public void foo(int i){

a+=b*i;

c-=b*i;

}

public void setB(int i){

b=i;

}

}

使类A线程安全?（答案有争议）

1. enum Alphabet{

2. A,B,C;

3.

4. }

Examine this code:

System.out.println(Alphabet.getFirstLetter());

在第3行应该写什么代码来让这个代码输出A?  

class.forName(JDBC_DRIVER_CLASS_NAME.;

什么时候需要执行这条语句?  

1. List<String> fruits =List.of("banana","orange","apple","lemon");

2. fruits.sort(new Comparator<String>(){

@Override

public int compare(String m,String n){

return n.compareTo(m);

}

});

哪个语句将重构第2行以使用lambda表达式?

public static void main(String[] args){

List<Integer> even=List.of();

even.add(0,-1);

even.add(0,-2);

even.add(0,-3);

System.out.println(even);

}

输出是什么?

class FooException extends RuntimeException{}

and

public class Foo{

static void foo(){

bar();

}

static void bar() throws FooException{

throw new FooException();

}

public static void main(String[] args) {

try(Reader r=new StringReader("how now brown cow")){

bar();

System.out.println("A");

}catch (FooException ex){

foo();

System.out.println("B");

}catch (Exception ex){

System.out.println("C");

}finally {

System.out.println("D");

}

}

}

如果有的话，执行Foo print是什么?

public class Option{

 public static void main(String[] args) {

 System.out.println("Ans:"+convert("a").get());

 }

 private static Optional<Integer> convert(String a){

 try{

 return Optional.of(Integer.parseInt(a));

 }catch (Exception e){

 return Optional.empty();

 }

 }

}

结果如何?

int x=0;

while(x<10){

System.out.print(x++);

}

哪个“for”循环产生相同的输出?

package p1;

import java.util.*;

abstract class X {

 protected final List<String> items;

 protected X (List<String> items){

 this. items =items;

 }

 protected abstract void doprocess ();

 public void removeItem(String item){

 items. remove (item);

 }

}

and

package p2;

import p1.X;

import java.util.*;

public class Y extends X {

 public Y ( ){

 super(new ArrayList<String>());

 }

 public void doprocess ( ) {

 items. forEach(System. out::println);

 }

 public void removeItem(String item){

 super. removeItem (item);

 }

}

为什么编译失败?（答案有争议）

5. class A{ }

6. class B extends A{}

7. class C extends B{}

8. public class Test{

9. public static void main(String[] args) {

10. List<? extends A> listA=new ArrayList<>();

11. List<B> listB=new ArrayList<B>();

12. List<? extends B> listC=new ArrayList<>();

13. listA=listB;

14. listC=listB;

15. }

16. }

那个选项是对的?

int one=1;

static int two=2;

static final int three=3;

}

public class ExampleClass implements ExampleInterface{

public static void main(String[] args){

ExampleInterface theInstance =new ExampleClass();

//line 1

}

}

当插入第1行时，哪三个语句会导致编译器错误?  

public void foo(Collection arg){

System.out.println("Bonjour le monde!");

}

}

and

public class Bar extends Foo{

public void foo(Collection arg){

System.out.println("Hello world!");

}

public void foo(List arg){

System.out.println("Ola Mundo!");

}

}

and

Foo f1=new Foo();

Foo f2=new Bar();

Bar b2=new Bar();

Collection<String> c=new ArrayList<>();

哪三个是正确的?