public class Resource{

public Worker owner;

}

public class Worker{

private boolean ready=true;

public synchronized boolean isReady(){

return ready;

}

public synchronized vod work(Worker other,Resource resource){

while(ready){

while(resource.owner!=this){

try{

wait(10);

}

catch(InterruptedException e){}

}

if(other.isReady()){

resource.owner=other;

}else{

//do work with resource

ready=false;

resource.owner=other;

}

}

}

}

And given this fragment:

Worker w1=new Worker();

Worker w2=new Worker();

Resource r=new Resource();

resource.owner=w1;

new Thread(()->{w1.work(w2,r);}).start();

new Thread(()->{w2.work(w1,r);}).start();

哪个描述了片段?

public class Thing{

private String name;

public Thing(String name){

this.name=name;

}

public String toString(){

return name;

}

}

and

public class Tester{

public static void main(String[] args){

Thing[] things=processThings();

/* line 1 */

for(Thing t:things){

System.out.println(t);

}

}

public static Thing[] processThings(){

Thing[] things=new Thing[3];

things[0]=new Thing(“Hat”);

things[1]=new Thing(“Rat”);

things[2]=things[0];

things[0]=new Thing(“Cat”);

things[1]=things[2];

return things;

}

}

在第一行有多少Thing对象适合进行垃圾收集?  

abstract class Base{

 abstract protected float getVal();

}

public class Test extends Base{

 public float getVal() { return 0f;}

 public long getVal(){return 2L;}

 public static void main(String[] args) {

 Test test=new Test();

 float f=test.getVal();

 System.out.println(f+test.getVal());

 }

}

输出是什么?

IntStream,range(1,4)

.peek(System.out::print)

.peek(i->{

if(i==3)

 throw new RuntimeException(“Exception thrown”);

});

结果如何?

public Resource(){

System.out.print(“A”);

}

@Override

public void close(){

System.out.print(“B”);

}

public void printResource(){

System.out.print(“C”);

}

}

and

try(Resource r=new Resource()){

r.printResource();

}finally{

System.out.print(“D”);

}

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?

public class Price{

 private final double value;

 public Price(String value){

 this(Double.parseDouble(value));

 }

 public Price(double value){

 this.value=value;

 }

 public Price(){}

 public double getValue(){return value;}

 public static void main(String[] args) {

 Price p1=new Price("1.99");

 Price p2=new Price(2.99);

 Price p3=new Price();

 System.out.println(p1.getValue()+","+p2.getValue()+","+p3.getValue());

 }

}

结果如何?

List<String> states=List.of("NY","CA","WA","NC","CO");

states.forEach(s-> System.out.println(s)); //line 1

哪个语句与第一行等价?

package test.t1;

public class A{

public int x=42;

protected A(){} //line 1

}

and 

package test.t2;

import test.t1.*;

public class B extends A{

 int x=17; //line 2

 public B(){ super(); } //line 3

}

and 

package test;

import test.t1.*;

import test.t2.*;

public class Tester{

public static void main(String[] args){

String eName=”SMITH”;

String empId=”42”;

and these two code fragments

Fragment 1:

Statement stmt=conn.createStatement();

String sql=”INSERT INTO EMP VALUES(‘ ”+eName+” ’,’ ”+empId+” ’)”;

stmt.executeUpdate(sql);

Fragment 2:

String sql=”INSERT INTO EMP VALUES(?,?)”;

PrepareStatement pStmt=conn.prepareStatement(sql);

pStmt.setObject(1,eName,JDBCType.VARCHAR);

pStmt.setObject(2,empId,JDBCType.VARCHAR);

pStmt.executeUpdate();

哪个代码片段是首选的，为什么?

default void action(){

System.out.println(“a action”);

}

}

and 

interface AbilityB{

void action();

}

and

public class Test implements AbilityA,AbilityB{ //line 1

 public void action(){

 System.out.println("ab action");

 }

 public static void main(String[] args){

 AbilityB x=new Test(); //line 2

 x.action();

 }

}

结果如何?

class Tester{

 public static void main(String[] args) {

 String s="hat at store";

 int x=s.indexOf("at");

 s.substring(x+3);

 x=s.indexOf("at");

 System.out.println(s+" "+x);

 }

}

结果如何?

int i=0;

for(;i<10;i++){

System.out.print(++i+” ”);

}

结果如何?

public class Foo{

 private String a(){

 return "Hello world!";

 }

 public String b(){

 return a();

 }

}

public class Bar extends Foo{

 protected String a(){

 return "Bonjour le monde";

 }

}

public class Baz extends Bar{

 public String b(){

 return a();

 }

 public static void main(String[] args) {

 System.out.println(new Foo().b());

 System.out.println(new Bar().b());

 System.out.println(new Baz().b());

 }

}

输出是什么?

8. public class Test{

9. private final int x=1;

10. static final int y;

11. public Test(){

12. System.out.print(x);

13. System.out.print(y);

14. }

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

16. new Test();

17. }

18. }

结果如何?

class Separators{

 public static String separator=”/”; 

 public static String pathSeparator=”:”;

}

To secure this code, you want to make sure that the client code cannot

modify the public static fields

哪个代码可以完成这个任务?

class MyPersistenceData{

String str;

private void methodA(){

System.out.println(“methodA”);

}

}

你想实现MyPersistenceDate类的java.io.Serializable接口，应该重写哪个方法?  

/* line n1 */

 A(){

 super(“The Mandatory Criteria Yet to Meet”);

}

}

15.public class TestCE {

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

17. int a=10,b=13;

18. try{

19. if(a<b){

20. throw new A();

21. }

22. }

23. catch (Exception e){ System.out.println(e); }

24. System.out.println("Continue...");

25. }

26.}

你必须定义异常类A。 如果第19行的cindition为true，并且在第20行抛出一个异常，程序执行必须终止，第n1行的哪个代码片段根据要求定义了A ?  

public class Main{

 public static void main(String[] args){

try{

 Path path=Paths.get(“/u01/work”);

 //line 1

 System.out.println(attributes.isDiractory()); 

}catch(IOException e){

 e.printStackTrace();

}

}

}

you want to examine whether path is a directory

插入到第1行中的哪段代码可以完成这个任务?  

 public default void print(String msg){

System.out.println(“Message from Copier:”+msg);

}

}

and

public abstract class AbstractCopier{

 protected void print(String load){

 System.out.println(“Message from Abstract Copier:”+load);

}

}

and

public class TestImpl extends AbstractCopier implements Copier{

public static void main(String[] args){

TestImpl test=new TestImpl();

test.print(“Attempt00”);

}

}

输出是什么?