Given a file GrizzlyBear.java: 1. package animals.mammals; 2. 3. public class GrizzlyBear extends Bear { 4. void hunt() { 5. Salmon s = findSalmon(); 6. s.consume(); 7. } 8. } and another file, Salmon.java: 1. package animals.fish; 2. 3. public class Salmon extends Fish { 4. void consume() { /* do stuff */ } 5. } Assume both classes are defined in the correct directories for theft packages, and that the Mammal class correctly defines the findSalmon() method. Which two changes allow this code to compile correctly?()
第1题:
1. public class A { 2. public void doit() { 3. } 4. public String doit() { 5. return “a”; 6. } 7. public double doit(int x) { 8. return 1.0; 9. } 10.} What is the result?()
第2题:
1. class SuperClass { 2. public a geta() { 3. return new a(); 4. } 5. } 6. class SubClass extends SuperClass { 7. public b geta() { 8. return new b(); 9. } 10. } Which is true?()
第3题:
1. public class Exception Test { 2. class TestException extends Exception {} 3. public void runTest() throws TestException {} 4. public void test() /* Point X */ { 5. runTest(); 6. } 7. } At Point X on line 4, which code is necessary to make the code compile?()
第4题:
1. public class A { 2. public void method1() { 3. B b=new B(); 4. b.method2(); 5. // more code here 6. } 7. } 1. public class B { 2. public void method2() { 3.C c=new C(); 4. c.method3(); 5. // more code here 6. } 7. } 1. public class C { 2. public void method3() { 3. // more code here 4. } 5. } Given: 25. try { 26. A a=new A(); 27. a.method1(); 28. } catch (Exception e) { 29. System.out.print(”an error occurred”); 30. } Which two are true if a NullPointerException is thrown on line 3 of class C?()
第5题:
GivenafileGrizzlyBear.java: 1.package animals.mammals; 2. 3.public class GrizzlyBear extends Bear{ 4.voidhunt(){ 5.Salmons=findSalmon(); 6.s.consume(); 7.} 8.} and another file,Salmon.java: 1.packageanimals.fish; 2. 3.public class Salmon extends Fish{ 4.voidconsume(){/*dostuff*/} 5.} Assume both classes are defined in the correct directories for theft packages,and that the Mammal class correctly defines the findSalmon()method.Which two changes allow this code to compile correctly?()
第6题:
Given classes defined in two different files: 1. package util; 2. public class BitUtils { 3. private static void process(byte[] b) { } 4. } 1. package app; 2. public class SomeApp { 3. public static void main(String[] args) { 4. byte[] bytes = new byte[256]; 5. // insert code here 6. } 7. } What is required at line 5 in class SomeApp to use the process method of BitUtils?()
第7题:
ClassOne.java 1. package com.abc.pkg1; 2. public class ClassOne { 3. private char var = ‘a’; 4. char getVar() {return var;} 5. } ClassTest.java 1. package com.abc.pkg2; 2. import com.abc.pkg1.ClassOne; 3. public class ClassTest extends ClassOne { 4. public static void main(String[]args) { 5. char a = new ClassOne().getVar(); 6. char b = new ClassTest().getVar(); 7. } 8. } What is the result?()
第8题:
现有: 1. interface Animal { 2. void eat(); 3. } 4. 5. // insert code here 6. 7. public class HouseCat extends Feline { 8. public void eat() { } 9. } 和五个声明: abstract class Feline implements Animal { } abstract class Feline implements Animal { void eat(); } abstract class Feline implements Animal { public void eat(); } abstract class Feline implements Animal { public void eat() { } } abstract class Feline implements Animal { abstract public void eat(); } 分别插入到第5行,有几个可以通过编译?()
第9题:
No code is necessary.
throws Exception
catch ( Exception e )
throws RuntimeException
catch ( TestException e)
第10题:
Compilation will succeed if a extends b.
Compilation will succeed if b extends a.
Compilation will always fail because of an error in line 7.
Compilation will always fail because of an error in line 8.
第11题:
public void getNum(){}
public void getNum(double d){}
public float getNum() { return 4.0f; }
public double getNum(float d) { return 4.0d; }
第12题:
Class A
Compilation fails.
An exception is thrown at line 2.
An exception is thrown at line 6.
The code executes with no output.
第13题:
1. public class A { 2. void A() { 3. System.out.println(“Class A”); 4. } 5. public static void main(String[] args) { 6. new A(); 7. } 8. } What is the result?()
第14题:
现有2 个文件: 1. package x; 2. public class X { 3. public static void doX() { System.out.print("doX "); } 4. } 和: 1. class Find { 2. public static void main(String [] args) { 3. //insert code here 4. } 5. } 哪两行分别插入到类Find 的第3 行将编译并产生输出“doX”? ()
第15题:
1. package foo; 2. 3. import java.util.Vector; 4. 5. private class MyVector extends Vector { 6. int i = 1; 7. public MyVector() { 8. i = 2; 9. } 10. } 11. 12. public class MyNewVector extends MyVector { 13. public MyNewVector () { 14. i = 4; 15. } 16. public static void main (String args []) { 17. MyVector v = new MyNewVector(); 18. } 19. } The file MyNewVector.java is shown in the exhibit. What is the result?()
第16题:
ClassOne.java: 1. package com.abe.pkg1; 2. public class ClassOne { 3. private char var = ‘a’; 4. char getVar() { return var; } 5. } ClassTest.java: 1. package com.abe.pkg2; 2. import com.abc.pkg1.ClassOne; 3. public class ClassTest extends ClassOne { 4. public static void main(String[] args) { 5. char a = new ClassOne().getVar();6. char b = new ClassTest().getVar(); 7. } 8. } What is the result?()
第17题:
1. class super { 2. public float getNum() {return 3.0f;} 3. } 4. 5. public class Sub extends Super { 6. 7. } Which method, placed at line 6, will cause a compiler error?()
第18题:
Given classes defined in two different files: 1. package util; 2. public class BitUtils { 3. public static void process(byte[]) { /* more code here */ } 4. } 1. package app; 2. public class SomeApp { 3. public static void main(String[] args) { 4. byte[] bytes = new byte[256]; 5. // insert code here 6. } 7. } What is required at line 5 in class SomeApp to use the process method of BitUtils?()
第19题:
Given a class Repetition: 1. package utils; 2. 3. public class Repetition { 4. public static String twice(String s) { return s + s; } 5. } and given another class Demo: 1. // insert code here 2. 3. public class Demo { 4. public static void main(String[] args) { 5. System.out.println(twice(”pizza”)); 6. } 7. } Which code should be inserted at line 1 of Demo.java to compile and run Demo to print“pizzapizza”?()
第20题:
现有: 1. interface Animal { 2. void eat(); 3. } 4. 5. // insert code here 6. 7. public class HouseCat implements Feline { 8. public void eat() { } 9. } 和以下三个接口声明: interface Feline extends Animal { } interface Feline extends Animal { void eat(); } interface Feline extends Animal { void eat() { } } 分别插入到第 5 行,有多少行可以编译?()
第21题:
process(bytes);
BitUtils.process(bytes);
app.BitUtils.process(bytes);
util.BitUtils.process(bytes);
import util.BitUtils. *; process(bytes);
SomeApp cannot use the process method in BitUtils.
第22题:
Line 33 must be called within a try block.
The exception thrown by method1 in class a is not required to be caught.
The method declared on line 31 must be declared to throw a RuntimeException.
On line 5 of class a, the call to method2 of class b does not need to be placed in a try/catch block.
第23题:
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