问题:You want a class to have access to members of another class in the same package. Which is the most restrictive access modifier that will accomplish that will accomplish this objective?()A、 PublicB、 PrivateC、 ProtectedD、 TransientE、 No access modifier is required.
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问题:程序员已经创建了一个类,该类的实例可以用做Hashtable 的键(key)。哪两项是对的?() A、该类有一个返回类型为 int 的 equals 方法。B、该类有一个返回类型为 boolean 的 equals 方法。C、该类有一个接收一个参数的 equals 方法。D、该类有一个接收两个参数的 equals 方法。
问题: 1. class TestA { 2. TestB b; 3. TestA() { 4. b = new TestB(this); 5. } 6. } 7. class TestB { 8. TestA a; 9. TestB(TestA a) { 10. this.a = a; 11. } 12. } 13. class TestAll { 14. public static void main (String args[]) { 15. new TestAll().makeThings(); 16. // ...code continues on 17. } 18. void makeThings() { 19. TestA test = new TestA(); 20. } 21. } Which two statements are true after line 15, before main completes?()A、 Line 15 causes a stack overflow.B、 An exception is thrown at runtime.C、 The object referenced by a is eligible for garbage collection.D、 The object referenced by b is eligible for garbage collection.E、 The object referenced by a is not eligible for garbage collection.F、 The object referenced by b is not eligible for garbage collection.
问题: public class test { public static void add3 (Integer i) int val = i.intValue ( ); val += 3; i = new Integer (val); } public static void main (String args [ ] ) { Integer i = new Integer (0); add3 (i); system.out.printIn (i.intValue ( ) ); } What is the result?() A、 Compilation will fail.B、 The program prints “0”.C、 The program prints “3”.D、 Compilation will succeed but an exception will be thrown at line 3.
问题:Which two can be used to create a new Thread? ()A、 Extend java.lang.Thread and override the run method.B、 Extend java.lang.Runnable and override the start method.C、 Implement java.lang.thread and implement the run method.D、 Implement java.lang.Runnable and implement the run method.E、 Implement java.lang.Thread and implement the start method.
问题:Which two are true about the JSTL core iteration custom tags?()A、It may iterate over arrays, collections, maps, and strings.B、The body of the tag may contain EL code, but not scripting code.C、When looping over collections, a loop status object may be used in the tag body.D、It may iterate over a map, but only the key of the mapping may be used in the tag body.E、When looping over integers (for example begin=’1’ end=’10’), a loop status object may not be used inthe tag body.
问题: 1. interface A { public void aMethod(); } 2. interface B { public void bMethod(); } 3. interface C extends A,B { public void cMethod(); } 4. class D implements B { 5. public void bMethod() { } 6. } 7. class E extends D implements C { 8. public void aMethod() { } 9. public void bMethod() { } 10. public void cMethod() { } 11. } What is the result?() A、 Compilation fails because of an error in line 3.B、 Compilation fails because of an error in line 7.C、 Compilation fails because of an error in line 9.D、 If you define D e = new E(), then e.bMethod() invokes the version of bMethod()defined in Line 5.E、 If you define D e = (D)(new E()),then e.bMethod() invokes the version of bMethod() defined in Line 5.F、 If you define D e = (D)(new E()), then e.bMethod() invokes the version of bMethod() defined in Line 9.
问题: You are assigned the task of building a panel containing a TextArea at the top, a label directly below it,and a button directly below the label. If the three components are added directly to the panel. Which layout manager can the panel use to ensure that the TextArea absorbs all of the free vertical space when the panel is resized?()A、 GridLayout.B、 CardLayout.C、 FlowLayout.D、 BorderLayout.E、 GridBagLayout.
问题: 现有: 1. interface Altitude { 2. //insert code here 3. } 和4个声明: int HIGH = 7; public int HIGH = 7; abstract int HIGH = 7; interface int HIGH = 7; 分别插入到第2行,有多少行可以编译?() A、 0B、 1C、 2D、 3E、 4
问题:类的可访问性不影响类成员的可访问性
问题: A developer is creating a class Book that needs to access class Paper.The Paper class is deployed in a JARnamedmyLib.jar.Whichthree,taken independently,will allow the developer to use the Paper class while compiling the Book class?()A、The JAR fileis located at$JAVA_HOME/jre/classes/myLib.jar.B、The JAR fileis located at$JAVA_HOME/jre/lib/ext/myLib.jar.C、TheJ AR fileis located at/foo/myLib.jar and aclasspath environment variable is set that includes /foo/myLib.jar/Paper.class.D、The JAR fileis located at/foo/myLib.jar and a classpath environment variable is set that includes/foo/myLib.jar.E、The JAR file is located at/foo/myLib.jar and the Book class is compiled using javac-cp/foo/myLib.jar/Paper Book.java.F、The JAR file is located at/foo/myLib.jar and the Book class is compiled using javac-classpath/foo/myLib.jar Book.java.
问题: 10. public class ClassA { 11. public void methodA() { 12. ClassB classB = new ClassB(); 13. classB.getValue(); 14. } 15. } And: 20. class ClassB { 21. public ClassC classC; 22. 23. public String getValue() { 24. return classC.getValue(); 25. } 26. } And: 30. class ClassC { 31. public String value; 32. 33. public String getValue() { 34. value = “ClassB”; 35. return value; 36. } 37. } Given: ClassA a = new ClassA(); a.methodA(); What is the result?()A、 Compilation fails.B、 ClassC is displayed.C、 The code runs with no output.D、 An exception is thrown at runtime.
问题: 11. class Payload { 12. private int weight; 13. public Payload(int wt) { weight = wt; } 13. public void setWeight(mt w) { weight = w; } 15. public String toString { return Integer.toString(weight); } 16. } 17. 18. public class TestPayload { 19. static void changePayload(Payload p) { 20. /* insert code here */ 21. } 22. 23. public static void main(String[] args) { 24. Payload p = new Payload(); 25. p.setWeight(1024); 26. changePayload(p); 27. System.out.println(”The value of p is “+ p); 28. } 29. } Which statement, placed at line 20, causes the code to print “The value of p is 420.”?() A、 p.setWeight(420);B、 p.changePayload(420);C、 p = new Payload(420);D、 Payload.setWeight(420);E、 p = Payload.setWeight(420);F、 p = new Payload(); p.setWeight(420);
问题:移位和按位运算符有哪些作用?()A、 左移“〈〈”可将整数乘以2或者2的若干次方B、 按位与“&”可设置二进制数的某些位为0C、 按位或“”可将两个二进制数相加D、 按位异或“^”可将二进制数的某些位或者所有位设为相反的值E、 无符号右移“>>>”可将整数除以2或者2的若干次方
问题: 现有: class TestApp{ public static void main (String[] args){ int [5] myarray={ 10, 11, 12, 13, 14); int sum=0; for (int x : myarray) sum+=x; System. out. println( "sum= "+sum); } } 上述程序运行后的结果是哪项?() A、 sum=10B、 sum=70C、 sum=60D、 运行时抛出异常
问题:以下关于File对象的描述中,错误的是()A、File对象是不可变的,一旦创建,它所指向的文件就不能改变;B、File对象不一定要指向实际存在的文件或文件夹;C、File类具有强大的文件和文件夹操作能力;D、File对象的功能仅限于关于文本文件;
问题:构造函数只能重载不能覆盖
问题: 现有: class Banana2 f static int X=2; public static void main (String [] args) { int X=2; Banana2 b=new Banana2(); b.go(x); } static {x+=x; } void go (int x) { ++x; System. out.println (x); } 结果为:() A、7B、5C、3D、2
问题: 1. interface DoStuff2 { 2. float getRange(int low, int high); } 3. 4. interface DoMore { 5. float getAvg(int a, int b, int c); } 6. 7. abstract class DoAbstract implements DoStuff2, DoMore { } 8. 9. class DoStuff implements DoStuff2 { 10. public float getRange(int x, int y) { return 3.14f; } } 11. 12. interface DoAll extends DoMore { 13. float getAvg(int a, int b, int c, int d); } What is the result?() A、 The file will compile without error.B、 Compilation fails. Only line 7 contains an error.C、 Compilation fails. Only line 12 contains an error.D、 Compilation fails. Only line 13 contains an error.E、 Compilation fails. Only lines 7 and 12 contain errors.F、 Compilation fails. Only lines 7 and 13 contain errors.G、 Compilation fails. Lines 7, 12, and 13 contain errors.
问题:Java语言中表达式“11”+22的结果是哪项?() A、33B、1122C、22D、表达式错误