题目内容

13.假设A类有如下定义,设a是A类的一个实例,下列语句调用哪个是错误的?()class A { int i; static String s;void method1() { }static void method2() { }}

A. System.out.println(a.i);
B. a.method1();
C. A.method1();
D. A.method2();

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运行以下程序会抛出哪种异常?()publicclassTest{public static void main(String[] args) Object o = null;System.out.println(o);}

ArithmeticException
B. ArrayIndexOutOfBoundsException
C. StringIndexOutOfBoundsException
D. no Exception
E. NullPointerException

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执行如下程序后b的值为? ()int x, b=0; for(x = 0; x <= 5; ++x){ if (x == 2) continue; ++b; }

A. 5
B. 4
C. 3

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给定如下代码:3. class Alpha {4. static String s = " ";5. protected Alpha() { s += "alpha "; }6. }7. class SubAlpha extends Alpha {8. private SubAlpha() { s += "sub "; }9. }10. public class SubSubAlpha extends Alpha {11. private SubSubAlpha() { s += "subsub "; }12. public static void main(String[] args) {13. new SubSubAlpha();14. System.out.println(s);15. }16. }运行结果为?()

A. subsub
B. sub subsub
C. alpha subsub
D. alpha sub subsub

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运行类C的输出结果为?()class A { public A() { System.out.println( "The default constructor of A is invoked"); }} class B extends A { public B() { System.out.println( "The default constructor of B is invoked"); }} public class C { public static void main(String[] args) { B b = new B(); }}

A. 无任何显示
B. "The default constructor of B is invoked"
C. "The default constructor of A is invoked""The default constructor of B is invoked"
D. "The default constructor of B is invoked""The default constructor of A is invoked"

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13.假设A类有如下定义,设a是A类的一个实例,下列语句调用哪个是错误的?()class A { int i; static String s;void method1() { }static void method2() { }}

A. System.out.println(a.i); B. a.method1(); C. A.method1(); D. A.method2();

运行以下程序会抛出哪种异常?()publicclassTest{public static void main(String[] args) Object o = null;System.out.println(o);}

执行如下程序后b的值为? ()int x, b=0; for(x = 0; x <= 5; ++x){ if (x == 2) continue; ++b; }

运行类C的输出结果为?()class A { public A() { System.out.println( "The default constructor of A is invoked"); }} class B extends A { public B() { System.out.println( "The default constructor of B is invoked"); }} public class C { public static void main(String[] args) { B b = new B(); }}

A. System.out.println(a.i);
B. a.method1();
C. A.method1();
D. A.method2();