举一反三
- 对于一下程序,其运行结果为 class Base{ public Base(){ System.out.print("C"); } } class Base2 extends Base{ public Base2(){ System.out.print("B"); } } public class TestDemo extends Base2{ int m=1; public TestDemo(){ System.out.println("A"); } public static void main(String args[]){ TestDemo t = new TestDemo(); } }
- 如何能使程序调用Base类的构造方法输出"base constructor"; class Base{ Base(int i){ System.out.println("base constructor"); } Base(){ } } public class Sup extends Base{ public static void main(String argv[]){ Sup s= new Sup(); //One } Sup() { //Two } public void derived() { //Three } }
- 当你编译运行下列程序代码,会得到什么结果? 。 private class Base{ Base(){ int i = 100; System.out.println(i); } } public class Pri extends Base{ static int i = 200; public static void main(String argv[]){ Pri p = new Pri(); System.out.println(i); } }
- 以下代码调试结果 class Base {} class Sub extends Base {} public class CEx{ public static void main(String argv[]){ Base b = new Base(); Sub s = (Sub) b; } }
- 以下程序的编译和运行结果为? abstract class Base{ abstract public void myfunc(); public void another(){ System.out.println("Another method"); } } public class Abs extends Base{ public static void main(String argv[]){ Abs a = new Abs(); a.amethod(); } public void myfunc(){ System.out.println("My Func"); } public void amethod(){ myfunc(); } }
内容
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(6-2)以下代码会出现编译错误。 class Base{ public Base () { System.out.println("1"); } public void Base () { System.out.println("2"); } }
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中国大学MOOC: 下列代码中构造方法的返回类型是()public class Village { Village () { System .out .println(“hiding in Village”) ; } public static void main( String args [ ]) { Village c =new Village ( ) ;}class Village { public static void main( String args [ ]) { Village c =new Village ( ) ; } Village () { System .out .println(“hiding in Village”) ; } }
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(8-1)根据提示补全程序空白处,使程序能够正确运行。 1. 定义类Base package cn.edu.jsu; public class Base { ① void show() { System.out.println("你好,中国!"); } } 2. 定义测试类Demo package per.cn.edu.jsu; import cn.edu.jsu.Base; public class Demo { public static void main(String[] args) { Base.show(); } }
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给出以下代码,请问插入以下哪些语句可以使程序编译通过?( )class Base{public Base(int i){}}public class Example extend Base{public static void main (String arg[]){Example e = new Example(10);}Example(int i){Super(i);}Exanple(String s, int i){this(i);//插入代码处}}请选择一个正确答案: A: Example d = new Example(); B: Super(); C: This(“Hello”,10); D: Base b = ne Base(10);
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以下代码能否通过编译,如果通过编译,运行“java Sub”时得到什么打印结果? abstract class Base{ abstract public void method1();abstract public void method2();}public class Sub extends Base{public static void main(String args[]){Base a = new Sub();a.method1();} public void method1(){System.out.println("method1");}} A: 运行时打印“method1”。 B: 编译时出错:Sub类必须为抽象类。 C: 运行时出错:Sub类不能被实例化。 D: 编译时出错:main()方法中的变量a必须声明为Sub类型。