在Java中,以下哪些类定义在java.lang包中。()
A.Frame
B.Object
C.Applet
D.Thread
BD
A.Frame
B.Object
C.Applet
D.Thread
BD
A.抽象类在Java语言中表示的是一种继承关系,一个类只能使用一次继承。但是一个类却可以实现多个接口
B.在抽象类中可以没有抽象方法
C.实现抽象类和接口的类必须实现其中的所有方法,除非它也是抽象类。接口中的方法都不能被实现
D.接口中定义的变量默认是publicstaticfinal型,且必须给其初值,所以实现类中不能重新定义,也不能改变其值
A.程序执行过程中需要的所有类都是通过字节码校验程序装入的
B.代码的运行是由Java运行环境中的解释器完成的
C.在运行时,字节码要经过装入,校验之后,才能在解释器中执行
D.在缺省的安全配置条件下,Java pplet不能访问任何本地资源
A.类体中只能有变量定义和成员方法的定义,不能有其他语句
B.构造函数是类中的特殊方法
C.类一定要声明为public的,才可以执行
D.一个java文件中可以有多个class定义
从供选择的答案中选出应填入下面一段英文中______内的正确答案。
Java was introduced by Sun Microsystems in 1995 and instantly(1)created a new sense of the interactive possibilities ofthe Web. Both ofthe major Web browsers include a Java(2)virtual machine. Almost all major operating system developers (IBM, Microsoft, and others) have added Java(3)compilers as part oftheir product offerings.
The Java virtual machine includes an optional just-in-time compiler that(4)dynamically compiles bytecode into executable code as an alternative to(5)interpreting one bytecode instruction at a time. In many(6)cases, the dynamic JIT compilation is faster than the virtual machine interpretation.
JavaScript should not be(7)confused with Java. JavaScript, which originated at Netscape, is interpreted at a higher level, is easier to learn than Java, but(8)lacks some of the portability of Java and the speed of bytecode. Because Java applets will run on almost any operating system without(8)requiring recompilation and because Java has no operating system-unique extensions or variations, Java is generally regarded as the most strategic(10)language in which to develop applications for the Web.
供选择的答案:
1.confused 2.compilers 3.dynamically 4.requiring 5.cases
6.interpreting 7.language 8.virtual 9.created 10.lacks
A.Scala中的if语句可以带返回值
B.Scala中的返回值不需要写return关键字
C.Scala中的main方法定义在object上
D.Scala中没有for循环