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对于一个类，要获取它的一个实例，通常的做法是提供一个公用的构造函数，然而还有另一种方法，我们称之为静态工厂方法，实质上也就是一个简单的静态方法，它返回一个类的实例。其实，静态工厂方法获取对象实例，我们并不陌生，我们来看看API中的一个实例：java.lang.Boolean类：public static Boolean valueOf(boolean b){       return

685. For an object to be a target for a Thread, that object must be of type:Fill in the blank.正确答案: Runnable 686. If you supply a target object when you create a new Thread, as in:Thread t=n

600. Your chief Software designer has shown you a sketch of the new Computer parts system she is about to create. At the top of the hierarchy is a Class called Computer and under this are two child cl

 void test(){if (!Test.this.flag);{sample();}}private boolean flag = false;}publi void sample(){System.out.println("Sample");}public Test(){(new Inner()).test();}public sta

10.What output is produced by the following program?class Test{public static void main(String args[]){long size=10;int[] array=new int[size];size=20;System.out.println(array.length);}}

615. Given the following class definition:public class Droitwich{class one {private class two{public void main(){System.out.println("two");}}}}Which of the following statements are

930. What String instance method would return true when invoked like this?a.method(b);Where a="GROUNDhog" and b="groundHOG"?Select the one right answer.A. equals()B. toLowerCase()C. toUppe

 B. float f=-412;C. int other=(int)true;D. double d=0x12345678;E. short s=10;正确答案: A、B、D、E 444. What is the result of executing the following code:class Test{public static void main(

 int index;Test(int mpg){milesperGallon=mpg;index=0;}Test(){}public static void main(String[] args){int index;Test c=new Test(25);if(args.length>0)if(args[index].equals("Hiway"))

1. What will happen when you compile and run this program: class Test{pubilc static void main(String[]args){int length=100;int[] d=new int[length];for(int index=0;indexSystem.out.println(d[index]);}}S

564. What will appear in the standard output when you run the Tester class?class Tester{int var;Tester(int var){this ("hello");}Tester(String s){this();System.out.println(s);}Teste

1．             Wich three are valid declarations of a char?(choose three)A   char c1=064770;B   char c2=’face’;C   char c3=0Xbeef;D   char c4=/u0022;E   char c5=’/iface’;F   char c6=’/ufac

22. A Java array is an ordered collection of three kinds of things. What are they?Fill in the blank.正确答案：primitives. object references, references to other arrays.  20. There are seven chara

880. If you run the following code on a on a PC from line directory c:/ source:import java.io.*;class Test {public static void main(String[] args) throws Exception{File file = new File("Ran.te

Section（部分，节）：Language Fundamentals（基本原则）Problem[1]A method is ...[Select One][1]an implementation of an abstraction.[2]an attribute defining the property ofa particular abstraction[3]a

子类的构造函数会自动调用父类无参数的构造函数 在重写中，所谓子类中方法的访问控制不能比父类中方法的访问控制范围窄是指:Ø       一个package方法可以被重写为package、protected和public的Ø       一个protected方法可以被重写为protected和public的Ø       一个public方法只可以被重写为public的局部变

hashcode是个啥?它与equals的关系? 1.hashcode 拆开看hash可以理解为一种hash算法,经过算法后会得出一个值就叫code,于是得到了我们的hashcode.但是经过计算得到的hashcode不一定是唯一的,比如8/3,7/3结果都是2,这时候我们的对象拥有了相同的hashcode,可以理解为他们被放进了"2" 这个箩里面 2.equals equals是进一步对对象的比

值类型是存储在内存中的堆栈（以后简称栈），而引用类型的变量在栈中仅仅是存储引用类型变量的地址，而其本身则存储在堆中。==操作比较的是两个变量的值是否相等，对于引用型变量表示的是两个变量在堆中存储的地址是否相同，即栈中的内容是否相同。equals操作表示的两个变量是否是对同一个对象的引用，即堆中的内容是否相同。==比较的是2个对象的地址，而equals比较的是2个对象的内容。显然，当equals为t

564. What will appear in the standard output when you run the Tester class?class Tester{int var;Tester(double var){This.var=(int)var;}Tester(int var){this ("hello");}Tester(String s)