3、以下程序测试String 类的各种构造方法,试选出其运行效果。 class STR{ public static void main(String args[]){ String s1=new String(). String s2=new String("String 2"). char chars[]={ a , , s , t , r , i , n , g }. String s3=new String(chars). String s4=new String(chars,2,6). byte bytes[]={0,1,2,3,4,5,6,7,8,9}. StringBuffer sb=new StringBuffer(s3). String s5=new String(sb). System.out.println("The String No.1 is " s1). System.out.println("The String No.2 is " s2). System.out.println("The String No.3 is " s3). System.out.println("The String No.4 is " s4). System.out.println("The String No.5 is " s5). } }
A The String No.1 is The String No.2 is String 2 The String No.3 is a string The String No.4 is string The String No.5 is a string
B The String No.1 is The String No.2 is String 2 The String No.3 is a string The String No.4 is tring The String No.5 is a string
C The String No.1 is The String No.2 is String 2 The String No.3 is a string The String No.4 is strin The String No.5 is a string
D 以上都不对 答:A
4、下面语句段的输出结果是什么? int i = 9. switch (i) { default: System.out.println("default"). case 0: System.out.println("zero"). break. case 1: System.out.println("one"). case 2: System.out.println("two"). }
A default
B default, zero
C error default clause not defined
D no output displayed 答:B
二、不定项选择题(在每小题的五个备选答案中选出正确答案,并将正确答案的序号填入题干后面的括号内,错选多选,漏选均不得分。) 1、给出如下代码: class Test{ private int m. public static void fun() { // some code... } } 如何使成员变量m 被函数fun()直接访问? A、将private int m 改为protected int m B、将private int m 改为 public int m C、将private int m 改为 static int m D、将private int m 改为 int m 答: C
2、下面哪几个函数是public void example(){...}的重载函数? A、 public void example( int m){...} B、public int example(){...} C、public void example2(){...} D、 public int example ( int m, float f){...} 答: A,D
3、给出下面的代码段: public class Base{ int w, x, y ,z. public Base(int a,int b) { x=a. y=b. } public Base(int a, int b, int c, int d) { // assignment x=a, y=b w=d. z=c. } } 在代码说明// assignment x=a, y=b处写入如下哪几个代码是正确的? A、 Base(a,b). B、x=a, y=b. C、x=a. y=b.