一、 选择
1、下面哪些是java语言中的关键字？ A sizeof B abstract C NULL D Native
2、下面语句哪个是正确的？ A char='abc'; B long l=oxfff; C float f=0.23; D double=0.7E-3;
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
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 二、多项选择
1、下面哪些语句能够正确地生成5个空字符串？ A String a[]=new String[5]; for(int i=0;i<5;a[++]=""); B String a[]={"","","","",""}; C String a[5]; D String[5]a;
E String []a=new String[5]; for( int i=0;i<5;a[i++]=null);
2、下面哪些选项将是下述程序的输出？
public class Outer{
public static void main(String args[]){
Outer: for(int i=0; i<3; i++)
inner:for(int j=0;j<3;j++){
if(j>1) break;
System.out.println(j+"and"+i);
}
}
}
A 0 and 0 B 0 and 1 C 0 and 2 D 0 and 3
E 2 and 2
F 2 and 1
G 2 and 0
3、下面哪个语句正确地声明一个整型的二维数组？ A int a[][] = new int[][]; B int a[10][10] = new int[][]; C int a[][] = new int[10][10]; D int [][]a = new int[10][10];
E int []a[] = new int[10][10]; 三、 编程题
1、编写一个程序，用选择法对数组a[]={20,10,50,40,30,70,60,80,90,100}进行从大到小的排序。
以下是答案: | 
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