JAVA基础知识习题.doc

JAVA基础知识习题.一、 选择1、 下面哪些是java语言中的关键字？ A sizeof B abstract C NULL D Native2、 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 STRpublic 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 isThe String No.2 is String 2The String No.3 is a stringThe String No.4 is stringThe String No.5 is a string B The String No.1 isThe String No.2 is String 2The String No.3 is a stringThe String No.4 is tringThe String No.5 is a string C The String No.1 isThe String No.2 is String 2The String No.3 is a stringThe String No.4 is strinThe 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 String5; for(int i=0;i5;a+=);B String a=,;C String a5;D String5a;E String a=new String5; for( int i=0;i5;ai+=null);2、 下面哪些选项将是下述程序的输出？ public class Outerpublic static void main(String args)Outer: for(int i=0; i3; i+)inner:for(int j=0;j1) 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 03、 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 a1010 = new int;C int a = new int1010; D int a = new int1010;E int a = new int1010;三、 编程题编写一个程序，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:一、 选择题答案 选择第1题B选择第2题D选择第3题A选择第4题B二、多项选择题答案多项选择第1题AB多项选择第2题ABC多项选择第3题CDE三、 编程题答案编程题public class ArraySortpublic static void main(String args)int array=20,10,50,40,30,70,60,80,90,100;int i,j,k,t;int l=array.length;for(i=0;iL-1;I+)k=i;for(j=i+1;jL;J+)if(arra