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一.选择题:
1.CD
解析:A public是关键字. B 第一个不能是数字
2.C
解析:j=i++ <=> j=i; i++
3.A
解析:float数据需要在尾部加f,且f不能省略
4.AB
解析:C 字符串必须是双引号 D数据类型错误
5.AB
解析:A的赋值运算是最低的14级,B的题目符号错误符号,应该是 ?: ,位于13级
二.简答题
1.bool byte->short->char->int->long->float->double
2. j=i++ <=> j=i; i++; j=++i <=> i++; j=i;
3.||是逻辑或运算符,是两个bool值的或运算;,结果是bool型 . |是位运算,是两个数据的按二进制展开后每位进行或运算,结果是一个数
4.byte->short->char->int->long->float->double
三.编码题
1.
import java.util.Scanner;public class Circle { public static void main(String[] args) { float radius=0.0f ; float circumference=0.0f; float area=0.0f; Scanner input = new Scanner(System.in); Result result = new Result(); System.out.println("请输入圆的半径:"); radius=input.nextFloat(); circumference=result.circumference(radius); area=result.area(radius); System.out.printf("该圆的半径为: R=%2.1f\n",radius); System.out.printf("该圆的周长为: C=2*3.14*%2.1f=%2.1f\n",radius,circumference); System.out.printf("该圆的面积为: S=3.14*%2.1f*%2.1f=%3.3f\n",radius,radius,area); }}class Result{ final float PI=3.14f; public float circumference(float radius){ return 2*PI*radius; } public float area(float radius){ return PI*radius*radius; }} 2.
import java.util.Currency;public class InterestRate { public static void main(String[] args) { int principal = 10000; FinalValue finalValue = new FinalValue() ; System.out.printf("本金:%d\n",principal); System.out.printf("活期一年本金总计:%d\n",(int)finalValue.CurrentDeposit_12(principal)); System.out.printf("定期一年本金总计:%d\n",(int)finalValue.FixedDeposit_12(principal)); System.out.printf("活期两年本金总计:%d\n",(int)finalValue.CurrentDeposit_24(principal)); System.out.printf("定期两年本金总计:%d\n",(int)finalValue.FixedDeposit_24(principal)); }}class FinalValue{ float currentDeposit=0.35f; float fixedDeposit_3=1.10f; float fixedDeposit_6=1.30f; float fixedDeposit_12=1.50f; float fixedDeposit_24=2.10f; float CurrentDeposit_12(int principal){ return principal*currentDeposit/100f+principal; } float CurrentDeposit_24(float principal){ return principal*currentDeposit*2/100f+principal; } float FixedDeposit_12(float principal){ return principal*fixedDeposit_12/100f+principal; } float FixedDeposit_24(float principal){ return 2*principal*fixedDeposit_24/100f+principal; }} 3.
import java.util.Scanner;public class EnCode { public static void main(String[] args) { int plaintext = 0; int ciphertext = 0; int temp=1000; int num=0; int bit[] = new int[4]; Scanner input = new Scanner(System.in); System.out.print("请输入4位正整数:"); plaintext = input.nextInt(); for(int i=0; temp>=1;temp=temp/10,i++){ bit[i]=(int)plaintext/temp; num= bit[i]; System.out.printf("\tbit["+i+"]="+bit[i]); bit[i]=(bit[i]+5)%10; System.out.printf("\tbit["+i+"]="+bit[i]); plaintext=plaintext-num*temp; System.out.println(); } for(int i=0;i<2;i++){ temp=bit[i]; bit[i]=bit[bit.length-1-i]; bit[bit.length-1-i]=temp; } System.out.print("\n密文:"); temp=1000; for(int i=0; temp>=1;temp=temp/10,i++) { ciphertext=bit[i]*temp+ciphertext; } System.out.println(ciphertext); }}