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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);

    }

}