Java基础面试题总结-编程题总结

 

 1.理发题（10份）

（1）110元，洗剪吹31元，可以多少次洗剪吹？最后还剩多少？

（2）一次剪头发15元和一次洗头20元，平均每次消费多少钱？

public class Test04 {
    public static void main(String[]args){
        double money=110;
        double costone=31;
        int count=(int)(money/costone);
        System.out.println("可以理发"+count+"次");
        double lastmoney=money%costone;
        System.out.println("剩余"+lastmoney+"元");
        double avgmoney=(15d+20d)/2d;
        System.out.println("理发15,洗头20,那么平均消费是:"+avgmoney);

2.打印九九乘法表（15分）

public class NineNine {
    public static void main(String[] args) {
        for (int i= 1; i <=9 ; i++) {
          for (int j =1; j <=i ; j++) {
              System.out.print(j+"*"+i+"="+i*j+" ");
            }
            System.out.println();
        }
    }
}

3.编写万用表程序

1 电压挡

2 电流挡

3 电阻档

4 其他档位

5 退出

注意：使用scanner（system.in）时，使用完毕后，一定要关闭扫描器，因为system.in属于IO流，一旦打开，它一直在占用资源，因此使用完毕后切记要关闭。（15分）

public class MulTimter {
    public static void main(String[] args) {
        System.out.println("欢迎使用万用表：");
        Scanner scanner = new Scanner(System.in);
        System.out.println("请选择档位：1电压档  2电流档3电阻档  4其他档位  5退出  ");
        System.out.println("请输入你的选择:");
        String input = scanner.next();
// 过滤无效的选择
        while (!input.equals("1") && !input.equals("2")&& !input.equals("3")
                && !input.equals("4") && !input.equals("5")) {
            System.out.println("请输入有效的选择：");
            input = scanner.next();// 获取用户输入的选择
        }
        // 判断选择
        switch (input) {
            case "1":
                System.out.println("你选择了电压档");
                break;
            case "2":
                System.out.println("你选择了电流档");
                break;
            case "3":
                System.out.println("你选择了电阻档");
                break;
            case "4":
                System.out.println("你选择了其他档");
                break;
            case "5":
                System.out.println("谢谢您的使用！");
                break;
        }
        scanner.close();
    }
}

4.编写三个方法，分别得出一个数组的最大值，最小值，平均值。（15分）

  public class array {
    public static void main(String[] args) {
        int[]array={1,2,3,4,5,6};
        int max=numMax(array);
        System.out.println("最大的数是：" + max);
        int min=numMin(array);
        System.out.println("最小的数是：" + min);
        double avg =numAvg(array);
        System.out.println("平均数是：" +avg);
    }

    private static double numAvg(int[] array) {
        double sum=0;
        double numAvg=0;
        for (int i = 0; i <array.length ; i++) {
           sum+=array[i];
        }
        numAvg=sum/array.length;
        return numAvg;
    }

    private static int numMin(int[] array) {
        int numMin=array[0]; //定义一个最小值
        for (int i = 0; i <array.length ; i++) {
           if (numMin>array[i]){
               numMin=array[i];
           }
        }
        return numMin;
    }

    private static int numMax(int[] array) {
        int numMax=0;
        for (int i = 0; i <array.length ; i++) {
            if (numMax<array[i]){
                numMax=array[i];
            }
        }
        return numMax;
    }
}

5.创建宠物类（属性：名字 ，体重 方法： 奔跑，捕食）在DEMO类实例化宠物，设置名字，调用奔跑，捕食方法（15分）

public class Pet {
    private String name;
    private double weight;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getWeight() {
        return weight;
    }

    public void setWeight(double weight) {
        this.weight = weight;
    }

    void run(){
        System.out.println("它在奔跑");
    }
    void catchFood(){
        System.out.println("它在捕食");
    }
}
class demo{
    public static void main(String[] args) {
        Pet pet = new Pet();
        pet.setName("麒麟");
        pet.setWeight(100);
        System.out.println("我的宠物：" + pet.getName()+"，体重：" + pet.getWeight()+"kg");
        pet.run();
        pet.catchFood();
    }
}

6.接收用户输入的5门功课并且，计算平均分。（15分）

给用户评级60-80良，81-90好，91-100优秀。

public class Test05 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double array[]=new double[5];
        System.out.println("请输入5门功课的成绩");
        double sum = 0;// 定义分数总和值
        double avg = 0;// 定义平均分值
        for (int i = 0; i <5; i++) {
        System.out.print("请输入" + (i + 1)+ "第门成绩：");
           array[i] = scanner.nextDouble();
           sum+=array[i];
        }
        avg = sum / array.length;// 求得平均分值
        String rank = avg >=91 ? "优秀" : (avg >=81 ? "好" : (avg >=60) ? "良"
                : "");
        System.out.println("五门科目的平均分是：" + avg+" 评级为：" + rank);
        scanner.close();
    }
}

7.创建一个面积类，可以计算长方形，圆形的面积。并在DEMO类测试，计算长方形面积，圆的面积。（15分）

public class Circele{
    private double radius = 0;// 圆的半径
    public Circele(double radius){// 通过构造方法，获得半径
        this.radius = radius;
    }
    //获得圆形面积
    double getArea() {
        return Math.PI * radius * radius;
    }
}

public class Rectangle {
    private double height=0;
    private double weigtht=0;
    public Rectangle(double height,double weigtht){
      this.height=height;
      this.weigtht=weigtht;
    }
    double getarea(){
        return height*weigtht;
    }
}

public class Demo {
    public static void main(String[] args) {
        Circele circele = new Circele(10);
        System.out.println("圆的面积是："+circele.getArea());
        Rectangle rectangle = new Rectangle(10, 4);
        System.out.println("长方形面积是："+rectangle.getarea());
    }
}

8.判断200-300之间有多少个素数，并输出所有素数。

程序分析：判断素数的方法：用一个数分别去除2到sqrt(这个数)，如果能被整除，则表明此数不是素数，反之是素数。

public class suShu {
    public static void main(String[] args) {
        int sum = 0;
        for (int i = 200; i<= 300; i++)
        {
            boolean isFind = false;
            for (int j= 2; j <i; j++)
            {
                if (i%j==0)
                {
                    isFind = true;
                    break;
                }
             }
            if (!isFind)
            {
                System.out.println(i);
                sum += i;
            }
        }
        System.out.println("200到300之间的质数之和是："+sum);
    }
}

9.输入一行字符，分别统计出其中英文字母、空格、数字和其它字符的个数。

 程序分析：利用while语句,条件为输入的字符不为' '.

 public class CountAll {
    public static void main(String[] args){

        System.out.print("请输入一串字符：");

        Scanner scan = new Scanner(System.in);

        String str = scan.nextLine();//将一行字符转化为字符串

        scan.close();

        count(str);

    }

//统计输入的字符数

    private static void count(String str){

        String E1 = "[u4e00-u9fa5]";//汉字

        String E2 = "[a-zA-Z]";

        String E3 = "[0-9]";

        String E4 = "\s";//空格

        int countChinese = 0;

        int countLetter = 0;

        int countNumber = 0;

        int countSpace = 0;

        int countOther = 0;

        char[] array_Char = str.toCharArray();//将字符串转化为字符数组

        String[] array_String = new String[array_Char.length];//汉字只能作为字符串处理

        for(int i=0;i<array_Char.length;i++) {

            array_String[i] = String.valueOf(array_Char[i]);
        }

//遍历字符串数组中的元素

        for(String s:array_String){

            if(s.matches(E1)) {

                countChinese++;

            }else if(s.matches(E2)) {

                countLetter++;

            }else if(s.matches(E3)){

                countNumber++;

            }else if(s.matches(E4)) {

                countSpace++;

            }else
                countOther++;
        }

        System.out.println("输入的汉字个数："+countChinese);

        System.out.println("输入的字母个数："+countLetter);

        System.out.println("输入的数字个数："+countNumber);

        System.out.println("输入的空格个数："+countSpace);

        System.out.println("输入的其它字符个数："+countSpace);

    }
}

10.求s=a+aa+aaa+aaaa+aa...a的值，其中a是一个数字。例如2+22+222+2222+22222(此时共有5个数相加)，几个数相加有键盘控制。

public class Sum {
    public static void main(String[] args){

        System.out.print("求s=a+aa+aaa+aaaa+...的值，请输入a的值：");

        Scanner scan = new Scanner(System.in).useDelimiter("\s*");//以空格作为分隔符

        int a = scan.nextInt();

        int n = scan.nextInt();

        scan.close();//关闭扫描器

        System.out.println(expressed(2,5)+add(2,5));

    }

//求和表达式

    private static String expressed(int a,int n){

        StringBuffer sb = new StringBuffer();

        StringBuffer subSB = new StringBuffer();

        for(int i=1;i<n+1;i++){

            subSB = subSB.append(a);

            sb = sb.append(subSB);

            if(i<n)

                sb = sb.append("+");

        }

        sb.append("=");

        return sb.toString();

    }

//求和

    private static long add(int a,int n){

        long sum = 0;

        long subSUM = 0;

        for(int i=1;i<n+1;i++){

            subSUM = subSUM*10+a;

            sum = sum+subSUM;

        }

        return sum;

    }
}

11.输入某年某月某日，判断这一天是这一年的第几天？

程序分析：以3月5日为例，应该先把前两个月的加起来，然后再加上5天即本年的第几天，特殊情况，闰年且输入月份大于3时需考虑多加一天。

public class WhichDay {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in).useDelimiter("\D");//匹配非数字
        System.out.println("请输入当前日期（年-月-日：");
        int year = scan.nextInt();
        int month = scan.nextInt();
        int date = scan.nextInt();
        scan.close();
        System.out.println("今天是"+year+"年的第"+analysis(year,month,date)+"天");
    }
    private static int analysis(int year, int month,int date){

        int n = 0;

        int[] month_date = new int[] {0,31,28,31,30,31,30,31,31,30,31,30};

        if((year%400)==0 || ((year%4)==0)&&((year%100)!=0))

            month_date[2] = 29;

        for(int i=0;i<month;i++)

            n += month_date[i];

        return n+date;

    }
}

12.输入三个整数x,y,z，请把这三个数由小到大输出

程序分析：我们想办法把最小的数放到x上，先将x与y进行比较，如果x>y则将x与y的值进行交换，然后再用x与z进行比较，如果x>z则将x与z的值进行交换，这样能使x最小

public class Compare {
    public static void main(String[] args){

        Scanner scan = new Scanner(System.in).useDelimiter("\D");

        System.out.print("请输入三个数：");

        int x = scan.nextInt();

        int y = scan.nextInt();

        int z = scan.nextInt();

        scan.close();

        System.out.println("排序结果："+sort(x,y,z));

    }

//比较两个数的大小

    private static String sort(int x,int y,int z){

        String s = null;

        if(x>y){

            int t = x;

            x = y;

            y = t;

        }

        if(x>z){

            int t = x;

            x = z;

            z = t;

        }

        if(y>z){

            int t = z;

            z = y;

            y = t;

        }

        s = x+" "+y+" "+z;

        return s;

    }
    }

13.求1+2!+3!+...+20!的和

程序分析：此程序只是把累加变成了累乘。

public class ForTest {
    public static void main(String[] args){
    int x=1;
    int sum=0;
     for (int i = 1; i <=20 ; i++) {
        x=x*i;
        sum+=x;
        }
        System.out.println(sum);
    }
}

14.利用递归方法求5!

程序分析：递归公式：fn=fn_1*4!

public class Fn {
    public static void main(String[] args) {
        System.out.println(fact(10));
    }
    //递归阶乘公式
    private  static  long fact(int n){
     if(n==1){
         return 1;
     }else {
         return fact(n-1)*n;
     }
    }
}

15.请输入星期几的第一个字母来判断一下是星期几，如果第一个字母一样，则继续 判断第二个字母。

程序分析：用情况语句比较好，如果第一个字母一样，则判断用情况语句或if语句判断第二个字母。

public class Week {
    public static void main(String[] args){

        String str = new String();

        BufferedReader bufIn = new BufferedReader(new InputStreamReader(System.in));

        System.out.print("请输入星期的英文单词前两至四个字母）：");

        try{

            str = bufIn.readLine();

        }catch(IOException e){

            e.printStackTrace();

        }finally{

            try{

                bufIn.close();

            }catch(IOException e){

                e.printStackTrace();

            }

        }

        week(str);

    }

    private static void week(String str){

        int n = -1;

        if(str.trim().equalsIgnoreCase("Mo") || str.trim().equalsIgnoreCase("Mon") || str.trim().equalsIgnoreCase("Mond"))

            n = 1;

        if(str.trim().equalsIgnoreCase("Tu") || str.trim().equalsIgnoreCase("Tue") || str.trim().equalsIgnoreCase("Tues"))

            n = 2;

        if(str.trim().equalsIgnoreCase("We") || str.trim().equalsIgnoreCase("Wed") || str.trim().equalsIgnoreCase("Wedn"))

            n = 3;

        if(str.trim().equalsIgnoreCase("Th") || str.trim().equalsIgnoreCase("Thu") || str.trim().equalsIgnoreCase("Thur"))

            n = 4;

        if(str.trim().equalsIgnoreCase("Fr") || str.trim().equalsIgnoreCase("Fri") || str.trim().equalsIgnoreCase("Frid"))

            n = 5;

        if(str.trim().equalsIgnoreCase("Sa") || str.trim().equalsIgnoreCase("Sat") || str.trim().equalsIgnoreCase("Satu"))

            n = 2;

        if(str.trim().equalsIgnoreCase("Su") || str.trim().equalsIgnoreCase("Sun") || str.trim().equalsIgnoreCase("Sund"))

            n = 0;

        switch(n){

            case 1:

                System.out.println("星期一");

                break;

            case 2:

                System.out.println("星期二");

                break;

            case 3:

                System.out.println("星期三");

                break;

            case 4:

                System.out.println("星期四");

                break;

            case 5:

                System.out.println("星期五");

                break;

            case 6:

                System.out.println("星期六");

                break;

            case 0:

                System.out.println("星期日");

                break;

            default:

                System.out.println("输入有误！");

                break;

        }

    }
}

16.100之内的素数

程序分析：素数是不能被1或者它本身之外的其他数整除的整数

public class Sushu {
    public static void main(String[] args) {
        int i,j;
        for ( i = 1; i <=100;i++) {
            for ( j =2; j <i ; j++) {
              if ((i%j)==0){
                  break;
              }
            }
            if (i==j){
                System.out.println(i);
            }
        }
    }
}

17.输入3个数a,b,c，按大小顺序输出。

public class ThreeNumber {
    public static void main(String[] args){

        System.out.print("请输入3个数：");

        Scanner scan = new Scanner(System.in).useDelimiter("\s");

        int a = scan.nextInt();

        int b = scan.nextInt();

        int c = scan.nextInt();

        scan.close();
        if(a<b){
            int t = a;
            a = b;
            b = t;
        }
        if(a<c){
            int t = a;
            a = c;
            c = t;
        }
        if(b<c){
            int t = b;
            b = c;
            c = t;
        }
        System.out.println(a+" "+b+" "+c);
    }
}

18.写一个函数，求一个字符串的长度，在main函数中输入字符串，并输出其长度。

//注意：next()方法读取到空白符就结束了,nextLine()读取到回车结束也就是“ ”；
public class StringLenth {
    public static void main(String[] args) {
        System.out.print("请输入一行字符串:");
        Scanner scanner = new Scanner(System.in).useDelimiter("\n");
        String str = scanner.nextLine();
        scanner.close();
        //将字符串转化为字符数组
        char[]chars=str.toCharArray();
        System.out.println(str+"共"+(chars.length-1)+"个字符");

    }
}

19.对字符串的排序

public class letter {
    public static void main(String[] args){

        String[] str = {"abc","cad","m","fa","f"};

        for(int i=str.length-1;i>=1;i--){

            for(int j=0;j<=i-1;j++){

                if(str[j].compareTo(str[j+1])<0){

                    String temp = str[j];

                    str[j] = str[j+1];

                    str[j+1] = temp;

                }

            }
        }

        for(String subStr:str)

            System.out.print(subStr+" ");

    }
}

20.两个字符串连接程序

public class Connection {
    public static void main(String[] args) {
        String str1="你好,";
        String str2="世界欢迎你！";
        String str=str1+str2;
        System.out.println(str);
    }
}

21.统计字符串中子串出现的次数

public class Character {
    public static void main(String[] args){
        String str = "I come from China";
        char[] ch = str.toCharArray();
        int count = 0;
        for(int i=0;i<ch.length;i++){
            if(ch[i]==' ')
                count++;
        }
        count++;
        System.out.println("共有"+count+"个字串");
    }
}

22.有五个学生，每个学生有3门课的成绩，从键盘输入以上数据（包括学生号，姓名，三门课成绩），计算出平均成绩，将原有的数据和计算出的平均分数存放在磁盘文件"stud"中。

public class Student {
     //定义学生数组模型
    String[] number = new String[5];
    String[] name = new String[5];
    float[][] grade = new float[5][3];
    float[] sum = new float[5];

    /**
     * 输入学号、姓名、成绩
     */
    void input() throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        //录入状态标识
        boolean isRecord=true;
        while (isRecord){
            try {
            for (int i = 0; i <5 ; i++) {
                System.out.print("请输入学号：");
                number[i]=br.readLine();
                System.out.print("请输入姓名：");
                name[i] = br.readLine();
                for (int j = 0; j <3; j++) {
                System.out.print("请输入第"+(j+1)+"门课成绩：");
                grade[i][j] = Integer.parseInt(br.readLine());
                }
                System.out.println();
                sum[i] = grade[i][0]+grade[i][1]+grade[i][2];
            }
                isRecord=false;
            }catch (Exception e){
                System.out.print("请输入数字!");
            }
        }
    }

     /**
     * 输出文件内容
     * @param
     */
    void output() throws IOException {
        FileWriter fw = new FileWriter("E:\Me\我的下载\stud.txt");
        BufferedWriter bw = new BufferedWriter(fw);
        bw.write("No.  "+"Name  "+"grade1  "+"grade2  "+"grade3  "+"average");
        //换行
        bw.newLine();
        for (int i = 0; i <5; i++) {
         bw.write(number[i]);
            for (int j = 0; j <3 ; j++) {
                bw.write(" "+grade[i][j]);
                bw.write(" "+sum[j]/5);
                bw.newLine();
            }
        }
        bw.close();
    }

    public static void main(String[] args) throws IOException {
        Student student = new Student();
        student.input();
        student.output();
    }
}

23.从硬盘中复制一个文件内容到另一个文件中

public class FileCopy {
    public static void main(String[] args) {
      copyAToB();
    }
    public static void copyAToB(){
        File file=new File("E:/Me/我的下载/stud.txt");
        File file2=new File("E:/Me/我的下载/b.txt");
        if(!file2.exists()){
            try {
                file2.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        InputStream in=null;
        OutputStream out=null;
        try {
            in=new FileInputStream(file);//建立到a的流
            out=new FileOutputStream(file2);//建立到b的流
            int i;
            while((i=in.read())!=-1){//从a读取字母
                out.write(i);//将字母写到b里
            }
            System.out.println("复制成功！");

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            try {
                out.close();
                in.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    }
}

 参考资料：https://blog.csdn.net/wenzhi20102321/article/details/52430616

https://blog.csdn.net/cao2219600/article/details/80973336