韩顺平老师的Java练习题 大家可以尝试着做一做

package exer;

public class Demo01 {
    public static void main(String[] args) {
        double total = 100000d;
        int count=0;
        while(true){
            if (total > 50000) {
                total = total*0.95;
                count++;
            }else if (total<=50000){
                total = total-1000;
                count++;
            } else if (total<1000) {
                break;
            }
        }
        System.out.println(count);
    }
}

import java.util.Scanner;
public class Demo02 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入一个整数");
        String str = null;
        do{
            int num = scanner.nextInt();
            if (num>0){
                System.out.println("大于0");
            } else if (num<0) {
                System.out.println("小于0");
            }else {
                System.out.println("等于0");
            }
            System.out.println("no退出/任意字母继续");
            str = scanner.next();
        }while(!str.equals("no"));
        scanner.close();
    }
}}

import java.util.Scanner;

public class Demo03 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int year = scanner.nextInt();
        if((year%4==0&&year%100==0)||(year%400==0)){
            System.out.print("是闰年");
        }
        scanner.close();
    }
}

public class Demo03 {
    public static void main(String[] args) {
        int num = 153;
        int x = num%10/1;//个
        int y = num%100/10;//十
        int z = num/100;//百
        if(num==(x*x*x+y*y*y+z*z*z)){
            System.out.println("水仙花数");
        }
    }
}

//作业6
public class Demo04 {
    public static void main(String[] args){
        int flag = 0;
        for (int i =1;i<=100;i++){
            if(i%5!=0){
                System.out.print(i+"\t");
                flag++;
            }
            if (flag==5){   //flag%5==0也可以
                System.out.println();
                flag=0;
            }
        }
    }
}

//作业7
public class Demo05 {
    public static void main(String[] args) {
        for (char c1 = 'a';c1<='z';c1++){
            System.out.print(c1);
        }
        System.out.println();
        for(char c2='Z';c2>='A';c2--){
            System.out.print(c2);
        }
    }
}

//作业8
public class Demo06 {
    public static void main(String[] args) {
        double first=0;
        for(int i =1;i<=100;i++){
            if(i%2==0){
                first=first-(1.0/i);
            }else{
                first=first+(1.0/i);
            }
        }
        System.out.print(first);
    }
}

//作业9
public class Demo07 {
    public static void main(String[] args) {
    //1 3 6 10 15 21

        int front= 0;
        int sum = 0;
        int total = 0;
        for (int i =1;i<=100;i++){
           sum = sum+i;
           total = sum+front;
           front = total;//将前几个合赋给front
        }
        System.out.print(total);
    }
}

 

 第一段代码是我自己的想法，第二段是老师的，老师的比较简洁，还是大佬牛逼

public class Demo10 {
    public static void main(String[] args) {
        int[] arrays = {10,12,45,90,100,102};
        int[] arrays1 = new int[arrays.length+1];
        int num =8;
        if (num<arrays[0]){
            arrays1[0] = num;
            for (int i =0;i<arrays.length;i++){
                arrays1[i+1]=arrays[i];
            }
        } else if (num>arrays[arrays.length-1]) {
            arrays1[arrays1.length-1] = num;
            for (int i =0;i<arrays.length;i++){
                arrays1[i]=arrays[i];
            }
        }else{
            int index=-1;
            for (int i=0;i<arrays.length;i++){
                if(arrays[i]>=num){//找到定位点
                    index = i;
                    arrays1[index] = num;
                    for (int j=index;j<arrays.length;j++){//定位点后的数赋值
                        arrays1[j+1] =arrays[j];
                    }
                    break;
                }else {
                    arrays1[i]=arrays[i];
                }
            }
        }
        printArray(arrays1);


    }
    public static void printArray(int[] arrays){
        for (int i=0;i<arrays.length;i++){
            System.out.print(arrays[i]+"\t");
        }
    }
}

public class Demo11 {
    public static void main(String[] args) {
        int[] arr ={10,12,45,90};
        int insertNum = 23;
        int index =-1; //作为定位索引
        //找定位点
        for (int i=0;i<arr.length;i++){
            if (arr[i]>=insertNum){
                index=i;
                break;//找直接跳出即可
            }
        }
        //判断index的值,-1则位找到,加入末尾即可
        if(index==-1){
            index=arr.length;
        }
        //扩容
        int[] arrNew = new int[arr.length+1];
        for (int i=0,j=0;i<arrNew.length;i++){
            if(i!=index){
                arrNew[i]=arr[j];
                j++;//神来之笔
            }else {
                arrNew[i]=insertNum;
            }
        }
        printArray(arrNew);
    }

    public static void printArray(int[] arrays){
        for (int i=0;i<arrays.length;i++){
            System.out.print(arrays[i]+"\t");
        }
    }
}