Java Learning Diary-basis-the remainder operation of random array

Time is May 6, 2017, Youth Day just past, the coordinates of Shanghai and Shanghai Drift 2 months.

Let's start with the brief. By:slowcity

"Case Study 1"

Requires the definition of an int array A, containing 100 elements, to hold 100 random 4-digit numbers. Then define an int type array B, which consists of 10 elements. Statistics a array of elements to 10 to find the remainder equals 0 of the number, save to b[0], 10 for the remainder equals 1 of the number, saved to b[1], ... And so on

Generally see this kind of the most basic idea:
1 Create a random four-digit number with an array  
2 retrieving an array, counting the conditional operations  

4 Output Print new array
The beginning of my-Rookie beginner's idea: Read the code feel too upright boy

1 Import Java.util.Random;

2  Public classDemo1 {3      Public Static  voidMain (String[]args) {4         inta[]=New int[100];5         intB1=0, b2=0,b3=0,b4=0,b5=0,b6=0,b7=0,b8=0,b9=0,b10=0;6          for(inti=0;i<a.length;i++){7             intmax=9999;//generates 100 4-bit random numbers and saves them in an array8                 intmin=1000;9Random random =NewRandom ();Ten                 ints = random.nextint (max)% (max-min+1) +min; Onea[i]=s;  ASystem.out.print (a[i]+ ""); -             if(A[i]/10==0) {//adds an array of elements to the 10 remainder operation and counts -b1++; the System.out.print (B1); -}Else if(a[i]%10==1){ -b2++; -}Else if(a[i]%10==2){ +b3++; -}Else if(a[i]%10==3){ +b4++; A}Else if(a[i]%10==4){ atb5++; -}Else if(a[i]%10==5){ -b6++; -}Else if(a[i]%10==6){ -b7++; -}Else if(a[i]%10==7){ inb8++; -}Else if(a[i]%10==8){ tob9++; +}Else if(a[i]%10==9){ -b10++; the                 } *         } $         intb[]=New int[10];//defining a new array, storing the countPanax Notoginsengb[0]=B1; -b[1]=B2; theb[2]=B3; +b[3]=b4; Ab[4]=b5; thed[s]=b6; +b[6]=B7; -b[7]=B8; $b[8]=B9; $b[9]=B10; -          for(intj=0;j<b.length;j++){ -System.out.println (B[j]);//use a For loop to print a new array the         }  -     }Wuyi}

After optimization

"Optimize One"
In comparison, the length of the code is less more than half, the algorithm is more logical
1  Public classDemo2 {2      Public Static voidMain (String[]args) {3         inta[]=New int[100];//declaring an array of length 100 a4         intb[]=New int[10];//declaring an array of length 10 B5          for(inti=0;i<a.length;i++) {//generate 4-bit numbers, stored in a array6A[i]= (int) (10000*math.random ());7         }8          for(intj=0;j<b.length;j++) {//Loop Body Nesting9             intSum=0;Ten              for(inti=0;i<a.length;i++){     One                 if(a[i]%10==j) { Asum++; -                 } -             } theb[j]=sum;  -System.out.println (B[j]);//Print Array b -         } -     } +}

"Optimize two"

1 ImportJava.util.Random;2 3  Public classradomdemo{4      Public Static voidMain (string[] args) {5         int[] A=New int[100];6         int[] b=New int[10];7Random ran=NewRandom (); Define the Run method-Generate random numbers8         intIndex=0;9          while(index<100) {//use while for conditional filteringTen             inttmp=Ran.nextint (); Generates a random number, and the filter---here is much slower when the code runs One             if((tmp<=9999&&tmp>=1000)){ Aa[index]=tmp; To store a filtered random number -Index + +; - SYSTEM.OUT.PRINTLN (TMP); The output here is not necessary the             }             -         } -System.out.println ("-----------------------------------"); -          for(intj=0;j<10;j++) {//Nested loops +             intNum=0; -          for(inti:a) {//for-each Enhanced statement, traversing array +             if(i%10==j) {             Anum++; at             } -         } -b[j]=num; Assign a count result to data b - System.out.println (B[j]); -         }             -     }     in}

Learning Summary: The method is very important, the most important is to simplify the algorithm, condensed code.

Java Learning Diary-basis-the remainder operation of random array