Java Learning Note 6 (loops and array exercises)

1. Output the number of daffodils from 100 to 1000:

 Public classlooptest{ Public Static voidMain (string[] args) {intBai = 0; intShi = 0; intGE = 0;  for(inti = 100; i < 1000; i++) {Bai= i/100; Shi= i/10%10; GE= i%10; if(Bai*bai*bai+shi*shi*shi+ge*ge*ge = =i)            {System.out.println (i); }        }    }}

2. Print all letters:

 Public class looptest{    publicstaticvoid  main (string[] args) {        Char lower = ' a ';         char upper = ' A ';          for (int i = 0; i <; i++) {            System.out.println (lower+ "   " +Upper);            Lower+ +;            Upper+ +;     }}}

3. Print the 99 multiplication table:

 Public class looptest{    publicstaticvoid  main (string[] args) {        for (int i = 1; I <=9; i++) {            for (int j = 1; j<=i; j + +) {
    system.out.print (J+ "*" +i+ "=" +j*i+ "    ");            }            System.out.println ();     }}}

4. Iterate through the array as a format:

 Public classarraytest{ Public Static voidMain (string[] args) {int[] arr1 = {4,6,7,1}; int[] arr2 = {1,2,3,9,10};        PrintArray (ARR1);    PrintArray (ARR2); }     Public Static voidPrintArray (int[] arr) {System.out.print ("[");  for(inti = 0; I <arr.length; i++){            if(i = = Arr.length-1) {System.out.println (Arr[i]+"]"); }Else{System.out.print (Arr[i]+","); }        }    }}

5. Reverse the array elements (note: not backward traversal):

 Public classarraytest{ Public Static voidMain (string[] args) {int[] arr = {1,2,3,4,7,8,9};        Reverse (arr);    PrintArray (arr); }     Public Static voidReverseint[] arr) {         for(intMin=0,max = arr.length-1; Min<max; min++,max--){            inttemp =Arr[min]; Arr[min]=Arr[max]; Arr[max]=temp; }    }      Public Static voidPrintArray (int[] arr) {System.out.print ("[");  for(inti = 0; I <arr.length; i++){            if(i = = Arr.length-1) {System.out.println (Arr[i]+"]"); }Else{System.out.print (Arr[i]+","); }        }    }}

6. Select Sort:

 Public classarraytest{ Public Static voidMain (string[] args) {int[] arr = {3,1,5,7,8,9,2};        Selectsort (arr);    PrintArray (arr); }     Public Static voidSelectsort (int[] arr) {         for(inti = 0; i < arr.length-1; i++){             for(intj = i+1; j<arr.length; J + +){                if(arr[i]>Arr[j]) {                    inttemp =Arr[i]; Arr[i]=Arr[j]; ARR[J]=temp; }            }        }    }     Public Static voidPrintArray (int[] arr) {System.out.print ("[");  for(inti = 0; I <arr.length; i++){            if(i = = Arr.length-1) {System.out.println (Arr[i]+"]"); }Else{System.out.print (Arr[i]+","); }        }    }}

7. Bubble Sort:

 Public classarraytest{ Public Static voidMain (string[] args) {int[] arr = {3,1,5,7,8,9,2};        Bubblesort (arr);    PrintArray (arr); }     Public Static voidBubblesort (int[] arr) {         for(inti = 0; i<arr.length-1; i++){             for(intj = 0; j<arr.length-i-1; J + +){                if(arr[j]>arr[j+1]){                    inttemp =Arr[j]; ARR[J]= Arr[j+1]; Arr[j+1] =temp; }            }        }    }     Public Static voidPrintArray (int[] arr) {System.out.print ("[");  for(inti = 0; I <arr.length; i++){            if(i = = Arr.length-1) {System.out.println (Arr[i]+"]"); }Else{System.out.print (Arr[i]+","); }        }    }}

8. Binary Lookup method (note must be an ordered array):

 Public classarraytest{ Public Static voidMain (string[] args) {int[] arr = {1,3,5,7,9,11}; intindex = BinarySearch (arr, 7);    SYSTEM.OUT.PRINTLN (index); }     Public Static intBinarySearch (int[] arr,intkey) {        intMin = 0; intmax = Arr.length-1; intMID = 0;  while(min<=max) {Mid= (Min+max)/2; if(key>Arr[mid]) {min= Mid+1; }Else if(key<Arr[mid]) {Max= Mid-1; }Else{                returnmid; }        }        return-1; }}

Java Learning Note 6 (loops and array exercises)