Java |如何创建自己的助手类？-yiteyi-C++库

Helper类是一个Java类，它包括基本的错误处理、一些Helper函数等。Helper类包含帮助程序的函数。这个类旨在快速实现基本函数，这样程序员就不必一次又一次地实现。它很容易访问，因为所有成员函数都是静态的，也就是说，它可以从任何地方访问。它实现了最常用的函数，不包括java库中已经存在的函数。

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根据程序的需要，不同的助手类包含不同的方法。

建议：为这个类命名HelperClass制作一个包，并导入java代码

下面是helperclass的一个示例。

                     // Example for helper class                   
                     import                               java.lang.*;                   
                     import                               java.util.*;                   
                             
                     class                               HelperClass {                   
                             
                                         // to check whether integer is greater than 0 or not                   
                                         // usually used when we have to input a whole number                   
                                         // like taking input of number of test cases etc                   
                                         public                               static                               boolean                               isValidInteger(                               int                               test)                   
                                         {                   
                                         return                               (test >=                               0                               );                   
                                         }                   
                             
                                         // to check whether integer is greater than the lower                   
                                         //  bound and lower than the highest bound.                   
                                         public                               static                               boolean                               isValidInteger(                               int                               test,                               int                               low,                   
                                         int                               high) {                   
                                         return                               (test >= low && test <= high);                   
                                         }                   
                             
                                         // used when we want the user to input the number                   
                                         // exactly greater than the lower bound                   
                                         public                               static                               int                               getInRange(                               int                               low) {                   
                                         Scanner sc =                               new                               Scanner(System.in);                   
                                         int                               test;                   
                                         do                   
                                         {                   
                                         test = sc.nextInt();                   
                                         }                               while                               (test < low);                   
                             
                                         return                               test;                   
                                         }                   
                             
                                         // used when we want the user to input the number                   
                                         // exactly greater than lower bound and lower than                   
                                         // the highest bound                   
                                         public                               static                               int                               getInRange(                               int                               low,                               int                               high) {                   
                                         Scanner sc =                               new                               Scanner(System.in);                   
                                         int                               test;                   
                                         do                               {                   
                                         test = sc.nextInt();                   
                                         }                               while                               (test < low || test > high);                   
                                         return                               test;                   
                                         }                   
                             
                                         // to check whether an array contains any negative value                   
                                         public                               static                               boolean                               validatePositiveArray(                               int                               [] array,                   
                                         int                               n) {                   
                                         for                               (                               int                               i =                               0                               ; i < n; i++)                   
                                         if                               (array[i] <                               0                               )                   
                                         return                               false                               ;                   
                                         return                               true                               ;                   
                                         }                   
                             
                                         // to check whether an array contains any positive value                   
                                         public                               static                               boolean                               validateNegativeArray(                               int                               [] array,                   
                                         int                               n) {                   
                                         for                               (                               int                               i =                               0                               ; i < n; i++)                   
                                         if                               (array[i] >                               0                               )                   
                                         return                               false                               ;                   
                                         return                               true                               ;                   
                                         }                   
                             
                                         // check whether every element in the array is greater                   
                                         // than the lower bound                   
                                         public                               static                               boolean                               checkRangeArray(                               int                               [] array,                   
                                         int                               n,                               int                               low) {                   
                                         for                               (                               int                               i =                               0                               ; i < n; i++)                   
                                         if                               (array[i] < low)                   
                                         return                               false                               ;                   
                                         return                               true                               ;                   
                                         }                   
                             
                                         // check whether every element in the array is greater                   
                                         // than the lower bound and lower than the highest bound                   
                                         public                               static                               boolean                               checkRangeArray(                               int                               [] array,                               int                               n,                   
                                         int                               low,                               int                               high) {                   
                                         for                               (                               int                               i =                               0                               ; i < n; i++)                   
                                         if                               (array[i] < low || array[i] > high)                   
                                         return                               false                               ;                   
                                         return                               true                               ;                   
                                         }                   
                             
                                         // check whether two given sets as "arrays" are equal or not                   
                                         public                               static                               boolean                               isEqualSets(                               int                               [] array1,                               int                               n,                   
                                         int                               [] array2,                               int                               m) {                   
                                         if                               (n != m)                   
                                         return                               false                               ;                   
                                         HashMap<Integer, Integer> Map =                   
                                         new                               HashMap<Integer, Integer>();                   
                                         for                               (                               int                               i =                               0                               ; i < n; i++)                   
                                         Map.put(                               new                               Integer(array1[i]),                               new                               Integer(                               1                               ));                   
                                         for                               (                               int                               i =                               0                               ; i < m; i++)                   
                                         Map.put(                               new                               Integer(array2[i]),                               new                               Integer(                               0                               ));                   
                             
                                         for                               (                               int                               i =                               0                               ; i < n; i++)                   
                                         if                               (Map.get(array1[i]) ==                               1                               )                   
                                         return                               false                               ;                   
                                         return                               true                               ;                   
                                         }                   
                             
                                         // calculating factorial of a number                   
                                         public                               static                               String factorial(                               int                               n) {                   
                                         String fact =                               new                               String(                               ""                               );                   
                                         int                               res[] =                               new                               int                               [                               500                               ];                   
                             
                                         res[                               0                               ] =                               1                               ;                   
                                         int                               res_size =                               1                               ;                   
                             
                                         for                               (                               int                               x =                               2                               ; x <= n; x++)                   
                                         res_size = multiply(x, res, res_size);                   
                             
                                         for                               (                               int                               i = res_size -                               1                               ; i >=                               0                               ; i--)                   
                                         fact += Integer.toString(res[i]);                   
                             
                                         return                               fact;                   
                                         }                   
                             
                                         // Multiply x  with res[0..res_size-1]                   
                                         public                               static                               int                               multiply(                               int                               x,                               int                               res[],                               int                               res_size) {                   
                                         int                               carry =                               0                               ;                   
                                         for                               (                               int                               i =                               0                               ; i < res_size; i++) {                   
                                         int                               prod = res[i] * x + carry;                   
                                         res[i] = prod %                               10                               ;                   
                                         carry = prod /                               10                               ;                   
                                         }                   
                                         while                               (carry !=                               0                               ) {                   
                                         res[res_size] = carry %                               10                               ;                   
                                         carry = carry /                               10                               ;                   
                                         res_size++;                   
                                         }                   
                                         return                               res_size;                   
                                         }                   
                             
                                         // Checks whether the given number is prime or not                   
                                         public                               static                               boolean                               isPrime(                               int                               n) {                   
                                         if                               (n ==                               2                               )                   
                                         return                               true                               ;                   
                             
                                         int                               squareRoot = (                               int                               )Math.sqrt(n);                   
                                         for                               (                               int                               i =                               1                               ; i <= squareRoot; i++)                   
                                         if                               (n % i ==                               0                               && i !=                               1                               )                   
                                         return                               false                               ;                   
                                         return                               true                               ;                   
                                         }                   
                             
                                         // Returns nthPrimeNumber                   
                                         public                               static                               int                               nthPrimeNumber(                               int                               n) {                   
                                         int                               k =                               0                               ;                   
                                         for                               (                               int                               i =                               2                               ;; i++) {                   
                                         if                               (isPrime(i))                   
                                         k++;                   
                                         if                               (k == n)                   
                                         return                               i;                   
                                         }                   
                                         }                   
                             
                                         // check whether the given string is palindrome or not                   
                                         public                               static                               boolean                               isPalindrome(String test) {                   
                                         int                               length = test.length();                   
                                         for                               (                               int                               i =                               0                               ; i <= (test.length()) /                               2                               ; i++)                   
                                         if                               (test.charAt(i) != test.charAt(length - i -                               1                               ))                   
                                         return                               false                               ;                   
                                         return                               true                               ;                   
                                         }                   
                             
                                         // check whether two strings are anagram or not                   
                                         public                               static                               boolean                               isAnagram(String s1, String s2) {                   
                             
                                         // Removing all white spaces from s1 and s2                   
                                         String copyOfs1 = s1.replaceAll(                               "\s"                               ,                               ""                               );                   
                                         String copyOfs2 = s2.replaceAll(                               "\s"                               ,                               ""                               );                   
                             
                                         if                               (copyOfs1.length() != copyOfs2.length())                   
                                         return                               false                               ;                   
                             
                                         // Changing the case of characters of both copyOfs1 and                   
                                         // copyOfs2 and converting them to char array                   
                                         char                               [] s1Array = copyOfs1.toLowerCase().toCharArray();                   
                                         char                               [] s2Array = copyOfs2.toLowerCase().toCharArray();                   
                             
                                         // Sorting both s1Array and s2Array                   
                                         Arrays.sort(s1Array);                   
                                         Arrays.sort(s2Array);                   
                             
                                         // Checking whether s1Array and s2Array are equal                   
                                         return                               (Arrays.equals(s1Array, s2Array));                   
                                         }                   
                     }                               /*** end of helperClass **/                   
                             
                     class                               Test {                   
                                         public                               static                               void                               main(String[] args) {                   
                             
                                         int                               n = -                               5                               ;                   
                                         if                               (HelperClass.isValidInteger(n))                   
                                         System.out.println(                               "True"                               );                   
                                         else                   
                                         System.out.println(                               "False"                               );                   
                             
                             
                                         String str =                               "madam"                               ;                   
                                         if                               (HelperClass.isPalindrome(str))                   
                                         System.out.println(                               "True"                               );                   
                                         else                   
                                         System.out.println(                               "False"                               );                   
                                         }                   
                     }                   

False
True

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