Question

import java.util.Scanner;

public class ProgrammaD{
    public static void main(String[] args){
        Scanner keyboard= new Scanner(System.in);
        String sequence = args[0];
        char chars[] = new char[sequence.length()];

        for(int i = 0; i < sequence.length(); i++){
            chars[i] = sequence.charAt(i);
        }

        System.out.println("Insert a character");
        char car = keyboard.next().charAt(0);
        System.out.println("Insert an integer");
        int n = keyboard.nextInt();
        System.out.println("Original Array");

        for(int z = 0; z < sequence.length(); z++){
            System.out.println(chars[z]);
        }

        char chars2[] = MetodiD.occorrenzeContenuto(chars, n, car);
        System.out.println("Edited Array");

        for(int k = 0; k < sequence.length(); k++){
            System.out.println(chars2[k]);
        }

        boolean condition = false;
        char chars3[] = MetodiD.uniformaContenuto(chars, chars2);

        for(int x = 0; x < sequence.length(); x++){
            if(chars[x] == chars2[x]){
                condition = false;
            }
            else{
                condition = true;
            }
        }

        if(condition){
            for(int y = 0; y < sequence.length(); y++){
                System.out.println(chars3[y]);
            }
        }
    }
}

我无法执行最后一条if指令，我无法理解为什么。有人可以帮我解决这个问题吗？我希望程序打印MetodiD.uniformaContenuto（）中返回的数组，但我无法从此代码中获取任何内容。

这是另一个班级：

public class MetodiD{
    public static char[] occorrenzeContenuto(char par[], int a, char b){
        int contatore = 0;
            for(int i = 0; i < par.length; i++){
                if(par[i] != b){
                    contatore++;
                }else{
                }
            }
            if(contatore > a){
                for(int k = 0; k < par.length; k++){
                    if(par[k] != b){
                        par[k] = determinaCarattere(a, b);
                    }else{
                }
            }
            }else{
            }
        return par;
    }

    public static char determinaCarattere(int n, char b){
        int modificato;
            if(n%2==0){
                modificato = (int)b - n;
            }else{
                modificato = (int) b + n;
            }
        char modificato2 = (char)modificato;
        return modificato2;
    }

    public static char[] uniformaContenuto(char par1[], char par2[]){
        char rit[] = new char[par1.length];
            for(int y = 0; y < par1.length; y++){
                if(par1[y]<par2[y]){
                    rit[y] = par1[y];
                }else{
                    rit[y] = par2[y];
                }
            }
        return rit;
    }
}

Answer 1

chars 正在 occorrenzeContenuto 中设置，然后返回并分配给 chars2 ，因此它们将始终相等。尝试将此版本换成我已创建新阵列的版本，并在开始时将 par 参数复制到其中，然后将其用作返回值。

public static char[] occorrenzeContenuto(char par[], int a, char b){
char[] retVal = new char[par.length];
System.arraycopy(par,0,retVal,0,par.length);
int contatore = 0;
for(int i = 0; i < par.length; i++){
  if(par[i] != b){
    contatore++;
  }else{
  }
}
if(contatore > a){
  for(int k = 0; k < par.length; k++){
    if(par[k] != b){
      retVal[k] = determinaCarattere(a, b);
    }else{
    }
  }
}else{
}
return retVal; 
}

问题的原因是数组参数维护对原始实例的引用，就像对象那样，而不像char这样的单个原语的行为，如下所述：Java pass by reference

无法输入此if-else语句

1 个答案: