Question

它没有提供任何输出，但代码运行没有错误。我想显示所有方法，包括冒泡排序，选择排序和比较排序的结果？我该如何调用这些方法。当我运行它时，它不会给我任何输出。所以，我只需要帮助来运行代码。

  public static void main(String[] args) {
    int[] A = new int[100];
    int[] B = new int[100];
  }
//get a random number;

  private int getRand() {
    Random in = new Random();
    return in.nextInt(100);
  }
//fill an array with numbers from 0 to 99;

  public static void fillArray(int[] array) {
    for (int i = 0; i < array.length; i++) {
      array[i] = i;
    }
  }
//copy an array to another;

  public static void copyArray(int[] aArray, int[] bArray) {
    for (int i = 0; i < aArray.length; i++) {
      bArray[i] = aArray[i];
    }
  }
//swap two numbers in an array according to index;

  private void swap(int[] array, int i, int j) {
    int temp = array[i];
    array[i] = array[j];
    array[j] = temp;
  }
//random select two numbers in an array and switch them;

  int disorderArray(int[] array) {
    int i, j;
    i = getRand();
    j = getRand();
    swap(array, i, j);
    //System.out.println("the index of the 2 swapped numbers are " + i +  " " +     
    j
    );
    return i;
  }

//print out the array;
public static void printArray(int[] array, int col) {
    for (int i = 0; i < array.length - col + 1; i += col) {
        for (int j = i; j < i + col; j++)
            System.out.print("number " + j + " is " + array[j] + ";  ");
        System.out.println();
    }
    for (int i = array.length - array.length % col; i < array.length; i++)
        System.out.print("number " + i + " is " + array[i] + ";  ");
    System.out.println();
    System.out.println();
}

//bubble sort;
public void bubbleSort(int[] array) {
    for (int i = array.length - 1; i > 0; i--) {
        for (int j = 0; j < i; j++) {
            if (array[j] > array[j + 1])
                swap(array, j, j + 1);
        }
    }
}

//selection sort;
public void selectionSort(int[] array) {
    for (int i = 0; i < array.length - 1; i++) {
        int p = i;
        for (int j = i + 1; j < array.length; j++)
            if (array[p] > array[j])
                p = j;
        if (i != p)
            swap(array, i, p);
    }
}

//compare two arrays;
public static boolean compareArrays(int[] aArray, int[] bArray) {
    boolean s = true;
    int i = 0;
    if (aArray.length == bArray.length) {
        while (s && i < aArray.length) {
            if (aArray[i] != bArray[i])
                s = false;
            i++;
        }
    }
    return s;
}

}

Answer 1

您已经实现了一些方法，但您需要使用main方法调用它们，例如

public static void main(String[] args) {
  int[] A = new int[100];
  int[] B = new int[100];

  fillArray(A);
  // more method calls...
}

注意，您已实现了类（static）方法和实例（非静态）方法。你如何称呼它们的语义不同。如果您的程序是在名为Foo的类中实现的，则可以编写以下内容：

// method call to class method
Foo.fillArray();

// method call to instance metod requires an instance
Foo fooInstance = new Foo();
int randomNumber = fooInstance.getRand();

通常，您使用实例方法来操作实例变量和类方法来操作类变量，或者更常见的是作为不涉及状态的辅助方法。有关这方面的更多信息可以在Oracle Java教程的Understanding Class Members章节中找到（向下滚动到类方法）。

ArraySort没有显示？

1 个答案: