Question

我正在尝试打印我的方法calSum和calMean。我想得到类似的输出：

java RandomArray 8

0 9 5 3 5 6 0 8

总和：36

平均值：4.5

但是我得到了-用法：java RandomArray。示例：java RandomArray 5

我在printArray方法中做错了吗？或者是别的什么？对我代码中的错误的任何帮助都将非常有用。

    public class RandomArray {

private int[] numbers; //instance variable

/**
 *  Constructor
 *
 *The size of the array
 */
public RandomArray(int size){
    numbers = new int[size];
    for(int i=0; i<numbers.length;i++){
        numbers[i] = (int)(Math.random()*10); // a random number between 0-9
    }
}

/**
 *  a method to print the array elements
 */

public void printArray() {
    for (int i = 0; i < numbers.length; i++)
        System.out.print("Java Random array:"+ numbers);
        System.out.println("Sum:" + calSum());
        System.out.println("Mean:" + calMean());
}       

/**
 *  A method to calculate the sum of all elements
 *
 */
public int calSum(){
 int sum = 0;
 for (int value : numbers) {
     sum += value;
}
    return sum;

}

/**
 *  A method to calculate the mean of all elements
 *
 *@return    The mean
 */

public double calMean() {
    int sum = calSum();
    int length = numbers.length;

    return (double) sum / length;
}


/**
 *  a method to print the array elements in reverse order
 */
public void printReverse(){


}

/**
 *  A main method to test
 */
public static void main(String[] args) {
    // Check to see if the user has actually sent a paramter to the method
    if (args.length != 1){
        System.out.println("Usage: java RandomArray <NUM>. Example: java RandomArray 5");
        System.exit(-1);
    }

    // Create an instance of the class 
    RandomArray test = new RandomArray(Integer.parseInt(args[0]));


    // Print the array
    test.printArray();

    // Calculate the sum of all the values in the array and print it
    System.out.println("Sum: "+ test.calSum());

    // Calculate the mean of all the values in the array and print it
    System.out.println("Mean: "+ test.calMean());

    System.out.print("Reverse: ");
    test.printReverse();
}

 }

Answer 1

运行主类时，main方法接受类型为String的元素数组。

即使在IDE中运行调用，也要记住该调用看起来像java RandomArray arg1 arg2。数组包括java之后的所有元素，甚至包括RandomArray。

因此args将始终由至少1个元素组成。如果要使用值arg1，则需要获取args[1]而不是args[0]。

您的代码应类似于：

public static void main(String[] args) {
    // Check to see if the user has actually sent a paramter to the method
    if (args.length != 2){
        System.out.println("Usage: java RandomArray <NUM>. Example: java RandomArray 5");
        System.exit(-1);
    }

    // Create an instance of the class 
    RandomArray test = new RandomArray(Integer.parseInt(args[1]));

...

接下来，在打印generate数组时，您将不会获得预期的结果。检查注释中的链接，以了解如何正确打印阵列。

打印阵列方法

1 个答案: