java - 使用嵌套 for 循环的简单 Java 金字塔

Question

我在尝试找出一种使用用户输入创建金字塔的方法时遇到了很大的麻烦。它应该是这样的。

Enter a number between 1 and 9: 4
O
O
O
O
OOOO
OOOO 
OOOO 
OOOO
O
OO
OOO
OOOO

这就是我目前所拥有的

public static void main(String[] args) {
    int number;
    Scanner keyboard = new Scanner(System.in); 

    System.out.print("Enter a number between 1 and 9: ");
    number = keyboard.nextInt();

    for (int i = 1; i < 10; i++){
        for (int rows = number; number < i; rows++){
            System.out.print("O");
        }
        System.out.println();  
    }
}

我完全理解我想要完成的任务，但我不完全理解 for 循环是如何工作的。任何帮助将不胜感激，因为我完全迷失了!

Answer 1

基本上 for 循环的工作原理如下

// Take this example (and also try it)
for (int i = 0; i < 10; i++) 
{
   System.out.println(i);
}


// Explanation
for(int i = 0; // the value to start at  - in this example 0
    i < 10;    // the looping conditions - in this example if i is less than 10 continue 
               //         looping executing the code inclosed in the { }
               //         Once this condition is false, the loop will exit
    i++)       // the increment of each loop - in this exampleafter each execution of the
               //         code in the { } i is increments by one
{
   System.out.println(i);  // The code to execute
}

使用不同的起始值、条件和增量进行实验，尝试这些:

for (int i = 5; i < 10; i++){System.out.println(i);}
for (int i = 5; i >  0; i--){System.out.println(i);}