初学者 Java 控制循环未产生预期结果答案

【问题标题】：Beginner Java Controlled Loop Not Producing Expected Results初学者 Java 控制循环未产生预期结果
【发布时间】：2015-09-24 23:12:42
【问题描述】：

我正在尝试创建一个菱形（由星号制成），但是我似乎无法获得右下腿，不是吗？为什么我的代码不正确？提前致谢

import java.util.Scanner;
public class Diamond 
{
    public static void main(String[] args)
    {
        System.out.println("Enter the size of the diamond and press enter:");    
        Scanner kb = new Scanner(System.in);
        int N = kb.nextInt();

        for (int c0 = 1; c0 <= N; c0++)     // establishes the number of lines in the diamond                
        {

            for (int c1 = 0; c1 <= N-1-c0; c1++) System.out.print(" "); // establishes the number of spaces before each asterisk
            System.out.print("*");

            for (int c2 = 3; c2 <= c0*2; c2++) System.out.print(" "); //adds a space between both asterisks. This boolean check repeats for each line
            System.out.print("*");
            System.out.println();

        }

        for (int c0 = 1; c0 <= N; c0++)   // establishes the number of lines in the diamond                
        {

            for (int c1 = N; c1 >= N+2-c0; c1--) System.out.print(" "); // establishes the number of spaces before each asterisk
            System.out.print("*");

            for (int c2 = N*2; c2 >= c0+2; c2--) System.out.print(" "); //adds a space between both asterisks. This boolean check repeats for each line
            System.out.print("*");
            System.out.println();

        }

    }
}

【问题讨论】：

标签： java loops for-loop counter

【解决方案1】：

如果你提取一个方法，事情的可读性会高很多。但首先，

for (int c2 = N*2; c2 >= c0+2; c2--) System.out.print(" ");

应该是这样的

for (int c2 = 0; c2 < (N-c0)*2; c2++) System.out.print(" ");

或类似

static String getSpaces(int n) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < n; i++) {
        sb.append(' ');
    }
    return sb.toString();
}

你可以这样称呼它

for (int c0 = 0; c0 < N; c0++) {
    System.out.print(getSpaces(N - c0));
    System.out.print("*");
    System.out.print(getSpaces(c0 * 2));
    System.out.print("*");
    System.out.println();
}
for (int c0 = 1; c0 <= N; c0++) {
    System.out.print(getSpaces(c0));
    System.out.print("*");
    System.out.print(getSpaces((N - c0) * 2));
    System.out.print("*");
    System.out.println();
}

【讨论】：

这成功了。我还没有学习其他对象，但是你对我现有代码的修复成功了

【解决方案2】：

我稍微调整了你的程序...你需要做更多的工作来去掉一些额外的星号。至少它会给你更多的想法：

import java.util.Scanner;
public class Diamond 
{
    public static void main(String[] args)
    {
        System.out.println("Enter the size of the diamond and press enter:");    
        Scanner kb = new Scanner(System.in);
        int N = kb.nextInt();

        for (int c0 = 1; c0 <= N; c0++)     // establishes the number of lines in the diamond                
        {

            for (int c1 = 0; c1 <= N-1-c0; c1++) System.out.print(" "); // establishes the number of spaces before each asterisk
            System.out.print("*");

            for (int c2 = 3; c2 <= c0*2; c2++) System.out.print(" "); //adds a space between both asterisks. This boolean check repeats for each line
            System.out.print("*");
            System.out.println();

        }


        for (int i = N ; i >= 1; i--)
        {
              for (int j = 0; j < (N - i); j++)
                    System.out.print(" ");
              for (int j = 1; j <= i; j++)
                    System.out.print("*");
             for (int k = 1; k < i; k++)
                    System.out.print("*");
              System.out.println();
        }

    }
}

【讨论】：