Java 将字符串填充到任意长度的方法

我在计算如何填充从数组值打印的字符串时遇到问题。我认为我有一个很好的方法，但是它不能正确地读取x.length，所以我很好奇其他的方法，甚至是错误的解释

import java.util.Scanner;
//================================================================
public class Array {
//----------------------------------------------------------------
    private static Scanner Keyboard = new Scanner(System.in);

    public static void main(String[] args) {
    //----------------------------------------------------------------
        char group, rLetter,letter;
        String choice ;
        String str = " ";
        double sum     =  0;
        int num     = 10; // for test
        int rows    = 10;
        int columns =  8;
        double average = 0;
        int S;
        int diff = 0;
        int totalChar=0;
        int minLen = 20;
        String x= "";

        // creating 2d array


        System.out.print("Please enter number of rows               : ");
        rows = Keyboard.nextInt();
        Keyboard.nextLine();


        double[][] figures = new double[rows][num];

        for(int t = 0; t < rows; t++) { 
            rLetter = (char)((t)+'A');
            System.out.print("Please enter number of positions in row " + rLetter + " : "); 
                columns = Keyboard.nextInt(); 
                Keyboard.nextLine(); 

            figures[t] = new double[columns]; 
        }

        // filling the array
        for(int row = 0; row < figures.length; ++row) {
            for(int col = 0; col < figures[row].length; ++col) {
                figures[row][col] = 0.0;
            }
        }

        // printing the array
        for(int row=0; row<figures.length; ++row) {
            // printing data row
            group = (char)((row)+(int)'A');
            System.out.print(group+" : ");
            for(int col=0; col<figures[row].length; ++col) {
                sum += figures[row][col];
                average = sum/figures[row].length;

                x = "   "+figures[row][col];
                diff = minLen - x.length();
                System.out.printf("%1$" + diff + "s", x);

                System.out.print(" ");

            }
            System.out.print("["+average+"]");
            System.out.println();


}
}
}

其中-是我想用空格填充到任意长度的地方。换句话说，我希望我的打印数组部分能够打印每一行，并将空格添加到一个点。有没有可能为此制定一个方法？我还不太熟悉所有的java方法，因此非常感谢您的帮助。

---

如果这是一个重复的问题，我会很感激重定向到原来的，我会尝试删除这一个。也很抱歉给您带来不便。

我假设您知道如何使用

StringBuilder

或字符串连接在左侧和右侧构建字符串

构建字符串后，可以使用下面的

printf

在右侧将输出填充到所需的任意多个空白字符。在下面的示例代码中，我使用了

20

作为要填充的字符数

public class Pad {
    public static void main(String[] args) {
        String a = "0.0 0.0 0.0 ";
        String b = "0.0 0.0 0.0 0.0";
        String c = "[ 0.0, 0.0]";
        System.out.printf("%-20s %s\n", a, c);
        System.out.printf("%-20s %s\n", b, c);
    }
}

通过将上一个循环替换为以下内容，您可以在上述代码中使用此思想：

    // printing the array
    for(int row=0; row<figures.length; ++row) {
        // printing data row
        StringBuilder sb = new StringBuilder();

        group = (char)((row)+(int)'A');
        sb.append(group+" : ");
        for(int col=0; col<figures[row].length; ++col) {
            sum += figures[row][col];
            average = sum/figures[row].length;

            x = "   "+figures[row][col];
            diff = minLen - x.length();
            sb.append(String.format("%1$" + diff + "s", x));

            sb.append(" ");

        }
        System.out.printf("%-75s[%f]\n", sb.toString(), average);
    }

//打印数组
对于（int row=0；row，您需要找到列大小的最大数目，并在每行中迭代到max column，如果长度小于实际行长度，则放置该值，否则为空格。
它将解决这个问题

我添加了更改后的代码：

public class Array {

    // String result = String.format("The format method is           %s!", "great");
    //  System.out.println(result);
    //----------------------------------------------------------------
    private static Scanner Keyboard = new Scanner(System.in);

    public static void main(String[] args) {
        //----------------------------------------------------------------
        char group, rLetter, letter;
        String choice;
        String str = " ";
        double sum = 0;
        int num = 10; // for test
        int rows = 10;
        int columns = 8;
        double average = 0;
        int S;
        int diff = 0;
        int totalChar = 0;
        int minLen = 20;
        String x = "";

        // creating 2d array


        System.out.print("Please enter number of rows               : ");
        rows = Keyboard.nextInt();
        Keyboard.nextLine();


        double[][] figures = new double[rows][num];
        int maxSize = 0;
        for (int t = 0; t < rows; t++) {
            rLetter = (char) ((t) + 'A');
            System.out.print("Please enter number of positions in row " + rLetter + " : ");
            columns = Keyboard.nextInt();
            Keyboard.nextLine();
            if (columns > maxSize) {
                maxSize = columns;
            }
            figures[t] = new double[columns];
        }

        // filling the array
        for (int row = 0; row < figures.length; ++row) {
            for (int col = 0; col < figures[row].length; ++col) {
                figures[row][col] = 0.0;
            }
        }

        // printing the array
        for (int row = 0; row < figures.length; ++row) {
            // printing data row



            group = (char) ((row) + (int) 'A');
            System.out.print(group + " : ");
            for (int col = 0; col < maxSize; ++col) {
                if (col < figures[row].length) {
                    sum += figures[row][col];
                    average = sum / figures[row].length;

                    x = "   " + figures[row][col];
                    diff = minLen - x.length();
                    System.out.printf("%1$" + diff + "s", x);

                    System.out.print(" ");
                } else {
                    System.out.print("               ");
                }
            }

            System.out.print("[" + average + "]");
            System.out.println();


        }
    }
}

公共类数组{
//String result=String.format（“格式化方法是%s！”，“很棒”）；
//系统输出打印项次（结果）；
//----------------------------------------------------------------
专用静态扫描仪键盘=新扫描仪（System.in）；
公共静态void main（字符串[]args）{
//----------------------------------------------------------------
字符组，rLetter，字母；
字符串选择；
字符串str=“”；
双和=0；
int num=10；//用于测试
int行=10；
int列=8；
双平均=0；
int-S；
int-diff=0；
int totalChar=0；
int minLen=20；
字符串x=“”；
//创建二维阵列
System.out.print（“请输入行数：”）；
行=键盘.nextInt（）；
Keyboard.nextLine（）；
double[]数字=新的double[行][num]；
int maxSize=0；
for（int t=0；t最大大小）{
maxSize=列；
}
图[t]=新的双[列]；
}
//填充数组
对于（int row=0；row
所以在for循环中没有办法像我现在这样做吗？@user3505222，绝对有办法做到，但您没有提供一个完整的可编译程序，我可以尝试调试。此外，我假设您将使用
for
循环，而不考虑构建字符串的左半部分，也可能是右半部分。平均值为sho最多使用多个小数，否则原始问题就解决了。@user3505222，您可以通过将
%f
更改为
%.2f
来编辑小数数。
public class Array {

    // String result = String.format("The format method is           %s!", "great");
    //  System.out.println(result);
    //----------------------------------------------------------------
    private static Scanner Keyboard = new Scanner(System.in);

    public static void main(String[] args) {
        //----------------------------------------------------------------
        char group, rLetter, letter;
        String choice;
        String str = " ";
        double sum = 0;
        int num = 10; // for test
        int rows = 10;
        int columns = 8;
        double average = 0;
        int S;
        int diff = 0;
        int totalChar = 0;
        int minLen = 20;
        String x = "";

        // creating 2d array


        System.out.print("Please enter number of rows               : ");
        rows = Keyboard.nextInt();
        Keyboard.nextLine();


        double[][] figures = new double[rows][num];
        int maxSize = 0;
        for (int t = 0; t < rows; t++) {
            rLetter = (char) ((t) + 'A');
            System.out.print("Please enter number of positions in row " + rLetter + " : ");
            columns = Keyboard.nextInt();
            Keyboard.nextLine();
            if (columns > maxSize) {
                maxSize = columns;
            }
            figures[t] = new double[columns];
        }

        // filling the array
        for (int row = 0; row < figures.length; ++row) {
            for (int col = 0; col < figures[row].length; ++col) {
                figures[row][col] = 0.0;
            }
        }

        // printing the array
        for (int row = 0; row < figures.length; ++row) {
            // printing data row



            group = (char) ((row) + (int) 'A');
            System.out.print(group + " : ");
            for (int col = 0; col < maxSize; ++col) {
                if (col < figures[row].length) {
                    sum += figures[row][col];
                    average = sum / figures[row].length;

                    x = "   " + figures[row][col];
                    diff = minLen - x.length();
                    System.out.printf("%1$" + diff + "s", x);

                    System.out.print(" ");
                } else {
                    System.out.print("               ");
                }
            }

            System.out.print("[" + average + "]");
            System.out.println();


        }
    }
}