如何使用 Printwriter 将字符串数组写入 java 中的文本文件？

Question

我需要帮助使用 Printwriter 将数组对象的一些内容（以下是我正在使用的两个数组示例）写入文本文件。有任何想法吗？我是初学者，所以越简单越好，谢谢！

Astronauts[0][0] = new Passengers(-1, "", 1, 0, 0, "", "", 0, "", "", "", "", ""); 

Astronauts[0][1] = new Passengers(0, "Pilot", 2424, 14, 0, "Bruce", "Banner", 0, "678-884-6325", "Mom", "678-884-6323","","");

Astronauts[0][2] = new Passengers(0, "Pilot", 1248, 3, 0, "Sally", "Forth", 0, "678-921-1135", "Hannah", "678-921-1130","","");


 Astronauts[1][0] = new Passengers(-1, "", 2, 0, 0, "", "", 0, "", "", "", "", "");

Astronauts[1][1] = new Passengers(0, "Pilot", 1022, 55, 0, "Buz", "Aldrin", 0, "404-014-4553", "June", "404-014-4555","","");

Astronauts[1][2] = new Passengers(0, "Pilot", 2813, 8, 0, "Alice", "Dyer", 0, "678-884-6325", "Mom", "678-884-6323","","");

Answer 1

我不确定我是否正确地抓住了你的问题，因为将数组的内容写入文件非常简单：

String[] arr = {"a", "b", "c"};
try {
    PrintWriter pw = new PrintWriter(new FileWriter("output.txt"));
    pw.println(Arrays.toString(arr));
    pw.flush();
    System.out.println("Finished");
} catch (IOException e) {
    e.printStackTrace();
}

[编辑]

我意识到我可能没有解决您的全部问题。如果您想知道如何编写包含在数组中的对象的所需特征，您可以覆盖自定义 class:[=13 的 toString() 方法=]

class A {
    public static void main(String[] args) {
        B[] bs = {new B("a", "b"),
                  new B("c", "d"),
                  new B("e", "f"),
                  new B("g", "h")};

        try {
            PrintWriter pw = new PrintWriter(new FileWriter("output.txt"));
            for (B b : bs) {
                pw.println(b);
            }
            pw.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("Finished");
    }
}

class B {
    private String prop1;
    private String prop2;

    public B (String prop1, String prop2) {
        this.prop1 = prop1;
        this.prop2 = prop2;
    }

    @Override
    public String toString() {
        return this.prop1 + " " + this.prop2;
    }
}

Answer 2

PrintWriter承认String，所以你可以覆盖Astronautsclass中的toString()方法，然后遍历一维或二维D维数组：

顺便说一下，变量名应该以小写字符开头。

一维

for (int i = 0; i < astronauts.length; i++) { 
    pw.print(Arrays.toString(astronauts[i]); 
}

二维

for (int i = 0; i < astronauts.length; i++) {
    for (int j = 0; j < astronauts[i].length; i++) {
        pw.print(astronauts[i][j]); 
    } 
}

别忘了 flush() 和 close() PrintWriter

Answer 3

以下是您可能想要的方法。

String twoDArray[][] = {{"one","two"},{"one","two"},{"one","two"}};
    String filePath = "C:/Users/arjun.lajpal/Desktop/dummyFile.txt";
    PrintWriter writer = null;
    try {
        writer = new PrintWriter(filePath);
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    writer.printf("%20s%20s","Astraunauts","Passengers");
    writer.println();
    for(int i=0;i<twoDArray.length;i++){
        for(int j=0;j<twoDArray[i].length;j++)
            writer.printf("%20s",twoDArray[i][j]);

        writer.println();

        }
    writer.flush();
    writer.close();

这不仅会生成您的文件，而且会以漂亮的表格格式写入文件，而无需重写 toString() 方法。

Answer 4

由于您的数组内容都是相同的 class Passengers，如果您对默认的 Array.toString 格式不满意，我会创建一个 toString() Passengers 中的方法 returns 您想要的字符串表示形式。

然后：

try {
       PrintWriter printWriter = new PrintWriter(new FileWriter("output.txt"));

       for(Passengers[] passengers: Astronauts) {
           for(Passengers passenger: passengers) {
                printWriter.println(passenger);
           }
       }

       printWriter.close();  // no need to flush, since close() does it anyway.

   } catch (IOException e) {
       e.printStackTrace();
   }

注意：正如其他人所提到的，我将 Astronauts 变量重命名为小写 astronauts。我还将 Passengers class 重命名为 Passenger.

编辑：使用上面的代码，输出文件应该出现在您运行程序所在的工作目录中。或者，您可以提供完整的文件路径，例如 C:/Users/Me/directory/output.txt，但在这种情况下，您需要确保目录路径已经存在。

另一种方法是修改代码以自动为您创建路径：

    File file = new File ("C:/Users/Me/directory/output.txt");
    file.getParentFile().mkdirs();
    PrintWriter printWriter = new PrintWriter(file);

如何使用 Printwriter 将字符串数组写入 java 中的文本文件？

How do I write String arrays to a text file in java using Printwriter?

java

arrays

string

text

file