java – 通过从Scanner读取行来实例化ArrayList,在哪里声明对象

发布时间：2020-12-15 04:40:36 所属栏目：Java 来源：网络整理

导读：我想用输入文件中的行填充数组列表,输入文件如下所示： 7f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000

我想用输入文件中的行填充数组列表,输入文件如下所示：

7f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000020101
7f00000000000000000000000000000000000000000000000000000000000000037f00000000000000000000000000000000000000000000000000000000000000037f00000000000000000000000000000000000000000000000000000000000000030101
7f00000000000000000000000000000000000000000000000000000000000000047f00000000000000000000000000000000000000000000000000000000000000047f00000000000000000000000000000000000000000000000000000000000000040101
7f00000000000000000000000000000000000000000000000000000000000000057f00000000000000000000000000000000000000000000000000000000000000057f00000000000000000000000000000000000000000000000000000000000000050101
7f00000000000000000000000000000000000000000000000000000000000000067f00000000000000000000000000000000000000000000000000000000000000067f00000000000000000000000000000000000000000000000000000000000000060101

我想基于此创建的Java中的数据对象将这些行中的每一行作为新字符串,并且它们将一起存在于列表中,可以这么说*.

因此,在我尝试将文件行读入此数组列表的不同组件时,我无法弄清楚我需要在主程序中声明数组列表的位置.我的计划是用一个单独的方法填充它：

import java.io.*;
import java.util.Scanner;
import java.util.List;
import java.util.Array;
import java.util.ArrayList;

class evmTest {

public static void main(String[] args) {


    Array<String> inputLinesObject = new ArrayList<String>();

    // populate from file
    inputLinesObject = readFile("/Users/s.matthew.english/codes.txt",inputLinesObject);


    System.out.println(Array.toString(inputLinesObject));

}

    private static void readFile(String fileName,Array<String> inputLines) {
        try {
            File file = new File(fileName);
            Scanner scanner = new Scanner(file);
            while (scanner.hasNextLine()) {
                // System.out.println(scanner.nextLine());
                inputLines.add(scanner.nextLine());
            }
            scanner.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        return inputLines;
    }

}

也许我最初可以将它实例化为null,然后将该空数组列表传递给要填充的方法？

*最后一句话中的术语并不完全准确 – 请原谅我 – 我正在重新调整Java的词汇量,但我认为它应该足够清楚我正在尝试做什么.如果没有,请告诉我,我将很乐意澄清.

解决方法

将此代码用于readFile()方法：

private static List<String> readFile(String fileName,List<String> inputLines) {
    try {
        File file = new File(fileName);
        Scanner scanner = new Scanner(file);
        while (scanner.hasNextLine()) {
            // System.out.println(scanner.nextLine());
            inputLines.add(scanner.nextLine());
        }
        scanner.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    return inputLines;
}

然后调用此readFile()方法如下：

List<String> inputLinesObject = new ArrayList<String>();
inputLinesObject = readFile("/Users/s.matthew.english/codes.txt",inputLinesObject);

for(String str : inputLinesObject){
     System.out.println(str);
}

（编辑：李大同）

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