Java/サンプル集の履歴(No.4)

CSVを読み込む†

data.csv

1A,1B,1C
2A,2B,2C
3A,3B,3C
4A,4B,4C
5A,5B,5C

CSVReader.java

import java.io.*;
import java.util.StringTokenizer;

public class CSVReader {
    
    public static void main(String args[]) throws Exception {
        
        String fileName = "data.csv";
        
        BufferedReader reader = new BufferedReader(new FileReader(fileName));
        
        String lineText = null;
        while ((lineText = reader.readLine()) != null) {
            
            StringTokenizer tokenizer = new StringTokenizer(lineText, ",");
            
            while (tokenizer.hasMoreTokens()) {
                System.out.print(tokenizer.nextToken());
                if (tokenizer.hasMoreTokens()) System.out.print(":");
            }
            
            System.out.println();
        }
        
        reader.close();
        
    }
    
}

↑

CSVを書きこむ†

CSVWriter.java

import java.io.*;

public class CSVWriter {
    
    public static void main(String args[]) throws Exception {
        
        String fileName = "data.csv";
        
        BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
        
        writer.write("1D,1E,1F");
        writer.newLine();
        
        writer.write("2D,2E,2F");
        writer.newLine();
        
        writer.write("3D,3E,3F");
        writer.newLine();
        
        writer.write("4D,4E,4F");
        writer.newLine();
        
        writer.write("5D,5E,5F");
        writer.newLine();
        
        writer.close();
    }
    
}

↑

XMLを読み込む†

data.xml

<?xml version="1.0" encoding="UTF-8"?>
<root><要素>値</要素></root>

XMLReader.java

import org.w3c.dom.*;
import javax.xml.parsers.*;


public class XMLReader {
    
    public static void main(String args[]) throws Exception {
        
        String fileName = "data.xml";
        
        Document xmlDoc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(fileName);
        System.out.println(xmlDoc.getElementsByTagName("要素").item(0).getFirstChild().getNodeValue());
        
    }
    
}

↑

ファイル名から拡張子を除いたベース名を取得する†

FileNameWithoutExtension.java

public class FileNameWithoutExtension {
    
    public static void main(String args[]) throws Exception {
        System.out.printf("%s:[%s]\r\n", "sample.dat", getFileNameWithoutExtension("sample.dat"));
        System.out.printf("%s:[%s]\r\n", ".dat", getFileNameWithoutExtension(".dat"));
        System.out.printf("%s:[%s]\r\n", "sample_dat", getFileNameWithoutExtension("sample_dat"));
    }
    
    
    private static String getFileNameWithoutExtension(String fileName) {
        
        int startExtensionIndex = fileName.lastIndexOf('.');
        
        if (startExtensionIndex < 0) return fileName;
        if (startExtensionIndex == 0) return "";
        
        return fileName.substring(0, startExtensionIndex);
    }
    
}

Java/サンプル集 の履歴(No.4)

CSVを読み込む†

CSVを書きこむ†

XMLを読み込む†

ファイル名から拡張子を除いたベース名を取得する†