Bearbeiten von „Das Beispiel CvsTool:Javakurs“

[[Category:Tutorial]]
[[Category:Java]]

<pre><code>
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class CsvTool {
    String lines[] = null;
    String name;
    String separator = ";";
    public String[] readFile(final String filename) throws IOException {
        final int count = countLines(filename);
        final String lines[] = new String[count];
        final File file = new File(filename);
        final BufferedReader reader = new BufferedReader(new FileReader(file));
        String line;
        int ix = 0;
        while (ix < count && (line = reader.readLine()) != null)
            lines[ix++] = line;
        reader.close();
        return lines;
    }
    public void writeFile(final String filename) throws IOException {
        final BufferedWriter writer = new BufferedWriter(new FileWriter(
            new File(filename)));
        for (int ix = 0; ix < this.lines.length; ix++)
            writer.write(this.lines[ix] + "\n");
        writer.close();
    }
    public int countLines(final String filename) throws IOException {
        int count = 0;
        final File file = new File(filename);
        final BufferedReader reader = new BufferedReader(new FileReader(file));
        while (reader.readLine() != null)
            count++;
        reader.close();
        return count;
    }
    public String getCol(final int lineNo, final int col) {
        String rc = null;
        if (lineNo >= 0 && lineNo < this.lines.length) {
            final String line = this.lines[lineNo];
            final String[] cols = line.split(this.separator);
            if (col >= 0 && col < cols.length)
                rc = cols[col];
        }
        return rc;
    }
    public void setCol(final int lineNo, final int col, final String value) {
        if (col >= 0 && lineNo >= 0 && lineNo < this.lines.length) {
            String line = this.lines[lineNo];
            final int count = countCols(line);
            if (count < col){
                final String[] cols = line.split(line);
                cols[col] = value;
                this.lines[lineNo] = join(cols);
            } else {
                for (int ix = count; ix < col; ix++)
                    line = line + this.separator;
                this.lines[lineNo] = line + value;
            }
        }
    }
    public int countCols(final String line) {
        int rc = 0;
        int ix = 0;
        while ((ix = line.indexOf(this.separator, ix)) > 0)
            rc++;
        return rc;
    }
    public String join(final String[] cols) {
        final StringBuilder buffer = new StringBuilder();
        for (int ix = 0; ix < cols.length; ix++) {
            if (ix > 0)
                buffer.append(this.separator);
            buffer.append(cols[ix]);
        }
        return buffer.toString();
    }
    public static void main(final String[] args) {
        String fname = "test.csv";
        if (args.length > 0)
            fname = args[0];
        final CsvTool tool = new CsvTool();
        try {
            tool.readFile(fname);
        } catch (final IOException e) {
            e.printStackTrace();
        }
    }
}
</code></pre>