12. Exceptions

12.1. Divide by zero example

var a = 10;
var b = 0;
var c = a / b;

12.2. try-catch

var a = 10;
var b = 0;

try {
  var c = a / b;
  System.out.println(a + " / " + b + " = " + c);
} catch (ArithmeticException e) {
  System.out.println(a + " / " + b + " => " + e);
}

12.3. throw

var a = 10;
var b = 0;

try {
  var c = a / b;
  System.out.println(a + " / " + b + " = " + c);
} catch (ArithmeticException e) {
  throw new ArithmeticException(a + " / " + b + " => " + e);
}

12.4. try-catch-finally

var a = 10;
var b = 0;
var c = -1;

try {
  c = a / b;
} catch (ArithmeticException e) {
  // swallow
} finally {
  if (c == -1) {
    System.err.println(a + " / " + b + " cannot be computed");
  }
}

12.5. try-catch with resources

import com.opencsv.CSVParserBuilder;
import com.opencsv.CSVReaderBuilder;
import com.opencsv.CSVWriterBuilder;
import com.opencsv.ICSVParser;
import com.opencsv.ICSVWriter;
import java.io.FileReader;
import java.io.FileWriter;

try (var writer = new CSVWriterBuilder(new FileWriter("demo.csv"))
    .withSeparator(ICSVParser.DEFAULT_SEPARATOR)
    .withQuoteChar(ICSVParser.DEFAULT_QUOTE_CHARACTER)
    .withEscapeChar(ICSVParser.DEFAULT_ESCAPE_CHARACTER)
    .withLineEnd(ICSVWriter.DEFAULT_LINE_END)
    .build()) {

  var entries = new String[][] {
      { "first_name", "last_name" },
      { "John", "Doe" },
      { "Jane", "Smith" }
  };

  for (String[] row : entries) {
    writer.writeNext(row);
  }
}

final var parser = new CSVParserBuilder()
    .withSeparator(ICSVParser.DEFAULT_SEPARATOR)
    .withQuoteChar(ICSVParser.DEFAULT_QUOTE_CHARACTER)
    .withEscapeChar(ICSVParser.DEFAULT_ESCAPE_CHARACTER)
    .build();

try (var reader = new CSVReaderBuilder(new FileReader("demo.csv"))
    .withSkipLines(1)
    .withCSVParser(parser)
    .build()) {
  String[] line;
  while ((line = reader.readNext()) != null) {
    for (int i = 0; i < line.length; i++) {
      System.out.print(line[i]);
      if (i < line.length - 1) {
        System.out.print(", ");
      } else if (i == line.length - 1) {
        System.out.println();
      }
    }
  }
}