trebuchet

code snippets for some problems when handling java.lang.Throwables in using Stream API .

Getting Start

Add the following snippet to any project's pom that depends on your project

<repositories>
  ...
  <repository>
    <id>savage-reflections</id>
    <url>https://raw.github.com/furplag/trebuchet/mvn-repo/</url>
    <snapshots>
      <enabled>true</enabled>
      <updatePolicy>always</updatePolicy>
    </snapshots>
  </repository>
</repositories>
...
<dependencies>
  ...
  <dependency>
    <groupId>jp.furplag.sandbox</groupId>
    <artifactId>trebuchet</artifactId>
    <version>3.0.1-FINAL</version>
  </dependency>
</dependencies>

Usage

public static void main(String[] args) {
  // @formatter:off

  // [1, 2, 3, 4, 5, 6, 7, 8, 9]
  Integer[] vars = IntStream.rangeClosed(1, 9).boxed().toArray(Integer[]::new);
  System.out.println(Arrays.toString(vars));

  // [0, 0, 0, 0, 0, 0, 0, 0, 0]
  System.out.println(Arrays.toString(
    Arrays.stream(vars).map((x) -> (x - 1) / x).toArray(Integer[]::new)
  ));

  try {
    // java.lang.ArithmeticException: zero divide ...
    System.out.println(Arrays.toString(
      Arrays.stream(vars).map((x) -> x / (x - 1)).toArray(Integer[]::new)
    ));
  } catch (Exception e) {/* so, what we have to do next ? */}

  // we decided to try to against Exception, the code was ugliness .
  // [null, 2, 1, 1, 1, 1, 1, 1, 1]
  System.out.println(Arrays.toString(
    IntStream.rangeClosed(1, 9).boxed().map((x) -> {
      try {
        return x / (x - 1);
      } catch (Exception e) {/* so, what we have to do next ? */}

      return null;
    }).toArray(Integer[]::new)
  ));
  // @formatter:on

  // we have to do like that which checking vars every time in those many,  many of code ?
  System.out.println(Arrays.toString(
    Arrays.stream(vars).map((x) -> x == 1 ? null : (x / (x - 1))).toArray(Integer[]::new)
  ));

  // no, not need. That's it.
  System.out.println(Arrays.toString(
      Arrays.stream(vars).map(ThrowableFunction.of((x) -> x / (x - 1), (x, ex) -> null)).toArray(Integer[]::new)
  ));
  System.out.println(Arrays.toString(
      Arrays.stream(vars).map((t) -> ThrowableFunction.orElse(t, (x) -> x / (x - 1), (x, ex) -> null)).toArray(Integer[]::new)
  ));
  System.out.println(Arrays.toString(
      Arrays.stream(vars).map((i) -> ThrowableFunction.orNull(i, (x) -> x / (x - 1))).toArray(Integer[]::new)
  ));
}