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Improve ChainOfRespLambda #4

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27 changes: 13 additions & 14 deletions ...ain/java/org/mfusco/fromgoftolambda/examples/chainofresponsibility/ChainOfRespLambda.java
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Original file line number Diff line number Diff line change
Expand Up @@ -7,27 +7,27 @@
public class ChainOfRespLambda {

public static Optional<String> parseText(File file) {
return Optional.ofNullable(file)
.filter(f -> f.getType() == File.Type.TEXT )
.map(f -> "Text file: " + f.getContent());
return file.getType() == File.Type.TEXT ?
Optional.of("Text file: " + file.getContent()) :
Optional.empty();
}

public static Optional<String> parsePresentation(File file) {
return Optional.ofNullable(file)
.filter(f -> f.getType() == File.Type.PRESENTATION )
.map(f -> "Presentation file: " + f.getContent());
return file.getType() == File.Type.PRESENTATION ?
Optional.of("Presentation file: " + file.getContent()) :
Optional.empty();
}

public static Optional<String> parseAudio(File file) {
return Optional.ofNullable(file)
.filter(f -> f.getType() == File.Type.AUDIO )
.map(f -> "Audio file: " + f.getContent());
return file.getType() == File.Type.AUDIO ?
Optional.of("Audio file: " + file.getContent()) :
Optional.empty();
}

public static Optional<String> parseVideo(File file) {
return Optional.ofNullable(file)
.filter(f -> f.getType() == File.Type.VIDEO )
.map(f -> "Video file: " + f.getContent());
return file.getType() == File.Type.VIDEO ?
Optional.of("Video file: " + file.getContent()) :
Optional.empty();
}

public static void main( String[] args ) {
Expand All @@ -40,8 +40,7 @@ public static void main( String[] args ) {
ChainOfRespLambda::parseAudio,
ChainOfRespLambda::parseVideo )
.map(f -> f.apply( file ))
.filter( Optional::isPresent )
.map( Optional::get )
.flatMap(o -> o.map(Stream::of).orElseGet(Stream::empty)) // jdk9: Optional#stream()
.findFirst()
.orElseThrow( () -> new RuntimeException( "Unknown file: " + file ) )
);
Expand Down