My first experience with lambda expressions in java

My first experience with lambda expressions in java

• 1.
  My First Experiencewith Lambda Expressions in Java 8 Tibor Digana
• 2.
  What do Ineed ? • First of all download and install OpenJDK 1.8 http://jdk8.java.net/lambda/ • Write and compile the following simple code
• 3.
  Threads and For-Eachin Lambda
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  Overriding run method •Runnable#run() is anonymous function • New Thread instance is created • New Runnable instance is passed to the constructor of Thread • run() method calls connectToService()
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  forEach on Collection • Anonymous function with one parameter • for-each iterates over given List • Takes elements and computes their sum • The sum variable must be final or static
• 6.
  Map-Reduce List<Integer> list =Arrays.asList(1, 2, 3); int x = list.stream().map(e -> e).reduce(0, (a, b) -> a + b); • Mapping values of elements 1:1 • Splitting the collection to two parties • Splitting parties again, etc. • Computing the SUM on each party • Reducing their sub-results in the final result
• 7.
  Anonymous Function without parameters is Runnable Object run(Runnable... blocks) {…} …… run( () -> { System.out.println("first..."); }, () -> { System.out.println("second..."); } ); • Passing functionality/task to a thread pool • Simple when assigning Runnable r = () -> {…}; • Simply registering a listener #addListener( ()-> {…} ) • No need to write anonymous class with one method
• 8.
  References • http://stackoverflow.com/questions/10332402/cant-get-lambdas-to-compile-in-netbeans-7-1-1jdk8-jdk-8-ea-bin-b35 • http://jdk8.java.net/lambda/ • http://www.javabeat.net/2012/05/enhanced-collections-api-in-java-8-supports-lambda-expressions/ • http://cr.openjdk.java.net/~briangoetz/lambda/lambda-state-4.html