Java Stream Filter Examples

Java Stream Filter Example.java

	/**
	 * filter() example of Java's Stream API 
	 * 
	 * 
	 * How to get certain items from a collection using the filter() 
	 * intermediate operation, and then show the result using the
	 * collect() terminal operation.
	 * 
	 * @author jonbonso
	 * @param args
	 */
	public static void main(String... args) {
		
		List<Integer> numList = new LinkedList<>();
		
		for (int i=1; i<= 10; i++) 
			numList.add(i);
		
		System.out.println(" numList size: " + numList.size() + "\n" + 
				" numList contents: " + numList);
		
		System.out.println("\n Using the old & verbose way of list iteration and if statement");
		
		List<Integer> oldWayNumList = numList;
		Iterator<Integer> itr = oldWayNumList.iterator();
		while(itr.hasNext()) {
			if( itr.next() <= 5) {
				itr.remove();
			}
		}
		
		System.out.println("\t numList contents: " + numList);
		System.out.println("\n Using the Java 8's Stream Filter");


		System.out.println("\t Filtering the List to only contains number greater than 5...");
		Stream<Integer> numStreamGreaterThan5 = 
				numList.stream()
				.filter( 
					// Use the lambda expression (->) and 
				    // supply the filter condition, which is the num 
					// should be greater to 5.
					n -> (n > 5) 
				);
		
		System.out.println("\t numStream contents: " + 
				numStreamGreaterThan5.collect(Collectors.toList()) );
		
	}