Java8--Lambda expression on List collection operation (1)

1. Use stream().forEach() to traverse the collection

			List<String> list = new ArrayList<String>();
			list.add("djk");
			list.add("djk1");
			list.add("djk12");
			list.add("djk123");	
			//利用stream().forEach()遍历集合
			list.stream().forEach(item->{System.out.print(item+" ");});

2. Use stream().map() to capitalize the List, assign a value to another List, and traverse it

		List<String> list = new ArrayList<String>();
			list.add("djk");
			list.add("djk1");
			list.add("djk12");
			list.add("djk123");
			List<String> list4 = new ArrayList<String>();
			list4 = list.stream().map(item->item.toUpperCase()).collect(Collectors.toList());
			list4.stream().forEach(item->{System.out.println(item);});

3. Use stream().filter() to filter the List, assign a value to another list, and traverse it

			List<String> list = new ArrayList<String>();
			list.add("djk");
			list.add("djk1");
			list.add("djk12");
			list.add("djk123");		
			List<String> list3 = new ArrayList<String>();			
			list3 = list.stream().filter(item->!item.equals("djk")).collect(Collectors.toList());
			list3.stream().forEach(item->{System.out.println(item);});

Four, find the maximum, minimum, sum, average, and number of elements in a sequence

			List<Integer> listint = new ArrayList<Integer>();
			listint.add(1);
			listint.add(2);
			listint.add(3);
			listint.add(4);
			listint.add(5);
			IntSummaryStatistics stat = listint.stream().mapToInt((item)->item).summaryStatistics();
			System.out.println("max:"+stat.getMax());
			System.out.println("min:"+stat.getMin());
			System.out.println("sum:"+stat.getSum());
			System.out.println("count:"+stat.getCount());
			System.out.println("average:"+stat.getAverage());

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