docs: update docs/java.md. (#601)

docs/java.md

@@ -1038,6 +1038,40 @@ Map<Integer, Long> frequencyMap = list.stream().collect(Collectors.groupingBy(x
 // 3: 1
 ```
 
+`Stream`是`JAVA 8`添加的新特性，类似于一种管道。
+
+```java
+// Create the stream
+List<String> test = Arrays.asList("123", "456", "789");
+Stream<String> stram = test.stream();
+// some intermediate operations
+
+// fillter
+// The original operation
+List<TestDO> resultList = new ArrayList<>();
+for(TestDO test: testList){
+  if(test.getTest().equals(Boolean.TRUE){
+    resultList.add(test);
+  }
+}
+// The stream operation
+List<TestDO> resultList = testList.stream().fillter(test -> test.getTest().equals(Boolean.TRUE)).collect(Collectors.toList());
+
+//distinct
+List<String> test = Arrays.asList("123", "456", "789", "123");
+test.stream().distinct().forEach(System.out::println);
+
+//map
+List<String> test = Arrays.asList("123", "456", "789", "123");
+test.stream().map(i -> i + "hh").forEach(System.out::println);
+
+// sorted
+List<Integer> numbers = Arrays.asList(3, 2, 1);
+numbers.stream().sorted().forEach(System.out::println);
+
+
+```
+
 另见
 ---