移除集合中null元素的几种方法

比眉伴天荒 2022-11-27 00:53 133阅读 0赞

**目录**

通过java

while循环

另外一个简单的方式

通过google guava框架

会修改原集合

保留原集合，新增新集合

通过Apache Commons

通java 8 lambada 表达式

--------------------

## 通过java ##

### while循环 ###

@Test
    public void removeNullFromList() {
        List<Integer> list = Lists.newArrayList(null, 1, null);
        while (list.remove(null));
     
        assertThat(list, hasSize(1));
    }

### 另外一个简单的方式 ###

@Test
    public void removeNullFromList() {
        List<Integer> list = Lists.newArrayList(null, 1, null);
        list.removeAll(Collections.singleton(null));
     
        assertThat(list, hasSize(1));
    }

## 通过google guava框架 ##

### 会修改原集合 ###

@Test
     public void removeNullFromList() {
         List<Integer> list = Lists.newArrayList(null, 1, null);
         Iterables.removeIf(list, Predicates.isNull());
    
         assertThat(list, hasSize(1));
      }

### 保留原集合，新增新集合 ###

@Test
    public void removeNullFromList() {
        List<Integer> list = Lists.newArrayList(null, 1, null, 2, 3);
        List<Integer> listWithoutNulls = Lists.newArrayList(
          Iterables.filter(list, Predicates.notNull()));
     
        assertThat(listWithoutNulls, hasSize(3));
    }

## 通过Apache Commons ##

@Test
     public void removeNullFromList() {
        List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
        CollectionUtils.filter(list, PredicateUtils.notNullPredicate());
    
        assertThat(list, hasSize(3));
     }

## 通java 8 lambada 表达式 ##

@Test
        public void removeNullFromListLambdaParallelStream() {
            List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
            List<Integer> listWithoutNulls = list.parallelStream()
                    .filter(Objects::nonNull)
                    .collect(Collectors.toList());
        }
    
        @Test
        public void removeNullFromListLambdaStream() {
            List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
            List<Integer> listWithoutNulls = list.stream()
                    .filter(Objects::nonNull)
                    .collect(Collectors.toList());
        }
    
        public void removeNullFromListLambdaRemoveIf() {
            List<Integer> listWithoutNulls = Lists.newArrayList(null, 1, 2, null, 3, null);
            listWithoutNulls.removeIf(Objects::isNull);
    
            assertThat(listWithoutNulls, hasSize(3));
        }

感觉哪种香就用哪种！