【工具方法】List拆分

痛定思痛。 2022-04-11 10:20 294阅读 0赞

#### 将源List按照指定元素数量拆分为多个List ####

**废话不多说，直接上代码**

/** * 将源List按照指定元素数量拆分为多个List * * @param source 源List * @param splitItemNum 每个List中元素数量 */
        public static <T> List<List<T>> averageAssign( List<T> source, int splitItemNum )
        { 
            List<List<T>> result = new ArrayList<List<T>>();
    
            if ( source != null && source.size() > 0 && splitItemNum > 0 ){ 
                if ( source.size() <= splitItemNum ){ 
                    // 源List元素数量小于等于目标分组数量
                    result.add( source );
                }else{ 
                    // 计算拆分后list数量
                    int splitNum = ( source.size() % splitItemNum == 0 ) ? ( source.size() / splitItemNum ) : ( source.size() / splitItemNum + 1 );
    
                    List<T> value = null;
                    for ( int i = 0; i < splitNum; i++ ){ 
                        if ( i < splitNum - 1 ){ 
                            value = source.subList( i * splitItemNum, ( i + 1 ) * splitItemNum );
                        }else{ 
                            // 最后一组
                            value = source.subList( i * splitItemNum, source.size() );
                        }
    
                        result.add( value );
                    }
                }
            }
    
            return result;
        }

**测试代码**

public static void main( String[] args )
        { 
            List<Integer> source = new ArrayList<Integer>();
    
            for ( int i = 1; i <= 101; i++ ){ 
                source.add( i );
            }
    
            List<List<Integer>> result = averageAssign( source, 10 );
    
            for ( List<Integer> re : result ){ 
                System.out.println( JSON.toJSONString( re ) );
            }
    
        }

**运行结果**

[1,2,3,4,5,6,7,8,9,10]
    [11,12,13,14,15,16,17,18,19,20]
    [21,22,23,24,25,26,27,28,29,30]
    [31,32,33,34,35,36,37,38,39,40]
    [41,42,43,44,45,46,47,48,49,50]
    [51,52,53,54,55,56,57,58,59,60]
    [61,62,63,64,65,66,67,68,69,70]
    [71,72,73,74,75,76,77,78,79,80]
    [81,82,83,84,85,86,87,88,89,90]
    [91,92,93,94,95,96,97,98,99,100]
    [101]