java循环数组列表的批处理

Question

我想在小批量中迭代ArrayList

例如，如果ArrayList大小为75，批处理大小为10，我希望它处理记录0-10，然后10-20，然后20-30，等等

我试过这个，但不起作用：

int batchSize = 10;
int start = 0;
int end = batchSize;

for(int counter = start ; counter < end ; counter ++)
{
    if (start > list.size())
    {
        System.out.println("breaking");
        break;
    }

    System.out.println("counter   " + counter);
    start = start + batchSize;
    end = end + batchSize;
}

Answer 1

您需要的是：Lists.partition(java.util.List, int)来自Google Guava

例如：

final List<String> listToBatch = new ArrayList<>();
final List<List<String>> batch = Lists.partition(listToBatch, 10);
for (List<String> list : batch) {
  // Add your code here
}

Answer 2

int start = 0;
int end=updateBatchSize;
List finalList = null;
 try {
        while(end < sampleList.size()){
            if(end==sampleList.size()){
                break;
            }
            finalList = sampleList.subList(Math.max(0,start),Math.min(sampleList.size(),end));
            start=Math.max(0,start+updateBatchSize);
            end=Math.min(sampleList.size(),end+updateBatchSize);
        }

Answer 3

您可以像从批次大小和列表大小中提取余数一样查找计数

int batchSize = 10;
int start = 0;
int end = batchSize;

int count = list.size() / batchSize;
int remainder = list.size() % batchSize;
int counter = 0;
for(int i = 0 ; i < count ; i ++)
{
    System.out.println("counter   " + counter);
    for(int counter = start ; counter < end ; counter ++)
    {
        //access array as a[counter]
    }
    start = start + batchSize;
    end = end + batchSize;
}

if(remainder != 0)
{
    end = end - batchSize + remainder;
    for(int counter = start ; counter < end ; counter ++)
    {
       //access array as a[counter]
    }
}