和值类的对象属性在的ArrayList [英] Sum value Of Class Objects Property In ArrayList

问题描述

我有一个具有多个对象的ArrayList。我想这样做相同的属性名称的值的总和。

I have an ArrayList which having many objects. I want to do sum of values of the same property name.

例子数组列表这是<强> ProfitAndLossDataDO

      "Michel" , 5000
      "Alex" , 5000
      "Edvin" , 4000
      "Sosha" , 3000
      "Michel" , 2000
      "Alex" , 3000

和结果将是（值的总和，当人相同） -

And the Result Would be (Sum of values when person are same)-

      "Michel" ,7000
      "Alex" ,  8000
      "Edvin" , 4000
      "Sosha" , 3000

逻辑类的 ProfitAndLossDataDO

public class ProfitAndLossDataDO {

String ledgerName;
double ledgerAmount;

public ProfitAndLossDataDO() {
}

public ProfitAndLossDataDO(String ledgerName, double ledgerAmount) {
    this.ledgerName = ledgerName;
    this.ledgerAmount = ledgerAmount;
}



public String getLedgerName() {
    return ledgerName;
}

public void setLedgerName(String ledgerName) {
    this.ledgerName = ledgerName;
}

public double getLedgerAmount() {
    return ledgerAmount;
}

public void setLedgerAmount(double ledgerAmount) {
    this.ledgerAmount = ledgerAmount;
}


@Override
public String toString()
{
            return ("ledger name : "+this.getLedgerName()+" Amount : "+this.getLedgerAmount());
}
}

感谢

推荐答案

我迭代列表和地图收集结果：

I'd iterate the list and collect the results in a map:

public static List<ProfitAndLossDataDO> sumPerLedgerName
    (List<ProfitAndLossDataDO> list) {

    Map<String, ProfitAndLossDataDO> map = new HashMap<>();

    for (ProfitAndLossDataDO p : list) {
        String name = p.getLedgerName();
        ProfitAndLossDataDO sum = map.get(name);
        if (sum == null) {
            sum = new ProfitAndLossDataDO(name, 0.0);
            map.put(name, sum);
        }
        sum.setLedgerAmount(sum.getLedgerAmount() + p.getLedgerAmount());
    }
    return new ArrayList<ProfitAndLossDataDO>(map.values());
}

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