Java 双指针项目中的实际应用

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背景说明

最近在做财务相关的系统，对账单核销预付款从技术角度来看就是将两个数组进行合并

对账单核销预付款前提条件：

1. 对账单总金额必须等于未核销金额

数据示例

对账单数据

预付款数据

结果数据

通过分析可以使用JAVA双指针算法可以实现这个需求双指针主要用于遍历数组，两个指针指向不同的元素，从而协同完成任务。

代码实现

public static void main(String[] args) {    class Info {        private String formId;        private BigDecimal amount;            public String getFormId() {            return formId;        }            public void setFormId(String formId) {            this.formId = formId;        }            public BigDecimal getAmount() {            return amount;        }            public void setAmount(BigDecimal amount) {            this.amount = amount;        }    }        List billBatchlist = new ArrayList<>();    Info info = new Info();    info.setFormId("B0001");    info.setAmount(new BigDecimal(100));    billBatchlist.add(info);    info = new Info();    info.setFormId("B0002");    info.setAmount(new BigDecimal(80));    billBatchlist.add(info);    info = new Info();    info.setFormId("B0003");    info.setAmount(new BigDecimal(120));    billBatchlist.add(info);        List payVerifyControlList = new ArrayList<>();    Info info1 = new Info();    info1.setFormId("PRE0001");    info1.setAmount(new BigDecimal(110));    payVerifyControlList.add(info1);    info1 = new Info();    info1.setFormId("PRE0002");    info1.setAmount(new BigDecimal(190));    payVerifyControlList.add(info1);    billBatchlist.forEach(a -> {        System.out.println("BillFormId:" + a.formId + ",Amount:" + a.getAmount());    });    payVerifyControlList.forEach(a -> {        System.out.println("PreFormId:" + a.formId + ",Amount:" + a.getAmount());    });    System.out.println("==================================");        int i = 0, j = 0;    BigDecimal preAmount = new BigDecimal(0);    BigDecimal billAmount = new BigDecimal(0);    while (i < billBatchlist.size() && j < payVerifyControlList.size()) {        if (preAmount.compareTo(BigDecimal.ZERO) == 0) {            preAmount = billBatchlist.get(i).amount;        }        if (billAmount.compareTo(BigDecimal.ZERO) == 0) {            billAmount = payVerifyControlList.get(j).amount;        }            //当前核销金额        BigDecimal verifyAmount = new BigDecimal(0);        if (preAmount.compareTo(billAmount) > -1) {            verifyAmount = billAmount;            // pre剩余            preAmount = preAmount.subtract(verifyAmount);            billAmount = new BigDecimal(0);        } else {            verifyAmount = preAmount;            // bill剩余            billAmount = billAmount.subtract(verifyAmount);            preAmount = new BigDecimal(0);        }            System.out.println("当前核销金额：" + verifyAmount + ",preAmount剩余:" + preAmount + ",billAmount剩余:" + billAmount);        //大于等于0        if (preAmount.compareTo(BigDecimal.ZERO) == 0) {            i++;        }        if (billAmount.compareTo(BigDecimal.ZERO) == 0) {            j++;        }    }    }

打印结果：

BillFormId:B0001,Amount:100BillFormId:B0002,Amount:80BillFormId:B0003,Amount:120PreFormId:PRE0001,Amount:110PreFormId:PRE0002,Amount:190==================================当前核销金额：100,preAmount剩余:0,billAmount剩余:10当前核销金额：10,preAmount剩余:70,billAmount剩余:0当前核销金额：70,preAmount剩余:0,billAmount剩余:120当前核销金额：120,preAmount剩余:0,billAmount剩余:0