我有兩個列表List<AreaOfInterest>和List<AreaOfInterestBean>. 對應(yīng)的類是，@Entity@Data@Table( name = "interest_area" )public class AreaOfInterest { @Id @GeneratedValue( strategy = GenerationType.AUTO ) @Column( name = "ia_id" ) private Long id; @Column( name = "ia_value" ) private String value; @Column( name = "ia_is_active" ) private Boolean isActive; @Column( name = "ia_created_at" ) private Calendar createdAt; @Column( name = "ia_is_approved" ) private Boolean isApprovedByAdmin; @Column( name = "ia_approved_at" ) private Calendar approvedAt;}和，@Datapublic class AreaOfInterestBean { private Long id; private String value; private boolean isSelected;}我想檢查 的對象List<AreaOfInterest>是否存在List<AreaOfInterestBean>，如果存在，我需要更新List<AreaOfInterestBean>. 現(xiàn)在，我覺得我必須迭代兩個列表來解決這個問題。有什么有效的方法嗎？
2 回答
動漫人物
TA貢獻1815條經(jīng)驗 獲得超10個贊
老實說，我不確定這的復(fù)雜性（我明天會嘗試弄清楚）：
Set<String> left = nonBeans.stream()
.map(AreaOfInterest::getValue)
.collect(Collectors.toSet());
beans.stream()
.filter(x -> left.contains(x.getValue()))
.forEach(x -> x.setSelected(true));
在這種情況下，復(fù)雜性將為O(n).
ibeautiful
TA貢獻1993條經(jīng)驗 獲得超6個贊
假設(shè)：
List<AreaOfInterest> list = /* ... */
List<AreaOfInterestBean> listOfBeans = /* ... */
兩個簡單的迭代可以輕松實現(xiàn)：
for (int i=0; i<listOfBeans.size(); i++) { // Iterate beans
AreaOfInterestBean aoiBean = listOfBeans.get(i); // Get each bean
for (int j=0; j<list.size(); j++) { // Iterate entity
AreaOfInterest aoi = list.get(j); // Get each entity
if (aoiBean.getId() == aoi.getId()) { // If they have the same ID
aoiBean.setValue(aoi.getValue()); // Update the bean value
break; // Go to the next bean
}
}
}
示例：具有以下簡化數(shù)據(jù)：
AreaOfInterest同id和value：1, "Car"，2, "Bike"，3, "Ship"
AreaOfInterestBeans同id和value：5, "Limo"，2, "Scooter"，7, "Yacht"
結(jié)果AreaOfInterestBeans將是 id 的替換值2：Scooter-> Bike。
AreaOfInterestBeans同id和value：5, "Limo"，2, "Bike"，7, "Yacht"
另一種流方式：
listOfBeans = listOfBeans.stream()
.peek(aoiBean -> list.stream()
.filter(aoi -> aoi.getId() == aoiBean.getId())
.findFirst()
.ifPresent(i -> aoiBean.setValue(i.getValue())))
.collect(Collectors.toList());
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