英文:
How can i reduce this repeat code in Java 8?
问题
我有以下的代码，它一直重复很多次。也许有一种方法可以减少它，但我不太了解Java。它看起来像这样：
public Optional<byte[]> generateReportA(List<ClassThatChange> request){
if(CollectionUtils.isEmpty(request)) {
return Optional.empty();
}
List<ClassThatNOChange> list = new ArrayList<>();
for(ClassThatChange item : request){
ClassThatNOChange c = new ClassThatNOChange()
//这是从一个报告到另一个报告会改变的代码行
c.setResult(callMethodA(item.getVariable1(), item.getVariable2()));
list.add(c);
}
return Optional.of(callSameMethod(list));
}
public Optional<byte[]> generateReportB(List<ClassThatChange> request){
if(CollectionUtils.isEmpty(request)) {
return Optional.empty();
}
List<ClassThatNOChange> list = new ArrayList<>();
for(ClassThatChange item : request){
ClassThatNOChange c = new ClassThatNOChange()
//这是从一个报告到另一个报告会改变的代码行
c.setResult(callMethodB(item.getVariable2()));
list.add(c);
}
return Optional.of(callSameMethod(list));
}
唯一会改变的是callMethodA、callMethodB等，但它们都返回相同类型的答案。
ClassThatChange 类似于这样：
public class Father{
private Date date;
// 然后是 getters 和 setters
}
public class Son extends Father{
private String description;
// 然后是 getters 和 setters
}
所有可以改变的类都扩展自Father。
有没有一种方法可以减少这种重复的代码？
对不起，我的英语不太好。
英文:
I have the following code that keeps repeating a lot. Maybe there is a way to reduce it but i dont know too much of java. It looks like this:
public Optional<byte[]> generateReportA(List<ClassThatChange> request){
if(CollectionUtils.isEmpty(request)) {
return Optional.empty();
}
List<ClassThatNOChange> list = new ArrayList<>();
for(ClassThatChange item : request){
ClassThatNOChange c = new ClassThatNOChange()
//here is the line of code that changes from report to report
c.setResult(callMethodA(item.getVariable1(), item.getVariable2()));
list.add(c);
}
return Optional.of(callSameMethod(list));
}
public Optional<byte[]> generateReportB(List<ClassThatChange> request){
if(CollectionUtils.isEmpty(request)) {
return Optional.empty();
}
List<ClassThatNOChange> list = new ArrayList<>();
for(ClassThatChange item : request){
ClassThatNOChange c = new ClassThatNOChange()
//here is the line of code that changes from report to report
c.setResult(callMethodB(item.getVariable2()));
list.add(c);
}
return Optional.of(callSameMethod(list));
}
The only thing that change is the callMethodA, or B, or C... but all of them return the same type of answer.
The ClassThatChange is something like this:
public class Father{
private Date date;
// then the getters and setters
}
public class Son extends Father{
private String description;
// then the getters and setters
}
All the classes that can change extends from the father.
Is there a way to reduce this repeat code?
Sorry for my bad English.
答案1
得分: 2
我认为你正在寻找的是一种方法，可以将每种情况中的类型转换为始终相同的类型。这可以通过Function或者你自己定义的自定义函数接口来实现。在这里，我展示了Function。
private <T> Optional<byte[]> convert(
List<? extends T> request,
Function<? super T, ? extends SomeTypeYouDidNotShow> conversion) {
if (request.isEmpty()) return Optional.empty();
List<ClassThatNOChange> list = request.stream()
.map(item -> {
ClassThatNOChange c = new ClassThatNOChange();
c.setResult(conversion.apply(item));
return c;
})
.collect(Collectors.toList());
return Optional.of(callSameMethod(list));
}
然后，你所有的重复方法都会类似于这样：
public Optional<byte[]> generateReportA(List<Father> request) {
return convert(request,
item -> callMethodA(item.getVariable1(), item.getVariable2()));
}
public Optional<byte[]> generateReportB(List<Son> request) {
return convert(request,
item -> callMethodB(item.getVariable2()));
}
英文:
I think what you are looking for is a way to plug in a conversion from the type that changes in each case to the type that is always the same. That could be done with a Function, or with a customized functional interface that you define. Here, I'm showing Function.
private <T> Optional<byte[]> convert(
List<? extends T> request,
Function<? super T, ? extends SomeTypeYouDidNotShow> conversion) {
if (request.isEmpty()) return Optional.empty();
List<ClassThatNOChange> list = request.stream()
.map(item -> {
ClassThatNOChange c = new ClassThatNOChange();
c.setResult(conversion.apply(item));
return c;
})
.collect(Collectors.toList());
return Optional.of(callSameMethod(list));
}
Then all your duplicate methods would look something like this:
public Optional<byte[]> generateReportA(List<Father> request) {
return convert(request,
item -> callMethodA(item.getVariable1(), item.getVariable2()));
}
public Optional<byte[]> generateReportB(List<Son> request) {
return convert(request,
item -> callMethodB(item.getVariable2()));
}
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