英文:
How do I pass parameters/argument to a callback function?
问题
以下是翻译好的部分：
一个天真的问题，因为我对编程有点新手。我正在开发一个 Android 应用程序，需要将参数传递给回调方法（不确定用词是否正确）。
我希望这些参数/变量在主函数中可用。我正在调用调用者来调用我的主函数，因此需要从调用者传递参数。
就像经典函数所做的那样：
示例
method(param1, param2);
function method(param1, param2){
Log(param1 + param2);
....
}
我需要以下代码来实现与上面示例相同的功能。
代码如下：
// 调用者：
getChioceList(new MyCallback() {
@Override
public void onCallback(ArrayList<String> value) {
Log.d("TAG", "Config CallBack " + value);
}
});
// 接口
public interface MyCallback{
void onCallback(ArrayList<String> value);
}
// 主函数：我希望向这个方法传递一些参数
public void getChioceList(final MyCallback myCallback) {
final ArrayList<String> result = new ArrayList<>();
final DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query query = ref.child("Device").orderByChild("home").equalTo(homeID);
query.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot dataSnapshots: dataSnapshot.getChildren()) {
result.add(dataSnapshots.getKey());
Log.i(TAG, "Config: get Input 3 " + result);
}
myCallback.onCallback(result);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {}
});
}
请帮忙...
英文:
A naive question as I am a bit new to programming.
I am Working on an Android application where I need to pass parameters to the callback method(Not sure if the verbiage is right).
I want the parameters/variables to be available to the Main Function. I am calling the Caller to invoke my main function and hence need the parameters to pass from the Caller.
something like the classic functions does
Example
method(param1, param2);
function method(param1, param2){
Log(param1 + param 2);
....
}
I need the below code to achieve the functionality as the above example
the code is as follows:
//Caller:-
getChioceList(new MyCallback() {
@Override
public void onCallback(ArrayList<String> value) {
Log.d("TAG", "Config CallBack " + value);
}
});
//Interface
public interface MyCallback{
void onCallback(ArrayList<String> value);
}
//Main function : I want some parameters to be passed to this method
public void getChioceList(final MyCallback myCallback) {
final ArrayList < String > result = new ArrayList < > ();
final DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query query = ref.child("Device").orderByChild("home").equalTo(homeID);
query.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot dataSnapshots: dataSnapshot.getChildren()) {
result.add(dataSnapshots.getKey());
Log.i(TAG, "Config: get Input 3 " + result);
}
myCallback.onCallback(result);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {}
});
}
Please help...
答案1
得分: 0
基于我理解的内容。基本上您想要将一些内容传递给回调方法。
我建议创建另一个类来实现 ValueEventListener。
像这样：
public class SomeClassThatWillImplement implements ValueEventListener {
private String cVar1;
private String cVar2;
public SomeClassThatWillImplement(String param1, String param2) {
this.cVar1 = param1;
this.cVar2 = param2;
}
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
// 使用 this.cVar1 做一些事情
// 使用 this.cVar2 做一些事情
for (DataSnapshot dataSnapshots : dataSnapshot.getChildren()) {
result.add(dataSnapshots.getKey());
Log.i(TAG, "Config: get Input 3 " + result);
}
myCallback.onCallback(result);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
// 使用 this.cVar1 做一些事情
// 使用 this.cVar2 做一些事情
}
}
要使用上面的类，
public void getChoiceList(final MyCallback myCallback) {
final ArrayList<String> result = new ArrayList<>();
final DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query query = ref.child("Device").orderByChild("home").equalTo(homeID);
query.addListenerForSingleValueEvent(new SomeClassThatWillImplement(param1, param2));
}
希望这有所帮助。
英文:
Based on what i understand. Basically you want to pass something to a callback method.
I would suggest to create another class that will implement ValueEventListener.
Like so
public class SomeClassThatWillImplement implements ValueEventListener {
private String cVar1;
private String cVar2;
public SomeClassThatWillImplement (String param1, String parma2) {
this.cVar1 = param1;
this.cVar2 = param2;
}
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
//Do something with this.cVar1
//Do something with this.cVar2
for (DataSnapshot dataSnapshots : dataSnapshot.getChildren()) {
result.add(dataSnapshots.getKey());
Log.i(TAG, "Config: get Input 3 " + result);
}
myCallback.onCallback(result);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
//Do something with this.cVar1
//Do something with this.cVar2
}
}
To use above class,
public void getChioceList(final MyCallback myCallback) {
final ArrayList<String> result = new ArrayList<>();
final DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query query = ref.child("Device").orderByChild("home").equalTo(homeID);
query.addListenerForSingleValueEvent(new SomeClassThatWillImplement(param1, param2));
}
Hopefully this helps
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