2020年5月5日 21:28:31go评论80阅读模式

英文:

Get button call from another class

问题

我有两个类`OrderAdapter.java`和`OrderActivity.java`。在类`OrderAdapter.java`中有一个按钮，当我点击它时，它应该更改类`OrderActivity.java`中的一个文本视图。当我运行应用程序时，文本视图会因为这一行而改变：

```java
textView_order_price.setText(adapter.totalAmount + "");

但是当我再次点击按钮时，它不应该再次更改文本，但实际上没有发生变化。你能帮我解决这个问题吗？

OrderActivity.java

package com.nfc.netvision;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

import java.util.ArrayList;

public class OrderActivity extends AppCompatActivity {

    RecyclerView recyclerView;
    TextView textView_order_price;
    ArrayList<ModelOrder> orderArrayList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_order);

        recyclerView = findViewById(R.id.recyclerview_order_scroll);
        textView_order_price = findViewById(R.id.textView_order_price);

        orderArrayList = new ArrayList<>();
        orderArrayList.add(new ModelOrder(R.drawable.coke, "Coka Cola", "Eine Cola hält dich wach und schmeckt dazu.", "3", 0));
        orderArrayList.add(new ModelOrder(R.drawable.fastfood, "Pommes", "Fritten für die Titten.", "5", 0));
        orderArrayList.add(new ModelOrder(R.drawable.water, "Wasser", "Still und sanft, so mag ich es.", "5", 0));
        orderArrayList.add(new ModelOrder(R.drawable.burger, "Burger", "Ach mir fällt nichts ein.", "10", 0));

        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        RecyclerView.LayoutManager recLiLayoutManager = layoutManager;

        recyclerView.setLayoutManager(recLiLayoutManager);

        OrderAdapter adapter = new OrderAdapter(this, orderArrayList);

        recyclerView.setAdapter(adapter);
        textView_order_price.setText(adapter.totalAmount + "");
        System.out.println(adapter.totalAmount + "TOASBTORT");

    }
}

OrderAdapter.java

package com.nfc.netvision;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.google.firestore.v1.StructuredQuery;
import java.util.ArrayList;
public class OrderAdapter extends RecyclerView.Adapter<OrderAdapter.ViewHolder> {
    public int totalAmount;
    private Context mContext;
    private ArrayList<ModelOrder> nList;
    OrderAdapter(Context context, ArrayList<ModelOrder> list) {
        mContext = context;
        nList = list;
    }
    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater layoutInflater = LayoutInflater.from(mContext);
        View view = layoutInflater.inflate(R.layout.recyclerview_order_items, parent, false);
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;
    }
    @Override
    public void onBindViewHolder(@NonNull final ViewHolder holder, int position) {
        final ModelOrder orderItem = nList.get(position);
        ImageView image = holder.item_image;
        final TextView name, place, price;
        name = holder.item_name;
        place = holder.item_place;
        price = holder.item_price;
        image.setImageResource(orderItem.getImage());
        name.setText(orderItem.getName());
        place.setText(orderItem.getPlace());
        price.setText(orderItem.getPrice());
        holder.order_item_minus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(orderItem.getCounter() > 0) {
                    orderItem.setCounter(orderItem.getCounter()-1);
                    holder.order_item_count.setText("" + orderItem.getCounter());
                    calculatePrice(Integer.parseInt((String) price.getText()), false);
                }
            }
        });
        holder.order_item_plus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(orderItem.getCounter() < 9) {
                    orderItem.setCounter(orderItem.getCounter() + 1);
                    holder.order_item_count.setText("" + orderItem.getCounter());
                    calculatePrice(Integer.parseInt((String) price.getText()), true);
                }
            }
        });
    }
    @Override
    public int getItemCount() {
        return nList.size();
    }
    public class ViewHolder extends RecyclerView.ViewHolder {
        ImageView item_image;
        TextView item_name, item_place, item_price, order_item_minus, order_item_count, order_item_plus;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            item_image = itemView.findViewById(R.id.order_item_image);
            item_name = itemView.findViewById(R.id.order_item_name);
            item_place = itemView.findViewById(R.id.order_item_place);
            item_price = itemView.findViewById(R.id.order_item_price);
            order_item_minus = itemView.findViewById(R.id.order_item_minus);
            order_item_plus = itemView.findViewById(R.id.order_item_plus);
            order_item_count = itemView.findViewById(R.id.order_item_count);
        }
    }
    public void calculatePrice(int pPrice, boolean pUpDown) {
        if(pUpDown) {
            totalAmount = totalAmount + pPrice;
        }
        else {
            totalAmount = totalAmount - pPrice;
        }
        System.out.println(totalAmount);
    }
}

英文:

I have the two classes OrderAdapter.java OrderActivity.java. In the class OrderAdapter.java is a button and when i click it has to change a textview in the class OrderActivity.java. When i run the app the textview changes one time because of this line which is intend:
textView_order_price.setText(adapter.totalAmount + "");

but when i press the button again it should change the text again but it doesn't. Can you guys help me?

OrderActivity.java

package com.nfc.netvision;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import java.util.ArrayList;
public class OrderActivity extends AppCompatActivity {
RecyclerView recyclerView;
TextView textView_order_price;
ArrayList&lt;ModelOrder&gt; orderArrayList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order);
recyclerView = findViewById(R.id.recyclerview_order_scroll);
textView_order_price = findViewById(R.id.textView_order_price);
orderArrayList = new ArrayList&lt;&gt;();
orderArrayList.add(new ModelOrder(R.drawable.coke, &quot;Coka Cola&quot;, &quot;Eine Cola h&#228;lt dich wach und schmeckt dazu.&quot;, &quot;3&quot;,0));
orderArrayList.add(new ModelOrder(R.drawable.fastfood, &quot;Pommes&quot;, &quot;Fritten f&#252;r die Titten.&quot;, &quot;5&quot;,0));
orderArrayList.add(new ModelOrder(R.drawable.water, &quot;Wasser&quot;, &quot;Still und sanft, so mag ich es.&quot;, &quot;5&quot;,0));
orderArrayList.add(new ModelOrder(R.drawable.burger, &quot;Burger&quot;, &quot;Ach mir f&#228;llt nichts ein.&quot;, &quot;10&quot;,0));
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
RecyclerView.LayoutManager recLiLayoutManager = layoutManager;
recyclerView.setLayoutManager(recLiLayoutManager);
OrderAdapter adapter = new OrderAdapter(this, orderArrayList);
recyclerView.setAdapter(adapter);
textView_order_price.setText(adapter.totalAmount + &quot;&quot;);
System.out.println(adapter.totalAmount + &quot;TOASBTORT&quot;);
}
}

OrderAdapter.java

package com.nfc.netvision;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.google.firestore.v1.StructuredQuery;
import java.util.ArrayList;
public class OrderAdapter extends RecyclerView.Adapter&lt;OrderAdapter.ViewHolder&gt; {
public int totalAmount;
private Context mContext;
private ArrayList&lt;ModelOrder&gt; nList;
OrderAdapter(Context context, ArrayList&lt;ModelOrder&gt; list) {
mContext = context;
nList = list;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(mContext);
View view = layoutInflater.inflate(R.layout.recyclerview_order_items, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(@NonNull final ViewHolder holder, int position) {
final ModelOrder orderItem = nList.get(position);
ImageView image = holder.item_image;
final TextView name, place, price;
name = holder.item_name;
place = holder.item_place;
price = holder.item_price;
image.setImageResource(orderItem.getImage());
name.setText(orderItem.getName());
place.setText(orderItem.getPlace());
price.setText(orderItem.getPrice());
holder.order_item_minus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(orderItem.getCounter() &gt; 0) {
orderItem.setCounter(orderItem.getCounter()-1);
holder.order_item_count.setText(&quot;&quot; + orderItem.getCounter());
calculatePrice(Integer.parseInt((String) price.getText()), false);
}
}
});
holder.order_item_plus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(orderItem.getCounter() &lt; 9) {
orderItem.setCounter(orderItem.getCounter() + 1);
holder.order_item_count.setText(&quot;&quot; + orderItem.getCounter());
calculatePrice(Integer.parseInt((String) price.getText()), true);
}
}
});
}
@Override
public int getItemCount() {
return nList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
ImageView item_image;
TextView item_name, item_place, item_price,order_item_minus,order_item_count, order_item_plus;
public ViewHolder(@NonNull View itemView) {
super(itemView);
item_image = itemView.findViewById(R.id.order_item_image);
item_name = itemView.findViewById(R.id.order_item_name);
item_place = itemView.findViewById(R.id.order_item_place);
item_price = itemView.findViewById(R.id.order_item_price);
order_item_minus = itemView.findViewById(R.id.order_item_minus);
order_item_plus = itemView.findViewById(R.id.order_item_plus);
order_item_count = itemView.findViewById(R.id.order_item_count);
}
}
public void calculatePrice(int pPrice, boolean pUpDown) {
if(pUpDown) {
totalAmount = totalAmount + pPrice;
}
else {
totalAmount = totalAmount - pPrice;
}
System.out.println(totalAmount);
}
}

答案1

得分: 0

2种解决问题的方法：

第一种方法 - 非常简单 - 只需将您的textView从活动添加到构造适配器中；

private TextView orderPrice;

OrderAdapter(Context context, ArrayList<ModelOrder> list, TextView orderPrice) {
    mContext = context;
    nList = list;
    this.orderPrice = orderPrice;
}

public void calculatePrice(int pPrice, boolean pUpDown) {
    if (pUpDown) {
        totalAmount = totalAmount + pPrice;
    } else {
        totalAmount = totalAmount - pPrice;
    }
    // 在这里将totalAmount添加到您的活动中的textView
    orderPrice.setText(Integer.toString(totalAmount));
    System.out.println(totalAmount);
}

第二种方法，在适配器中创建接口，并在活动中实现它；

public class OrderAdapter extends RecyclerView.Adapter<OrderAdapter.ViewHolder> {
    // ... 其他代码 ...

    interface TotalListener {
        void onTotalChanged(String result);
    }

    OrderAdapter(Context context, ArrayList<ModelOrder> list, TotalListener listener) {
        mContext = context;
        nList = list;
        this.listener = listener;
    }

    // ... 其他代码 ...

    public void calculatePrice(int pPrice, boolean pUpDown) {
        // ... 计算逻辑 ...

        // 这是回调到您的活动
        listener.onTotalChanged(Integer.toString(totalAmount));
        System.out.println(totalAmount);
    }
}

// ... 其他代码 ...

public class OrderActivity extends AppCompatActivity implements OrderAdapter.TotalListener {
    // ... 其他代码 ...

    @Override
    public void onTotalChanged(String result) {
        textView_order_price.setText(result);
    }
}

英文:

2 ways to solve your problem:

1st way - very simple - just add your textView from activity to constructor adapter;

private TextView orderPrice;
OrderAdapter(Context context, ArrayList&lt;ModelOrder&gt; list,TextView orderPrice) {
mContext = context;
nList = list;
this.orderPrice = orderPrice;
}
public void calculatePrice(int pPrice, boolean pUpDown) {
if(pUpDown) {
totalAmount = totalAmount + pPrice;
}
else {
totalAmount = totalAmount - pPrice;
}
//here you add totalAmount to your textView in activity
orderPrice.setText(totalAmount.toString)
System.out.println(totalAmount);
}

2d way create interface in your adapter and implement it in your activity;

//1st create interface in your adapter like this:

public class OrderAdapter extends 
RecyclerView.Adapter&lt;OrderAdapter.ViewHolder&gt; {
public int totalAmount;
private Context mContext;
private ArrayList&lt;ModelOrder&gt; nList;
private TotalListener listener;
interface TotalListener{
void onTotalChanged(String result);
}
OrderAdapter(Context context, ArrayList&lt;ModelOrder&gt; list,TotalListener listener) {
mContext = context;
nList = list;
this.listener = listener;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(mContext);
View view = layoutInflater.inflate(R.layout.recyclerview_order_items, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(@NonNull final ViewHolder holder, int position) {
final ModelOrder orderItem = nList.get(position);
ImageView image = holder.item_image;
final TextView name, place, price;
name = holder.item_name;
place = holder.item_place;
price = holder.item_price;
image.setImageResource(orderItem.getImage());
name.setText(orderItem.getName());
place.setText(orderItem.getPlace());
price.setText(orderItem.getPrice());
holder.order_item_minus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(orderItem.getCounter() &gt; 0) {
orderItem.setCounter(orderItem.getCounter()-1);
holder.order_item_count.setText(&quot;&quot; + orderItem.getCounter());
calculatePrice(Integer.parseInt((String) price.getText()), false);
}
}
});
holder.order_item_plus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(orderItem.getCounter() &lt; 9) {
orderItem.setCounter(orderItem.getCounter() + 1);
holder.order_item_count.setText(&quot;&quot; + orderItem.getCounter());
calculatePrice(Integer.parseInt((String) price.getText()), true);
}
}
});
}
@Override
public int getItemCount() {
return nList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
ImageView item_image;
TextView item_name, item_place, item_price,order_item_minus,order_item_count, order_item_plus;
public ViewHolder(@NonNull View itemView) {
super(itemView);
item_image = itemView.findViewById(R.id.order_item_image);
item_name = itemView.findViewById(R.id.order_item_name);
item_place = itemView.findViewById(R.id.order_item_place);
item_price = itemView.findViewById(R.id.order_item_price);
order_item_minus = itemView.findViewById(R.id.order_item_minus);
order_item_plus = itemView.findViewById(R.id.order_item_plus);
order_item_count = itemView.findViewById(R.id.order_item_count);
}
}
public void calculatePrice(int pPrice, boolean pUpDown) {
if(pUpDown) {
totalAmount = totalAmount + pPrice;
}
else {
totalAmount = totalAmount - pPrice;
}
//this is callback to your activity
listener.onTotalChanged(totalAmount.toString)
System.out.println(totalAmount);
}

}

and this is your updated activity

 public class OrderActivity extends AppCompatActivity impelemts OrderAdapter.TotalListener {
RecyclerView recyclerView;
TextView textView_order_price;
ArrayList&lt;ModelOrder&gt; orderArrayList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order);
recyclerView = findViewById(R.id.recyclerview_order_scroll);
textView_order_price = findViewById(R.id.textView_order_price);
orderArrayList = new ArrayList&lt;&gt;();
orderArrayList.add(new ModelOrder(R.drawable.coke, &quot;Coka Cola&quot;, &quot;Eine Cola h&#228;lt dich wach und schmeckt dazu.&quot;, &quot;3&quot;,0));
orderArrayList.add(new ModelOrder(R.drawable.fastfood, &quot;Pommes&quot;, &quot;Fritten f&#252;r die Titten.&quot;, &quot;5&quot;,0));
orderArrayList.add(new ModelOrder(R.drawable.water, &quot;Wasser&quot;, &quot;Still und sanft, so mag ich es.&quot;, &quot;5&quot;,0));
orderArrayList.add(new ModelOrder(R.drawable.burger, &quot;Burger&quot;, &quot;Ach mir f&#228;llt nichts ein.&quot;, &quot;10&quot;,0));
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
RecyclerView.LayoutManager recLiLayoutManager = layoutManager;
recyclerView.setLayoutManager(recLiLayoutManager);
OrderAdapter adapter = new OrderAdapter(this, orderArrayList,this);
recyclerView.setAdapter(adapter);
textView_order_price.setText(adapter.totalAmount + &quot;&quot;);
System.out.println(adapter.totalAmount + &quot;TOASBTORT&quot;);
}
@Override
public void onTotalChanged(String result) {
textView_order_price.setText(result);
}

}

答案2

得分: 0

将此侦听器添加到您的适配器类中，当单击按钮监听器时调用：

private OnButtonClickListener listener;

public void setOnButtonClickListener(OnButtonClickListener listener){
    this.listener = listener;
}

public interface OnButtonClickListener{
    void OnButtonClick();
}

在适配器的按钮点击事件中：

listener.OnButtonClick();

在您的活动类中：

OrderAdapter adapter = new OrderAdapter(this, orderArrayList);
adapter.setOnButtonClickListener(new OnButtonClickListener () {
    @Override
    public void OnButtonClick() {
        // 在这里您可以对文本视图进行任何操作
    }
});

英文:

add this listener to your adpater class and when you clik button listner call

private OnButtonClickListener listener;
public void setOnButtonClickListener(OnButtonClickListener listener){
this.listener=listener;
}
public interface OnButtonClickListener{
void OnButtonClick();
}

in Button click in your adapter :

listener.OnButtonClick();

in your activty class

OrderAdapter adapter = new OrderAdapter(this, orderArrayList);
adapter.setOnButtonClickListener(new OnButtonClickListener () {
@Override
public void OnButtonClick() {
//here you can do any thing on your text view 
}
});

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从另一个类获取按钮调用。

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