Listview 按钮点击监听器不工作

Question

我正在使用 adapter class 为我的项目设置值。每个项目都有一个 + 和一个 - 按钮。我有 foodActivity java class、activity_food 布局 java class 和 list_view_layout 列表。我已经在 activity class 中初始化了 + 和 - 按钮。 activity_food 启动时，应用程序崩溃。

list_view_layout 中的加号、减号和编辑文本 -

<Button
    android:id="@+id/minus"
    android:layout_width="35dp"
    android:layout_height="35dp"
    android:layout_below="@+id/foodname"
    android:layout_toEndOf="@+id/foodpic"
    android:text="-"
    android:textSize="12sp" />

<EditText
    android:id="@+id/quantity"
    android:layout_width="25dp"
    android:layout_height="30dp"
    android:layout_below="@+id/foodname"
    android:layout_toEndOf="@+id/minus"
    android:ems="10"
    android:inputType="number"
    android:textAlignment="center"
    android:background="@drawable/edittextbackground"
    android:text="0" />

<Button
    android:id="@+id/plus"
    android:layout_width="35dp"
    android:layout_height="35dp"
    android:layout_alignTop="@+id/quantity"
    android:layout_toEndOf="@+id/quantity"
    android:text="+"
    android:textSize="12sp" />

activity_food布局-

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.res.easyorder.foodActivity">

    <ListView
        android:id="@+id/listview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:divider="#ffff"
        android:dividerHeight="5dp"/>
</RelativeLayout>

我的适配器class -

package com.res.easyorder;


import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.zip.Inflater;

public class MyAdapter extends ArrayAdapter<item> {

    int q_ty = 0;
    ArrayList<item> foodlist = new ArrayList<>();

    public MyAdapter(Context context, int textViewResourceId, ArrayList<item> objects){

        super(context, textViewResourceId, objects);
        foodlist = objects;
    }

    @Override
    public int getCount(){

        return super.getCount();
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent){

        View v = convertView;
        LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = inflater.inflate(R.layout.list_view_layout, null);

        ImageView foodpic = (ImageView) v.findViewById(R.id.foodpic);
        TextView foodname = (TextView) v.findViewById(R.id.foodname);
        TextView foodprice = (TextView) v.findViewById(R.id.foodprice);
        Button plus = (Button) v.findViewById(R.id.plus);
        final EditText quantity = (EditText) v.findViewById(R.id.quantity);
        Button minus = (Button) v.findViewById(R.id.minus);

        plus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                item item = getItem(position);
                q_ty = Integer.parseInt(item.getQuantity());
                q_ty = q_ty + 1;
                quantity.setText("" +q_ty);
            }
        });


        foodname.setText(foodlist.get(position).getFoodName());
        foodpic.setImageResource(foodlist.get(position).getFoodImage());
        foodprice.setText("BDT: " +foodlist.get(position).getFoodPrice());
        quantity.setText(foodlist.get(position).getQuantity());

        return v;
    }
}

foodActivity java 代码。加减 onclicklistener 正在评论 -

package com.res.easyorder;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;

import java.util.ArrayList;

public class foodActivity extends AppCompatActivity {

    private String type = null;
    int quantity = 0;

    private Button plus, minus;
    private EditText q_ty;

    ListView simplelist;
    ArrayList<item> foodlist = new ArrayList<>();
    private FirebaseAuth firebaseAuth;

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

        firebaseAuth = FirebaseAuth.getInstance();
        simplelist = (ListView) findViewById(R.id.listview);

        plus = (Button) findViewById(R.id.plus);
        minus = (Button) findViewById(R.id.minus);
        q_ty = (EditText) findViewById(R.id.quantity);

        type = getIntent().getExtras().getString("type");

        if(type.equals("breakfast"))
        {
            foodlist.add(new item("Rooti",R.drawable.ruti,5));
            foodlist.add(new item("Parata",R.drawable.porata,8));
            foodlist.add(new item("Tandoor",R.drawable.tandoor,15));
            foodlist.add(new item("Vegetable",R.drawable.sodji,10));
            foodlist.add(new item("Daal",R.drawable.dal,10));
            foodlist.add(new item("Omelet",R.drawable.dimvaji,15));
            foodlist.add(new item("Singara",R.drawable.singara,8));
            foodlist.add(new item("Samosa",R.drawable.samosa,10));
            foodlist.add(new item("Puri",R.drawable.puri,5));

        }
        

        MyAdapter myAdapter = new MyAdapter(this,R.layout.list_view_layout,foodlist);
        simplelist.setAdapter(myAdapter);

        /*plus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                //quantity = quantity + 1;
                //q_ty.setText(""+quantity);
            }
        });

        minus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (quantity==0)
                {
                    //q_ty.setText(""+quantity);
                }

                else if (quantity>0)
                {
                    quantity = quantity - 1;
                    //q_ty.setText(""+quantity);
                }
            }
        });*/
    }

   
}

Answer 1

您必须在 "MyAdapter.getView(..)" 方法中设置 OnClicklistener，因为在该方法中创建项目。当前在您的 foodActivity.onCreate() 方法中，对象加号、减号和 q_ty 为空。

Answer 2

您遇到此问题是因为列表视图项目行 xml 文件中有加减按钮，并且您在 activity 中找到加减按钮。你必须把你的点击监听器放在你的适配器中 class

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    ViewHolder holder;

    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.list_entry, null);
        holder = new ViewHolder();
        holder.quantity= (EditText) convertView.findViewById(R.id.quantity);
        holder.plus = (Button) convertView.findViewById(R.id.plus);
        holder.minus = (Button) convertView.findViewById(R.id.minus);
        convertView.setTag(holder);
    }
    else {
        holder = (ViewHolder) convertView.getTag();
    }

    Item item = getItem(position);

    holder.quantity.setText(item.getQuantity());

    holder.plus.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

        Item item = getItem(position); 
        q_ty = Integer.parseInt(item.getQuantity()); 
        q_ty = q_ty + 1; 
        quantity.setText("" +q_ty);
        item.setQuantity(q_ty);
        }
    });



    return convertView;
}

Listview 按钮点击监听器不工作

Listview button click listener is not working

java

android

button

adapter

onclicklistener