单击 ImageView 时，showPopupMenu 方法不起作用答案

【问题标题】：showPopupMenu method not working when clickng on ImageView单击 ImageView 时，showPopupMenu 方法不起作用
【发布时间】：2017-08-11 17:47:20
【问题描述】：

我在列表视图的每个项目中都有一个弹出菜单。当您单击左侧的图像视图（设置为 3 个点的 img）时，应显示一个弹出菜单。但是，我遇到了错误

Could not find a method showPopupMenu(View) in the activity class android.app.Application for onClick handler on view class android.widget.ImageView with id 'settings_img'

有谁知道这个错误是什么。很明显找不到方法，但是是因为找不到类/视图吗？如果是这样，我该如何解决？谢谢主要活动

package com.example.george.hostscanmenus;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.PopupMenu;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    List hostList;
    ArrayAdapter<String> hostAdapter;
    PopupMenu popup;
    String subnet = "192.168.10.";
    ListView listView;

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

        hostList = new ArrayList<String>();

        //populating host addresses
        for(int i = 0; i < 255; i++) {
            hostList.add(subnet+i +"-aa:bb:00:cc:33:ee");
        }

        //inflating adapter
        listView = (ListView) findViewById(R.id.scan_list);
        hostAdapter = new ArrayAdapter<String>(getApplicationContext(), R.layout.host_item, R.id.ip_address, hostList);
        listView.setAdapter(hostAdapter);


    }

    /* code for popup menu in listview */
    public void showPopupMenu(View v) {
        popup = new PopupMenu(this, v);
        popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
            @Override
            public boolean onMenuItemClick(MenuItem menuItem) {
                switch (menuItem.getItemId()) {
                    case R.id.change_icon:
                        Toast.makeText(getApplicationContext(), menuItem.getTitle(), Toast.LENGTH_SHORT).show();
                        return true;
                    case R.id.notifications:
                        Toast.makeText(getApplicationContext(), menuItem.getTitle(), Toast.LENGTH_SHORT).show();
                        return true;
                    default:
                        return MainActivity.super.onContextItemSelected(menuItem);
                }
            }
        });
        MenuInflater inflater = popup.getMenuInflater();
        inflater.inflate(R.menu.host_menu, popup.getMenu());
        popup.show();
    }
}

数组适配器

package com.example.george.hostscanmenus;

import android.content.Context;
import android.support.annotation.NonNull;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by george on 8/11/17.
 */

public class HostAdapter extends ArrayAdapter<String> {

    public HostAdapter(Context context, int num, ArrayList<String> allHost) {
        super(context, 0, allHost);
    }

    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        String host = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.activity_main, parent, false);
        }
        // Lookup view for data population
        ImageView nodeHostImgView = (ImageView) convertView.findViewById(R.id.host_icon);
        TextView nodeIpTxtView = (TextView) convertView.findViewById(R.id.ip_address);
        TextView nodeMacTxtView = (TextView) convertView.findViewById(R.id.mac_address);
        ImageView nodeArrowImgView = (ImageView) convertView.findViewById(R.id.port_scan_arrow);
        // Populate the data into the template view using the data object
        nodeHostImgView.setImageResource(R.drawable.ic_computer_white_24dp);
        nodeIpTxtView.setText(host.substring(0,host.indexOf("-")));
        nodeMacTxtView.setText(host.substring(host.indexOf("-")));
        nodeArrowImgView.setImageResource(R.drawable.ic_keyboard_arrow_right_white_24dp);
        // Return the completed view to render on screen
        return convertView;
    }


}

主xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:ads="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:id="@+id/scan_list_linear"
    tools:context=".MainActivity">

    <!-- labels for ip / mac addres list -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/list_label">

        <TextView
            android:id="@+id/host_port_label"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.20"
            android:text="Host"
            android:textSize="20dp"
            android:textAlignment="center"
            android:textColor="@color/colorAccent"/>

        <TextView
            android:id="@+id/ip_open_label"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.80"
            android:textSize="20dp"
            tools:text="IP / MAC"
            android:paddingLeft="10dp"
            android:textColor="@color/colorAccent"/>

        <TextView
            android:id="@+id/scan_label"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.20"
            android:text="Scan"
            android:textSize="20dp"
            android:textAlignment="center"
            android:textColor="@color/colorAccent"/>


    </LinearLayout>

    <!--Listview to display scan output-->
    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/scan_list"/>

</LinearLayout>

列表项 xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <LinearLayout
        android:id="@+id/text_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <ImageView
            android:id="@+id/settings_img"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="0.10"
            android:padding="3dp"
            android:src="@drawable/ic_action_more_vert"
            android:onClick="showPopupMenu"/>

        <ImageView
            android:id="@+id/host_icon"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="0.20"
            android:padding="5dp"
            android:src="@drawable/ic_computer_white_24dp"/>

        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.50"
            android:orientation="vertical"
            android:paddingLeft="0dp"
            >

            <TextView
                android:id="@+id/ip_address"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textSize="18dp"
                tools:text="192.168.10.100"
                />

            <TextView
                android:id="@+id/mac_address"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textSize="16dp"
                tools:text="aa:bb:cc:00:11:22"
                />
        </LinearLayout>

        <ImageView
            android:id="@+id/port_scan_arrow"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="0.20"
            android:padding="5dp"
            android:src="@drawable/ic_keyboard_arrow_right_white_24dp"/>

    </LinearLayout>
</RelativeLayout>

菜单xml

<!-- listview menu for host scan options eg:
     change hostname, icon, notification etc -->
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <!-- Settings, should always be in the overflow -->
    <item android:id="@+id/change_icon"
        android:title="change icon"
        />


    <item android:id="@+id/notifications"
        android:title="set notification"
        />

</menu>

【问题讨论】：

您应该在您的适配器类中使用showPopupMenu() 逻辑，不要忘记将上下文传递给适配器..
如何从适配器上的 mainActivity 访问上下文。我虽然上下文被传递给适配器构造函数

标签： android xml listview android-menu popupmenu

【解决方案1】：

你应该在你的适配器 getView 上定义你的 settings_img 并为每个元素添加一个点击监听器。

示例：

ImageView settingsImgView = (ImageView) convertView.findViewById(R.id.settings_img);

settingsImgView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            context.showPopupMenu() //or popupmenu logic in here if you want
        }
    });

【讨论】：

在适配器类中？
settingsImage.setOnClickListener() 是否进入适配器的 getView() 方法中？
我添加了这段代码进行测试，但没有发生任何事情 settingImgView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Toast.makeText(getContext(), "hello world ", Toast.LENGTH_SHORT).show(); } }); // 返回

【解决方案2】：

通常，当涉及到适配器时，我会传递活动本身而不是上下文。然后我将活动的上下文传递给 super() 并将活动保存在字段变量中。这样我就可以使用父活动的所有公共方法。

【讨论】：