Question

变量'adapter'中的问题并声明final。我的IDE继续告诉“适配器”需要被声明为final，我在哪里以及如何做到这一点？这让我站起来了，我似乎无法继续前进。请帮忙。它在这里引用了这段代码和问题：Android ImageView from ListView

package com.example.androidhive;

import java.util.ArrayList;
import java.util.HashMap;

import android.content.Intent;
import android.widget.TextView;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;


public class CustomizedListView extends Activity {
    // All static variables
    static final String URL = "http://imforchange.org/international-movement-for-change/testing/data.xml";

    // XML node keys
    static final String KEY_EVENT = "event"; // parent node
    static final String KEY_ID = "eventId";
    static final String KEY_TITLE = "eventName";
    static final String KEY_DESCRIPTION = "eventDescription";
    static final String KEY_ABSTRACT = "eventAbstract";
    static final String KEY_DATE = "eventDate";
    static final String KEY_PRICE = "eventPrice";
    static final String KEY_LINK = "eventLink";
    static final String KEY_ADDRESS = "eventAddress";
    static final String KEY_CUSTOM_LINK = "eventCustomlink";
    static final String KEY_PICTURE = "eventPicture";
    static final String KEY_ICON = "eventIcon";

    ListView list;
    LazyAdapter adapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);


        ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
        LazyAdapter  adapter = new LazyAdapter(this, songsList);

        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL); // getting XML from URL
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_EVENT);
        // looping through all song nodes <song>
        for (int i = 0; i < nl.getLength(); i++) {
            // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();
            Element e = (Element) nl.item(i);
            // adding each child node to HashMap key => value
            map.put(KEY_ID, parser.getValue(e, KEY_ID));
            map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
            map.put(KEY_DESCRIPTION, parser.getValue(e, KEY_DESCRIPTION));
            map.put(KEY_ABSTRACT, parser.getValue(e, KEY_ABSTRACT));
            map.put(KEY_DATE, parser.getValue(e, KEY_DATE));
            map.put(KEY_PRICE, parser.getValue(e, KEY_PRICE));
            map.put(KEY_LINK, parser.getValue(e, KEY_LINK));
            map.put(KEY_ADDRESS, parser.getValue(e, KEY_ADDRESS));
            //map.put(KEY_CUSTOM_LINK, parser.getValue(e, KEY_CUSTOM_LINK));
            map.put(KEY_PICTURE, parser.getValue(e, KEY_PICTURE));
            map.put(KEY_ICON, parser.getValue(e, KEY_ICON));

            // adding HashList to ArrayList
            songsList.add(map);
        }


        list=(ListView)findViewById(R.id.list);

        // Getting adapter by passing xml data ArrayList
        adapter=new LazyAdapter(this, songsList);
        list.setAdapter(adapter);


        // Click event for single list row
        list.setOnItemClickListener(new OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                    // Get the item that was clicked

                    HashMap<String, String> map = adapter.getItem(position); 
                    // Starting new intent
                    Intent in = new Intent(getApplicationContext(), DetailView.class);
                    in.putExtra(KEY_TITLE, map.get(KEY_TITLE));
                    in.putExtra(KEY_PICTURE, map.get(KEY_PICTURE)); 
                    in.putExtra(KEY_DESCRIPTION, map.get(KEY_DESCRIPTION));
                    in.putExtra(KEY_PRICE, map.get(KEY_PRICE));
                    in.putExtra(KEY_LINK, map.get(KEY_LINK));
                    startActivity(in);
                }
        });     
    }
}

Answer 1

你没有发布你的代码声明你的变量“adapter”，但只是在它前面放了一个“final”修饰符，你应该没问题。

Answer 2

当您尝试在Overridden方法中访问外部变量时，例如“onItemClick”方法，您需要将该变量设为final。通过在变量声明前放置关键字“final”可以轻松完成。另一种方法是使该变量成为成员变量。查看此帖子以了解有关成员变量的更多信息。 https://stackoverflow.com/a/9332462/661074

Answer 3

你有三个选择：

将变量适配器设为字段
使变量适配器成为最终的局部变量
将变量适配器复制到另一个最终变量并使用该新变量内部类中的最终变量。

This Link解释了更多

可以从内部类中访问变量“适配器”。需要宣布最终

3 个答案: