现在3天之后，我觉得在接下来的3天没有结果之前，最好先问一下。
当前情况：我通过PHP API获取数据作为JSON。 数据是parsend，我现在有一个图像的URL作为？String？。 实际上，URL在Listview中显示为文本URL。
现在问题是如何在listView中显示图像？
使用以下代码，URL在listView中显示为文本 - 这是有效的。
ListAdapter adapter = new SimpleAdapter(this, mProductMapList, R.layout.list_product_categories,
new String[] { KEY_ID, KEY_NAME, KEY_IMAGE},
new int[] { R.id.id,R.id.name, R.id.image});
new String[]{KEY_VER,KEY_NAME},new int[]{R.id.id,R.id.title});
mListView.setAdapter(adapter);
所以我认为Problm是SimpleAdapter。 我还创建了一个这样的custon适配器：
ListView list= (ListView) this.findViewById(R.id.list_view);
ListAdapter adapter =
new MyAdapter(
this,
mProductMapList,
R.layout.list_product_categories,
new String[]{KEY_ID,KEY_NAME,KEY_IMAGE},
new int[]{R.id.id,R.id.name,R.id.image});
list.setAdapter(adapter);
MyAdapter.java：
package com.learn2crack.listviewjson;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.SimpleAdapter;
import com.squareup.picasso.Picasso;
import java.util.List;
import java.util.Map;
/**
* Created by Michael on 07.11.2017.
*/
public class MyAdapter extends SimpleAdapter {
//String KEY_IMAGE = "image";
public MyAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String[] from, int[] to){
super(context, data, resource, from, to);
}
public View getView(int position, View convertView, ViewGroup parent){
// here you let SimpleAdapter built the view normally.
View v = super.getView(position, convertView, parent);
// Then we get reference for Picasso
ImageView img = (ImageView) v.getTag();
if(img == null){
img = (ImageView) v.findViewById(R.id.image);
v.setTag(img); // <<< THIS LINE !!!!
}
// get the url from the data you passed to the `Map`
// String url = ((Map)getItem(position)).get();
// do Picasso
Picasso.with(v.getContext()).load("http://copy-cat.at/wp-content/uploads/2014/06/as11.jpg").into(img);
// return the view
return v;
}
}
Full Shop.java（主要）
package com.learn2crack.listviewjson;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import com.learn2crack.listviewjson.model.AndroidVersion;
import com.learn2crack.listviewjson.model.ProductDetails;
import org.json.JSONObject;
import com.learn2crack.listviewjson.model.ResponseProduct;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Scanner;
import com.learn2crack.listviewjson.ImageAdapter;
import com.squareup.picasso.Picasso;
import com.squareup.picasso.Target;
public class Shop extends AppCompatActivity implements LoadJSONTaskShop.listenerShop, AdapterView.OnItemClickListener {
private ListView mListView;
private Context context;
ImageView imagee;
public static final String URL = "http://copy-cat.at/api/?act=getProductCategories";
//http://copy-cat.at/api/?act=getProductCategories
private List<HashMap<String, String>> mProductMapList = new ArrayList<>();
private static final String KEY_ID = "id";
private static final String KEY_NAME = "title";
private static final String KEY_IMAGE = "image";
private Spinner spinner1, spinner2;
private Button btnSubmit;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_shop);
Log.e("TESTLOGSHOP", "SHOP");
//instantiate your listView
// ListView nameAndAgeListView = (ListView) findViewById(R.id.gridview);
//create your listView with your custom object
// ArrayList<ImageAdapter> nameAndAgeList = new ArrayList<>();
mListView = (ListView) findViewById(R.id.list_view);
ImageView imagee= (ImageView) findViewById(R.id.image); // your imageview onbject
// context = this;
// String imageUri = "https://i.imgur.com/tGbaZCY.jpg";
// ImageView ivBasicImage = (ImageView) findViewById(R.id.imagee);
//Picasso.with(getApplicationContext()).load(imageUri).into(ivBasicImage);
// ImageView imageView = (ImageView) findViewById(R.id.image);
// Glide.with(this).load("http://i.imgur.com/DvpvklR.png").into(imageView);
// mListView.setOnItemClickListener(this);
// mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
// @Override
// public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {
// Intent i= new Intent(Shop.this,ShowProductDetails.class);
//Sring itemString= mProductMapList.get(arg2).get(KEY_VER);
// i.putExtra("productid",itemString);
// Log.e("TESTLOG", itemString);
// startActivity(i);
// finish();
// }
// });
new LoadJSONTaskShop(this).execute(URL);
getCategories();
addItemsOnSpinner2();
addListenerOnButton();
addListenerOnSpinnerItemSelection();
String URL ="";
// new LoadJSONTaskShop(this).execute(URL);
}
public void getCategories() {
String URL ="";
mListView = (ListView) findViewById(R.id.list_view);
// new LoadJSONTaskShop(this).execute(URL);
}
// add items into spinner dynamically
public void addItemsOnSpinner2() {
spinner2 = (Spinner) findViewById(R.id.spinner2);
String URL ="";
//new LoadJSONTaskShop(this).execute(URL);
List<String> list = new ArrayList<String>();
list.add("list 1");
list.add("list 2");
list.add("list 3");
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, list);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner2.setAdapter(dataAdapter);
}
public void addListenerOnSpinnerItemSelection() {
spinner1 = (Spinner) findViewById(R.id.spinner1);
spinner1.setOnItemSelectedListener(new CustomOnItemSelectedListener());
}
// get the selected dropdown list value
public void addListenerOnButton() {
spinner1 = (Spinner) findViewById(R.id.spinner1);
spinner2 = (Spinner) findViewById(R.id.spinner2);
btnSubmit = (Button) findViewById(R.id.btnSubmit);
btnSubmit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(Shop.this,
"OnClickListener : " +
"\nSpinner 1 : "+ String.valueOf(spinner1.getSelectedItem()) +
"\nSpinner 2 : "+ String.valueOf(spinner2.getSelectedItem()),
Toast.LENGTH_SHORT).show();
}
});
}
public void onClick(View v) {
startActivity(new Intent(this, Shop.class));
finish();
}
///////////
// @Override
public void onLoaded(List<ProductDetails> productDetails) {
for (ProductDetails android : productDetails) {
// HashMap<String, String> map = new HashMap<>();
HashMap<String, String> map = new HashMap<String, String>();
map.put(KEY_ID, android.getId());
map.put(KEY_NAME, android.getName());
map.put(KEY_IMAGE, android.getImage());
// new DownloadImage((ImageView) findViewById(R.id.image))
// .execute("http://copy-cat.at/wp-content/uploads/2014/06/as11.jpg");
String URL = "http://copy-cat.at/wp-content/uploads/2014/06/as11.jpg";
// new DownloadImage((ImageView) findViewById(R.id.imagee)).execute(URL);
new DownloadImage();
// Picasso.with(this).load("http://copy-cat.at/wp-content/uploads/2014/06/as11.jpg").into(imagee);
Log.e("TESTLOGSHOPxx", android.getImage());
mProductMapList.add(map);
}
loadListView();
}
@Override
public void onError() {
Toast.makeText(this, "Error !", Toast.LENGTH_SHORT).show();
}
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
// Toast.makeText(this, mProductMapList.get(i).get(KEY_NAME),Toast.LENGTH_LONG).show();
//ShowProduct.getProduct(this);
Toast.makeText(this, "Error !", Toast.LENGTH_SHORT).show();
}
private void loadListView() {
//ListAdapter adapter = new SimpleAdapter(this, mProductMapList, R.layout.list_product_categories,
// new String[] { KEY_ID, KEY_NAME, KEY_IMAGE},
// new int[] { R.id.id,R.id.name, R.id.image});
//new String[]{KEY_VER,KEY_NAME},new int[]{R.id.id,R.id.title});
// mListView.setAdapter(adapter);
ListView list= (ListView) this.findViewById(R.id.list_view);
ListAdapter adapter =
new MyAdapter(
this,
mProductMapList,
R.layout.list_product_categories,
new String[]{KEY_ID,KEY_NAME,KEY_IMAGE},
new int[]{R.id.id,R.id.name,R.id.image});
list.setAdapter(adapter);
}
// NAVIGATION
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main_menu, menu);
return true;
}
}
错误：
java.lang.IllegalArgumentException: Target must not be null.
at com.squareup.picasso.RequestCreator.into(RequestCreator.java:607)
at com.squareup.picasso.RequestCreator.into(RequestCreator.java:590)
at com.learn2crack.listviewjson.MyAdapter.getView(MyAdapter.java:37)
这里是 list_product_categories.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="@dimen/activity_vertical_margin">
<ImageView
android:id="@+id/flag"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:contentDescription="@string/search"
android:paddingTop="10dp"
android:paddingRight="10dp"
android:paddingBottom="10dp"
/>
<TextView
android:id="@+id/id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
/>
<TextView
android:id="@+id/name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp"
android:textSize="20dp"
android:textColor="#88000000"
android:layout_weight="1"
/>
<ImageView
android:id="@+id/imagee"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp"
android:textSize="20dp"
android:textColor="#88000000"
android:layout_weight="1"
/>
问题是什么？ 你可以在代码中看到我测试了更多来设置显示图像，但我是一个新手，它不是那么容易... 我希望你能帮帮我 ：） 非常感谢！
干杯，迈克尔
修改 现在我修复了很多很多，感谢你们！＃/ p>
解决方案：
// Then we get reference for Picasso
ImageView img = (ImageView) v.findViewById(R.id.imagee);
Log.e("", img.toString());
if(img == null){
img = (ImageView) v.findViewById(R.id.imagee);
v.setTag(img); // <<< THIS LINE !!!!
}
现在它的工作正常：）
答案 0 :(得分：0)
您的img变量为空（代码img = (ImageView) v.findViewById(R.id.image);显然无法正常工作），因此它会抱怨。