我一直在尝试使用this tutorial了解如何在我的某些Android应用中使用自定义ArrayAdapter，但稍微调整一下以便我可以使用自己的应用程序。
我现在已经在手机上测试了几次，但我发现性能速度非常慢（加载和滚动列表视图时）。不使用此自定义ArrayAdapter的其他活动具有正常的性能速度。
我不确定问题是什么，或者我的代码会在哪里，所以下面，我发布了所有自定义ArrayAdapter类：
package com.mycompany.myapp;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.ArrayList;
public class CustomArrayAdapter extends ArrayAdapter<String> {
private static class ViewHolder {
TextView tv_Id;
TextView tv_Name;
TextView tv_Group;
}
private Context context;
private ArrayList<String> arr_items;
public CustomArrayAdapter(Context context, ArrayList<String> arr_items) {
super(context, R.layout.listview_advanced, arr_items);
this.context = context;
this.arr_items = arr_items;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
Person person = new Person(context, arr_items.get(position));
// Check if an existing view is being reused, otherwise inflate the view
ViewHolder viewHolder; // View lookup cache stored in tag
if (convertView == null) {
viewHolder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(getContext());
convertView = inflater.inflate(R.layout.listview_advanced, parent, false);
viewHolder.tv_Id = (TextView) convertView.findViewById(R.id.lvAdv_text1);
viewHolder.tv_Name = (TextView) convertView.findViewById(R.id.lvAdv_text2);
viewHolder.tv_Group = (TextView) convertView.findViewById(R.id.lvAdv_text3);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
// Populate the data into the template view using the data object
viewHolder.tv_Id.setText(person.getIDAsString());
viewHolder.tv_Name.setText(person.getName());
if (person.getGroup().equals("")) {
viewHolder.tv_Group.setText("");
} else {
viewHolder.tv_Group.setText("(" + person.getGroup() + ")");
}
// Return the completed view to render on screen
return convertView;
}
}
非常感谢任何帮助。感谢。
此外，在调用CustomArrayAdapter之前，我通过遍历ArrayList<String>文件的行并获取该数据，将数据添加到.csv。目前，在阅读.csv文件时，我有这个：
...
ArrayList<String> arr_person = new ArrayList<>(); // Global variable
...
// In a method:
String data = inputStream.nextLine();
String[] line = data.split(",");
if (line.length >1) {
arr_person.add(line[1]);
}
...
CustomArrayAdapter adapter = new CustomArrayAdapter(getActivity(), arr_person);
lv_main.setAdapter(adapter);
我如何针对对象进行调整？
我的Person对象的工作原理如下：
private Context context;
private String person, group, someAttribute, ... ;
private int idNumber, scoreOne, scoreTwo, scoreThree, scoreFour, scoreFive, scoreSix, scoreTotal, ... ;
private double ... ;
public Person(Context context, String person) {
this.context = context;
this.person = person;
loadInformation();
}
private void loadInformation() {
InputStreamReader inputStreamReader;
try {
inputStreamReader = new InputStreamReader(context.getAssets().open("PersonsList.csv"));
Scanner inputStream = new Scanner(inputStreamReader);
inputStream.nextLine(); // Ignores the first line
while (inputStream.hasNext()) {
String data = inputStream.nextLine(); // Gets a whole line
String[] line = data.split(","); // Splits the line up into a string array
if (line.length > 1) {
if (line[1].equals(person)) {
idNumber = Integer.parseInt(line[0]);
person = line[1];
group = line[2];
someAttribute = line[3];
scoreOne = Integer.parseInt(line[4]);
scoreTwo = Integer.parseInt(line[5]);
scoreThree = Integer.parseInt(line[6]);
scoreFour= Integer.parseInt(line[7]);
scoreFive = Integer.parseInt(line[8]);
scoreSix = Integer.parseInt(line[9]);
scoreTotal = scoreOne + scoreTwo + scoreThree + scoreFour + scoreFive + scoreSix;
// Same code pattern for defining about 10 more attributes
}
}
}
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public int getID() {
return idNumber;
}
public String getIDAsString() {
return format(idNumber);
}
private String format(int number) {
String str_num = String.valueOf(number);
switch (str_num.length()) {
case 1:
str_num = "00" + str_num;
break;
case 2:
str_num = "0" + str_num;
break;
case 3:
// Leave it how it is;
break;
}
return str_num;
}
public String getName() {
return person;
}
public String getGroup() {
return group;
}
public String getSomeAttribute() {
return someAttribute;
}
public int getScoreOne() {
return scoreOne;
}
public int getScoreTwo() {
return scoreTwo;
}
...
答案 0 :(得分：2)
将数组和ArrayAdapter基于Person而不是String，并在设置适配器之前列出Person s 。这样，您只需运行一次Person构造函数，而不是每次显示其视图。
ArrayList<Person> arr_person = new ArrayList<>(); // Global variable
...
String data = inputStream.nextLine();
String[] line = data.split(",");
if (line.length > 1) {
Person person = new Person(context, line[1]);
arr_person.add(person);
}
...
CustomArrayAdapter adapter = new CustomArrayAdapter(getActivity(), arr_person);
lv_main.setAdapter(adapter);
...
package com.mycompany.myapp;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.ArrayList;
public class CustomArrayAdapter extends ArrayAdapter<Person> {
private static class ViewHolder {
TextView tv_Id;
TextView tv_Name;
TextView tv_Group;
}
private Context context;
private ArrayList<Person> persons;
public CustomArrayAdapter(Context context, ArrayList<Person> persons) {
super(context, R.layout.listview_advanced, arr_items);
this.context = context;
this.persons = persons;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
Person person = persons.get(position);
// Check if an existing view is being reused, otherwise inflate the view
ViewHolder viewHolder; // View lookup cache stored in tag
if (convertView == null) {
viewHolder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(getContext());
convertView = inflater.inflate(R.layout.listview_advanced, parent, false);
viewHolder.tv_Id = (TextView) convertView.findViewById(R.id.lvAdv_text1);
viewHolder.tv_Name = (TextView) convertView.findViewById(R.id.lvAdv_text2);
viewHolder.tv_Group = (TextView) convertView.findViewById(R.id.lvAdv_text3);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
// Populate the data into the template view using the data object
viewHolder.tv_Id.setText(person.getIDAsString());
viewHolder.tv_Name.setText(person.getName());
if (person.getGroup().equals("")) {
viewHolder.tv_Group.setText("");
} else {
viewHolder.tv_Group.setText("(" + person.getGroup() + ")");
}
// Return the completed view to render on screen
return convertView;
}
}