使用 BaseAdapter 在 ListView 中显示 ArrayList
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【中文标题】使用 BaseAdapter 在 ListView 中显示 ArrayList【英文标题】：Showing ArrayList in ListView using BaseAdapter 【发布时间】：2016-01-10 19:41:00 【问题描述】：我很难在 ArrayList 中的 ListView 中显示数据。我使用BaseAdapter 来显示数据。我不知道为什么它不起作用。执行此部分时，我的应用程序刚刚停止工作。这是我的代码：
ItemAnalysisRecord.java
package com.checkaidev1;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
public class ItemAnalysisRecord extends Activity
Context ctx = this;
ListView listview1;
DatabaseOperations dbOperations;
List<ItemAnalysis> itemAnalysisList;
BaseAdapter myAdapter = new BaseAdapter()
@Override
public View getView(int position, View convertView, ViewGroup parent)
// TODO Auto-generated method stub
if (convertView != null)
return convertView;
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.item_analysis_row, parent, false);
TextView itemNumberTextView = (TextView) rowView.findViewById(R.id.itemNumberTextView);
itemNumberTextView.setText(getItemAnalysisData().get(position).getItemNumber());
Log.i("Database Operations", "Evaluation: " + itemNumberTextView);
TextView correctKeyTextView = (TextView) rowView.findViewById(R.id.correctKeyTextView);
correctKeyTextView.setText(getItemAnalysisData().get(position).getCorrectKey());
Log.i("Database Operations", "Evaluation: " + correctKeyTextView);
TextView itemDifficultyTextView= (TextView) rowView.findViewById(R.id.itemDifficultyTextView);
itemDifficultyTextView.setText(Double.toString(getItemAnalysisData().get(position).getItemDifficulty()));
Log.i("Database Operations", "Evaluation: " + itemDifficultyTextView);
TextView itemEvaluationTextView= (TextView) rowView.findViewById(R.id.itemEvaluationTextView);
itemEvaluationTextView.setText(getItemAnalysisData().get(position).getEvaluation());
Log.i("Database Operations", "Evaluation: " + itemEvaluationTextView);
return rowView;
@Override
public long getItemId(int arg0)
// TODO Auto-generated method stub
return 0;
@Override
public Object getItem(int arg0)
// TODO Auto-generated method stub
return null;
@Override
public int getCount()
// TODO Auto-generated method stub
itemAnalysisList = getItemAnalysisData();
return itemAnalysisList.size();
;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.item_analysis_record);
Log.i("CheckAide", "OnCreate Method Called");
dbOperations = new DatabaseOperations(ctx);
TextView examNameTextView = (TextView)findViewById(R.id.examNameTextView);
examNameTextView.setText("Exam: " + dbOperations.getExam(ExamRecord.listviewIndex).getExamName());
TextView examDateTextView = (TextView)findViewById(R.id.examDateTextView);
examDateTextView.setText("Exam Date: " + dbOperations.getExam(ExamRecord.listviewIndex).getExamDate());
listview1 = (ListView) findViewById(R.id.listview1);
View header = (View)getLayoutInflater().inflate(R.layout.item_analysis_header, null);
listview1.addHeaderView(header);
listview1.setAdapter(myAdapter);
public List<ItemAnalysis> getItemAnalysisData()
int correctStudent = 0;
String evaluation = null;
List<ItemAnalysis> itemAnalysisList = new ArrayList<ItemAnalysis>();
int itemNumberCtr = dbOperations.getItemCount(ExamRecord.listviewIndex);
int studentIDctr = dbOperations.getStudentCount(ExamRecord.listviewIndex);
for(int x = 1; x <= itemNumberCtr; x++)
ItemAnalysis itemAnalysis = new ItemAnalysis();
itemAnalysis.setItemNumber(x);
Log.i("Database Operations", "Item Number: " + x);
String correctKey = dbOperations.getCorrectKey(ExamRecord.listviewIndex, x);
itemAnalysis.setCorrectKey(correctKey);
Log.i("Database Operations", "Correct Key: " + correctKey);
for(int y = 1 ; y <= studentIDctr; y++)
String answeredKey = dbOperations.getAnsweredKey(x, y);
Log.i("Database Operations", "Answered Key: " + answeredKey);
if (answeredKey.equalsIgnoreCase(correctKey))
correctStudent++;
Log.i("Database Operations", "CorrectStudent: " + correctStudent);
DecimalFormat df = new DecimalFormat("0.00");
double itemDifficulty = Double.valueOf(df.format((double)correctStudent / (double)studentIDctr));
itemAnalysis.setItemDifficulty(itemDifficulty);
Log.i("Database Operations", "Correct Student: " + correctStudent + "StudentIDCtr:" + studentIDctr + "Item Difficulty " + itemDifficulty);
correctStudent = 0;
if (itemDifficulty <= 0.20)
evaluation = "VD";
else if (itemDifficulty <= 0.40 && itemDifficulty >= 0.21)
evaluation = "D";
else if (itemDifficulty <= 0.60 && itemDifficulty >= 0.41)
evaluation = "MD";
else if (itemDifficulty <= 0.80 && itemDifficulty >= 0.61)
evaluation = "E";
else if (itemDifficulty <= 1.00 && itemDifficulty >= 0.81)
evaluation = "VE";
itemAnalysis.setEvaluation(evaluation);
Log.i("Database Operations", "Evaluation: " + evaluation);
itemAnalysisList.add(itemAnalysis);
Log.i("Database Operations", "data added ");
return itemAnalysisList;
ItemAnalysis.java
package com.checkaidev1;
public class ItemAnalysis
public int itemNumber;
public String correctKey;
public double itemDifficulty;
public String evaluation;
// Empty constructor
public ItemAnalysis()
public ItemAnalysis(int itemNumber, String correctKey, double itemDifficulty, String evaluation)
this.itemNumber = itemNumber;
this.correctKey = correctKey;
this.itemDifficulty = itemDifficulty;
this.evaluation = evaluation;
// getting name
public int getItemNumber()
return this.itemNumber;
// setting name
public void setItemNumber(int itemNumber)
this.itemNumber = itemNumber;
// getting name
public String getCorrectKey()
return this.correctKey;
// setting name
public void setCorrectKey(String correctKey)
this.correctKey = correctKey;
public double getItemDifficulty()
return this.itemDifficulty;
// setting name
public void setItemDifficulty(double itemDifficulty)
this.itemDifficulty = itemDifficulty;
public String getEvaluation()
return this.evaluation;
// setting name
public void setEvaluation(String evaluation)
this.evaluation = evaluation;
我希望有人能帮我解决这个问题。提前感谢您的帮助。
【问题讨论】：
能否请您发布 logcat 错误报告 【参考方案1】：您的适配器实例定位字段区域。 在我的情况下，适配器实例何时使用空（只是'new ArrayList（）'）arrayList创建，它不起作用。
所以我在 arrayList 填充数据后将适配器实例化为局部变量。
【讨论】：
【参考方案2】：在你的活动中删除那个baseadapter并做如下操作
首先创建单独的适配器类，如下所示
public class ItemsAdapter extends BaseAdapter
List<ItemAnalysis> itemAnalysisList;
Context mContext;
public ItemsAdapter(Context context, List<ItemAnalysis> itemAnalysisList1)
this.mContext = context;
this.itemAnalysisList = itemAnalysisList1;
@Override
public View getView(int position, View convertView, ViewGroup parent)
// TODO Auto-generated method stub
if (convertView != null)
return convertView;
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.item_analysis_row, parent, false);
ItemAnalysis itemDomain = itemAnalysisList.get(position);
TextView itemNumberTextView = (TextView) rowView.findViewById(R.id.itemNumberTextView);
itemNumberTextView.setText(itemDomain.getItemNumber());
Log.i("Database Operations", "Evaluation: " + itemNumberTextView);
TextView correctKeyTextView = (TextView) rowView.findViewById(R.id.correctKeyTextView);
correctKeyTextView.setText(itemDomain.getCorrectKey());
Log.i("Database Operations", "Evaluation: " + correctKeyTextView);
TextView itemDifficultyTextView= (TextView) rowView.findViewById(R.id.itemDifficultyTextView);
itemDifficultyTextView.setText(Double.toString(itemDomain.getItemDifficulty()));
Log.i("Database Operations", "Evaluation: " + itemDifficultyTextView);
TextView itemEvaluationTextView= (TextView) rowView.findViewById(R.id.itemEvaluationTextView);
itemEvaluationTextView.setText(itemDomain.getEvaluation());
Log.i("Database Operations", "Evaluation: " + itemEvaluationTextView);
return rowView;
@Override
public long getItemId(int arg0)
// TODO Auto-generated method stub
return 0;
@Override
public Object getItem(int arg0)
// TODO Auto-generated method stub
return null;
@Override
public int getCount()
// TODO Auto-generated method stub
return itemAnalysisList.size();
然后将Adapter类全局声明为
private ItemsAdapter adapter;
将此getItemAnalysisData() 方法的返回类型更改为void
现在将getItemAnalysisData()方法中的适配器类初始化为
adapter = new ItemsAdapter(this,your_arraylist);
list.setadapter(adapter);
【讨论】：
【参考方案3】：不要初始化你的ArrayList..否则我在你的代码中没有发现任何问题..
是的，将条件放在getView() 中，如下所示..
试试这个..
@Override
public View getView(int position, View convertView, ViewGroup parent)
View rowView = convertView;
if (rowView == null)
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
rowView = inflater.inflate(R.layout.main, parent, false);
//---- your code----
return rowView;
【讨论】：
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