我正在开发一个Android应用，其中第一页是主页。点击主页上的任何项目，用户可以查看该项目中的详细信息。详细信息来自sqlite数据库，可由用户在应用程序中接受或拒绝。在用户接受或拒绝时，详细信息将从详细信息列表中删除。但是，当从详细信息页面单击后退按钮时，当用户再次到达主页时，会出现这样的问题：当用户再次单击同一项目时，它会显示所有详细信息而不保存状态。
E.g。如果我的item1有10个详细信息..我查看详细信息页面中的所有10个详细信息..然后接受2 ..所以总共保留8 ..但是当我点击返回并到达主页并再次点击item1时，它显示再次全部10 ...并且不记录2被接受时发生的变化。
如何解决这个问题？
这是我们正在处理的代码：
package com.sql.nigel;
import java.util.ArrayList;
public class listActivity extends ListActivity implements
android.view.View.OnClickListener,OnItemClickListener{
private ArrayList<listActivity2> m_orders = null;
private OrderAdapter m_adapter;
private Runnable viewOrders;
private SQLiteDatabase database;
private MySQLiteHelper dbHelper=new MySQLiteHelper(this);
private String[] leave_Col = {"Requester","LeaveType","No_of_Days","FromDate","ToDate"};
private String[] Cart_Col = {"CartNo","Date","Description","TotalValue","TotalTax","BudgetValue","UniqueNo"};
private String[] Time_Col = {"Name","Date","Project","Client","Tasks","FromDate","ToDate"};
private String[] Travel_Col = {"Requester","Purpose","Location","Cost","Date","Description","FromDate","ToDate","Hotel","Taxi","AdditionalExp"};
private String[] Invoice_Col = {"InvoiceNo","VendorName","Date","InvoiceValue","Date","VendorNo","PostingDate","FiscalYear","Pln_Group"};
private String[] Purchase_Col = {"PONo","Date","Vendor","OrderValue","PurchasingOrg","ApprovedVendor","Requester","Notes","RelatedInfo","QualityScore"};
String table_name;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listactivity);
database = dbHelper.getWritableDatabase();
table_name=this.getIntent().getExtras().getString("activity");
Button backButton = (Button)findViewById(R.id.back);
backButton.setOnClickListener(this);
Button selectButton = (Button)findViewById(R.id.select);
selectButton.setOnClickListener(this);
/* ImageView rightarrow = (ImageView)findViewById(R.id.rightarrow);
rightarrow.setOnClickListener(this);*/
m_orders = new ArrayList<listActivity2>();
this.m_adapter = new OrderAdapter(this, R.layout.listactivity2, m_orders);
setListAdapter(this.m_adapter);
ListView listView=(ListView)findViewById(android.R.id.list);
listView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
if(table_name.compareTo("LeaveRequest")==0){
Intent intent = new Intent(listActivity.this, leavedetails.class);
Bundle b = new Bundle(); //Create bundle
b.putInt("key",position); //Your id
intent.putExtras(b); //Put your id to your next Intent
startActivity(intent); //Call intent
}else if(table_name.compareTo("Time")==0){
Intent intent = new Intent(listActivity.this, timedetails.class);
Bundle b = new Bundle(); //Create bundle
b.putInt("key",position); //Your id
intent.putExtras(b); //Put your id to your next Intent
startActivity(intent); //Call intent
}else if(table_name.compareTo("ShoppingCart")==0){
Intent intent = new Intent(listActivity.this, cartdetails.class);
Bundle b = new Bundle(); //Create bundle
b.putInt("key",position); //Your id
intent.putExtras(b); //Put your id to your next Intent
startActivity(intent); //Call intent
}else if(table_name.compareTo("Invoice")==0){
Intent intent = new Intent(listActivity.this, invoicedetails.class);
Bundle b = new Bundle(); //Create bundle
b.putInt("key",position); //Your id
intent.putExtras(b); //Put your id to your next Intent
startActivity(intent); //Call intent
}else if(table_name.compareTo("PurchaseOrder")==0){
Intent intent = new Intent(listActivity.this, purchasedetails.class);
Bundle b = new Bundle(); //Create bundle
b.putInt("key",position); //Your id
intent.putExtras(b); //Put your id to your next Intent
startActivity(intent); //Call intent
}else if(table_name.compareTo("Travel")==0){
Intent intent = new Intent(listActivity.this, traveldetails.class);
Bundle b = new Bundle(); //Create bundle
b.putInt("key",position); //Your id
intent.putExtras(b); //Put your id to your next Intent
startActivity(intent); //Call intent
}
}
});
viewOrders = new Runnable(){
public void run() {
getOrders();
}
};
Thread thread = new Thread(null, viewOrders, "MagentoBackground");
thread.start();
}
private Runnable returnRes = new Runnable() {
public void run() {
if(m_orders != null && m_orders.size() > 0){
m_adapter.notifyDataSetChanged();
for(int i=0;i<m_orders.size();i++)
m_adapter.add(m_orders.get(i));
}
m_adapter.notifyDataSetChanged();
}
};
private void getOrders(){
try{
m_orders = new ArrayList<listActivity2>();
if(table_name.compareTo("LeaveRequest")==0){display_Leave();
}else if(table_name.compareTo("Time")==0){display_Time();
}else if(table_name.compareTo("ShoppingCart")==0){display_Cart();
}else if(table_name.compareTo("Invoice")==0){display_Invoice();
}else if(table_name.compareTo("PurchaseOrder")==0){display_Purchase();
}else if(table_name.compareTo("Travel")==0){display_Travel();
}
Log.i("ARRAY", ""+ m_orders.size());
} catch (Exception e) {
Log.e("BACKGROUND_PROC", e.getMessage());
}
runOnUiThread(returnRes);
database.close();
}
public void display_Leave(){
TextView heading=(TextView)findViewById(R.id.heading);
heading.setText("Leave Request");
Cursor c_L = database.query("LeaveRequest",leave_Col, null, null, null, null, null);
c_L.moveToFirst();
while (!c_L.isAfterLast()) {
listActivity2 o1 = new listActivity2();
o1.setOrdertext1(""+c_L.getString(0));
o1.setOrdertext2(""+c_L.getString(2)+" days");
o1.setOrdertext3(""+c_L.getString(1)+" ");
o1.setOrdertext4(""+c_L.getString(3)+" to "+c_L.getString(4));
m_orders.add(o1);
c_L.moveToNext();
} c_L.close();
}
public void display_Time(){
TextView heading=(TextView)findViewById(R.id.heading);
heading.setText("Time Booking");
Cursor c_L = database.query("Time",Time_Col, null, null, null, null, null);
c_L.moveToFirst();
while (!c_L.isAfterLast()) {
listActivity2 o1 = new listActivity2();
o1.setOrdertext1(""+c_L.getString(0));
o1.setOrdertext2(""+c_L.getString(3));
o1.setOrdertext3(""+c_L.getString(2)+" ");
o1.setOrdertext4(""+c_L.getString(1));
m_orders.add(o1);
c_L.moveToNext();
} c_L.close();
}
public void display_Cart(){
TextView heading=(TextView)findViewById(R.id.heading);
heading.setText("Shopping Cart");
Cursor c_L = database.query("ShoppingCart",Cart_Col, null, null, null, null, null);
c_L.moveToFirst();
while (!c_L.isAfterLast()) {
listActivity2 o1 = new listActivity2();
o1.setOrdertext1(""+c_L.getString(0));
o1.setOrdertext2("");
o1.setOrdertext3(""+c_L.getString(2)+" ");
o1.setOrdertext4(""+c_L.getString(1));
m_orders.add(o1);
c_L.moveToNext();
} c_L.close();
}
public void display_Invoice(){
TextView heading=(TextView)findViewById(R.id.heading);
heading.setText("Invoice Approval");
Cursor c_L = database.query("Invoice",Invoice_Col, null, null, null, null, null);
c_L.moveToFirst();
while (!c_L.isAfterLast()) {
listActivity2 o1 = new listActivity2();
o1.setOrdertext1(""+c_L.getString(1));
o1.setOrdertext2("");
o1.setOrdertext3(""+c_L.getString(0)+" ");
o1.setOrdertext4(""+c_L.getString(2));
m_orders.add(o1);
c_L.moveToNext();
} c_L.close();
}
public void display_Purchase(){
TextView heading=(TextView)findViewById(R.id.heading);
heading.setText("Purchase Order");
Cursor c_L = database.query("PurchaseOrder",Purchase_Col, null, null, null, null, null);
c_L.moveToFirst();
while (!c_L.isAfterLast()) {
listActivity2 o1 = new listActivity2();
o1.setOrdertext1(""+c_L.getString(0));
o1.setOrdertext2(""+c_L.getString(3));
o1.setOrdertext3(""+c_L.getString(2)+" ");
o1.setOrdertext4(""+c_L.getString(1));
m_orders.add(o1);
c_L.moveToNext();
} c_L.close();
}
public void display_Travel(){
TextView heading=(TextView)findViewById(R.id.heading);
heading.setText("Travel Approval");
Cursor c_L = database.query("Travel",Travel_Col, null, null, null, null, null);
c_L.moveToFirst();
while (!c_L.isAfterLast()) {
listActivity2 o1 = new listActivity2();
o1.setOrdertext1(""+c_L.getString(1));
o1.setOrdertext2(""+c_L.getString(3));
o1.setOrdertext3(""+c_L.getString(2)+" ");
o1.setOrdertext4(""+c_L.getString(4));
m_orders.add(o1);
c_L.moveToNext();
} c_L.close();
}
private class OrderAdapter extends ArrayAdapter<listActivity2> {
private ArrayList<listActivity2> items;
public OrderAdapter(Context context, int textViewResourceId, ArrayList<listActivity2> items) {
super(context, textViewResourceId, items);
this.items = items;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.listactivity2, null);
}
listActivity2 o = items.get(position);
if (o != null) {
TextView t1 = (TextView) v.findViewById(R.id.textList1);
TextView t2 = (TextView) v.findViewById(R.id.textList2);
TextView t3 = (TextView) v.findViewById(R.id.textList3);
TextView t4 = (TextView) v.findViewById(R.id.textList4);
if (t1 != null) {
t1.setText(o.getOrdertext1());
}
if(t2 != null){
t2.setText(o.getOrdertext2());
}
if(t3 != null){
t3.setText(o.getOrdertext3());
}
if(t4 != null){
t4.setText(o.getOrdertext4());
}
}
return v;
}
}
public void onClick(View v) {
switch(v.getId())
{
case R.id.back:
Intent backIntent = new Intent(listActivity.this, SqlTwoActivity.class);
startActivity(backIntent);
break;
case R.id.select:
Intent selectIntent = new Intent(listActivity.this, checkappear.class);
selectIntent.putExtra("checkappear", table_name);
startActivity(selectIntent);
break;
/*
case R.id.rightarrow:
Intent rightarrow = new Intent(listActivity.this, listActivity.class);
startActivity(rightarrow);
break;*/
}
}
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
// TODO Auto-generated method stub
}
}
答案 0 :(得分：0)
很难在代码中找到数据库调用。一些通用指南：
首先，您需要在单独的线程中封装对数据库的所有调用。 完成后，请务必关闭光标和数据库连接。 最好是使用AsyncTask。查看一些使用SQLite和AsyncTask的教程 - 它将自动为您处理单独的线程。
第二 - 阅读关于Activity Stack的内容，以便@Peter告诉你的内容是有道理的。