I'm new to Java and Android and am trying to figure out how to write a ListView and load the ListView from where it is saved.
I have ListView and each item on the ListView has a string and bool that changes if a checkbox for the item is checked or unchecked. I have a working method to add items to the ListView and am now trying to figure out how to write the ListView to a textfile.
I got some code for saving the ListView by clicking a menu item and them I'm trying to load it when I re-run the program in my OnCreate, but nothing is loading. I'm not sure if its the write or load that is not working or both.
Here is a class I made that works with my ListView.
Item.java
public class Item {
String name;
boolean isChecked = false;
public Item(String name) {this.name = name;}
public Item(String name, boolean checked){
this.name = name;
this.isChecked = checked;
}
@Override
public String toString(){
return name;
}
}
Here is my MainActivity.java that includes my saveList() and readFile()
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getName();
ArrayList<Item> items = new ArrayList<>();
private ListView lv;
private static final String sFile = "Saved.txt";
protected ListView getListView() {
if (lv == null) {
lv = (ListView) findViewById(android.R.id.list);
}
return lv;
}
protected void setListAdapter(ListAdapter adapter) {
getListView().setAdapter(adapter);
}
protected ListAdapter getListAdapter() {
ListAdapter adapter = getListView().getAdapter();
if (adapter instanceof HeaderViewListAdapter) {
return ((HeaderViewListAdapter) adapter).getWrappedAdapter();
} else {
return adapter;
}
}
private void deleteList()
{
if (!items.isEmpty())
{
items.clear();
}
lv.invalidateViews();
}
private void deleteCheckedItems()
{
SparseBooleanArray checked = lv.getCheckedItemPositions();
for(int i = 0; i < lv.getCount(); i++)
{
if (checked.get(i)==true)
{
items.remove(i);
}
lv.invalidateViews();
}
lv.clearChoices();
}
private void saveList(ArrayList<Item> itemlist) {
try {
OutputStreamWriter out = new OutputStreamWriter(openFileOutput(sFile, 0));
int iCnt = 0;
String allstring = "";
for (Item s : items)
{
if (s.isChecked)
{
iCnt++;
if (iCnt < items.size()) {
String thisstring;
thisstring = s.name + "\r\n";
out.write(thisstring);
allstring += thisstring;
} else {
String thisstring;
thisstring = s.name;
out.write(thisstring);
allstring += thisstring;
}
}
}
out.close();
//Toast.makeText(activity, allstring + " Written", duration).show();
}
catch (java.io.FileNotFoundException e)
{
}
catch (Exception ex)
{
// Toast.makeText(activity, "Write Exception : " + ex.getMessage(), duration).show();
}
}
public String readFile(ArrayList<Item> itemsList)
{
String sRet = "Nothing";
try
{
InputStream is = openFileInput(sFile);
if (is != null)
{
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String sLine;
StringBuffer sb = new StringBuffer();
while ((sLine = br.readLine()) != null)
sb.append(sLine + "\r\n");
is.close();
sRet = sb.toString();
// Toast.makeText(Toast.LENGTH_LONG).show();
}
}
catch (java.io.FileNotFoundException e)
{
}
catch (Exception ex)
{
// Toast.makeText(activi"Read Exception" + ex.getMessage(), Toast.LENGTH_LONG).show();
}
return sRet;
}
private void addItemDialog()
{
LayoutInflater inflater = LayoutInflater.from(this);
final View addView = inflater.inflate(R.layout.add, null);
new AlertDialog.Builder(this)
.setTitle("Add Item")
.setView(addView)
.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
EditText txtAdd = (EditText) addView.findViewById(R.id.etInput);
String sItem = (txtAdd).getText().toString();
items.add(new Item(sItem));
for (int i = 0; i < items.size(); i++)
{
lv.setItemChecked(i, items.get(i).isChecked);
}
}
})
.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
}
}).show();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setListAdapter(new ArrayAdapter<Item>(this, android.R.layout.simple_list_item_multiple_choice, items));
lv = this.getListView();
for (int i = 0; i < items.size(); i++)
{
lv.setItemChecked(i, items.get(i).isChecked);
}
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
readFile(items);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()){
case R.id.add_item:
addItemDialog();
return true;
case R.id.clear_all:
deleteList();
return true;
case R.id.clear_checked:
deleteCheckedItems();
return true;
case R.id.write:
saveList(items);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
put your oncreate method above after declaration that means after this line
private static final String sFile = "Saved.txt";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
.......
.......
//your code
}
//other method
Read Android activity lifecyle for better understanding