问题
The below is my testing code to create the list view, the list view display successfully, however, there is error in click event. I would like to create an intent to send a hardcode message to an new activity. However, it show error for the line
Intent intent = new Intent(context, SendMessage.class);
So , the problem is , what should I provide for this class?
Also , instead of hard code the output message, how to capture the data in list view row and pass to the new activity? e.g. BBB,AAA,R.drawable.tab1_hdpi for the first row.
Thanks.
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = \"com.example.ListViewTest.MESSAGE\";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<ListEntry> members = new ArrayList<ListEntry>();
members.add(new ListEntry(\"BBB\",\"AAA\",R.drawable.tab1_hdpi));
members.add(new ListEntry(\"ccc\",\"ddd\",R.drawable.tab2_hdpi));
members.add(new ListEntry(\"assa\",\"cxv\",R.drawable.tab3_hdpi));
members.add(new ListEntry(\"BcxsadvBB\",\"AcxdxvAA\"));
members.add(new ListEntry(\"BcxvadsBB\",\"AcxzvAA\"));
members.add(new ListEntry(\"BcxvBB\",\"AcxvAA\"));
members.add(new ListEntry(\"BvBB\",\"AcxsvAA\"));
members.add(new ListEntry(\"BcxvBB\",\"AcxsvzAA\"));
members.add(new ListEntry(\"Bcxadv\",\"AcsxvAA\"));
members.add(new ListEntry(\"BcxcxB\",\"AcxsvAA\"));
ListView lv = (ListView)findViewById(R.id.listView1);
Log.i(\"testTag\",\"before start adapter\");
StringArrayAdapter ad = new StringArrayAdapter (members,this);
Log.i(\"testTag\",\"after start adapter\");
Log.i(\"testTag\",\"set adapter\");
lv.setAdapter(ad);
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Intent intent = new Intent(context, SendMessage.class);
String message = \"abc\";
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
});
}
回答1:
I can not see where do you declare context. For the purpose of the intent creation you can use MainActivity.this
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Intent intent = new Intent(MainActivity.this, SendMessage.class);
String message = "abc";
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
});
To retrieve the object upon you have clicked you can use the AdapterView:
ListEntry entry = (ListEntry) parent.getItemAtPosition(position);
回答2:
ListView has the Item click listener callback. You should set the onItemClickListener in the ListView. Callback contains AdapterView and position as parameter. Which can give you the ListEntry.
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
ListEntry entry= (ListEntry) parent.getAdapter().getItem(position);
Intent intent = new Intent(MainActivity.this, SendMessage.class);
String message = entry.getMessage();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
});
回答3:
Error is coming in your code from this statement as you said
Intent intent = new Intent(context, SendMessage.class);
This is due to you are providing context of OnItemClickListener anonymous class into the Intent constructor but according to constructor of Intent
android.content.Intent.Intent(Context packageContext, Class<?> cls)
You have to provide context of you activity in which you are using intent that is the MainActivity class context. so your statement which is giving error will be converted to
Intent intent = new Intent(MainActivity.this, SendMessage.class);
Also for sending your message from this MainActivity to SendMessage class please see below code
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
ListEntry entry= (ListEntry) parent.getAdapter().getItem(position);
Intent intent = new Intent(MainActivity.this, SendMessage.class);
intent.putExtra(EXTRA_MESSAGE, entry.getMessage());
startActivity(intent);
}
});
Please let me know if this helps you
EDIT:- If you are finding some issue to get the value of list do one thing declear your array list
ArrayList<ListEntry> members = new ArrayList<ListEntry>();
globally i.e. before oncreate and change your listener as below
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Intent intent = new Intent(MainActivity.this, SendMessage.class);
intent.putExtra(EXTRA_MESSAGE, members.get(position));
startActivity(intent);
}
});
So your whole code will look as
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.ListViewTest.MESSAGE";
ArrayList<ListEntry> members = new ArrayList<ListEntry>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
members.add(new ListEntry("BBB","AAA",R.drawable.tab1_hdpi));
members.add(new ListEntry("ccc","ddd",R.drawable.tab2_hdpi));
members.add(new ListEntry("assa","cxv",R.drawable.tab3_hdpi));
members.add(new ListEntry("BcxsadvBB","AcxdxvAA"));
members.add(new ListEntry("BcxvadsBB","AcxzvAA"));
members.add(new ListEntry("BcxvBB","AcxvAA"));
members.add(new ListEntry("BvBB","AcxsvAA"));
members.add(new ListEntry("BcxvBB","AcxsvzAA"));
members.add(new ListEntry("Bcxadv","AcsxvAA"));
members.add(new ListEntry("BcxcxB","AcxsvAA"));
ListView lv = (ListView)findViewById(R.id.listView1);
Log.i("testTag","before start adapter");
StringArrayAdapter ad = new StringArrayAdapter (members,this);
Log.i("testTag","after start adapter");
Log.i("testTag","set adapter");
lv.setAdapter(ad);
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Intent intent = new Intent(MainActivity.this, SendMessage.class);
intent.putExtra(EXTRA_MESSAGE, members.get(position).getMessage());
startActivity(intent);
}
});
}
Where getMessage() will be a getter method specified in your ListEntry class which you are using to get message which was previously set.
回答4:
First, the class must implements the click listenener :
implements OnItemClickListener
Then set a listener to the ListView
yourList.setOnItemclickListener(this);
And finally, create the clic method:
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Toast.makeText(MainActivity.this, "You Clicked at ",
Toast.LENGTH_SHORT).show();
}
回答5:
//get main activity
final Activity main_activity=getActivity();
//list view click listener
final ListView listView = (ListView) inflatedView.findViewById(R.id.listView_id);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String stringText;
//in normal case
stringText= ((TextView)view).getText().toString();
//in case if listview has separate item layout
TextView textview=(TextView)view.findViewById(R.id.textview_id_of_listview_Item);
stringText=textview.getText().toString();
//show selected
Toast.makeText(main_activity, stringText, Toast.LENGTH_LONG).show();
}
});
//populate listview
回答6:
According to my test,
implements OnItemClickListener -> works.
setOnItemClickListener -> works.
ListView is clickable by default (API 19)
The important thing is, "click" only works to TextView (if you choose simple_list_item_1.xml as item). That means if you provide text data for the ListView, "click" works when you click on text area. Click on empty area does not trigger "click event".
来源：https://stackoverflow.com/questions/17851687/how-to-handle-the-click-event-in-listview-in-android