尝试将变量信息从列表视图传递到新活动

Question

我是Android应用程序编程的新手，几天来我一直在努力通过单击从列表视图中的项目传递信息。我在这里发布我到目前为止所做的一切。

主要活动.java

public class MainActivity extends AppCompatActivity {
private LeagueAdapter mLeagueAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mLeagueAdapter = new LeagueAdapter();
final ListView listLeague = (ListView) findViewById(R.id.listView);
listLeague.setAdapter(mLeagueAdapter);

// Handle clicks on the ListView
listLeague.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapter, View view, int whichItem, long id) {
/*
Create  a temporary League
Which is a reference to the League
that has just been clicked
*/
// Create a new dialog window
//DialogShowLeague dialog = new DialogShowLeague();
// Send in a reference to the League to be shown
//dialog.sendLeagueSelected(tempLeague);
// Show the dialog window with the League in it
//dialog.show(getFragmentManager(), "");

String selected = ListView[whichItem];
Intent i = new Intent(getApplicationContext(), BowlersActivity.class);
i.putExtra("name", selected);
startActivity(i);
}
});
}
public void createNewLeague(League n){
mLeagueAdapter.addLeague(n);
}

@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) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
if (id == R.id.action_addLeague) {
DialogNewLeague dialog = new DialogNewLeague();
dialog.show(getFragmentManager(), "");
return true;
}
return super.onOptionsItemSelected(item);
}
public class LeagueAdapter extends BaseAdapter {
List<League> leagueList = new ArrayList<League>();
@Override
public int getCount() {
return leagueList.size();
}
@Override
public League getItem(int whichItem) {
// Returns the requested league
return leagueList.get(whichItem);
}
@Override
public long getItemId(int whichItem) {
// Method used internally
return whichItem;
}
@Override
public View getView(
int whichItem, View view, ViewGroup viewGroup) {
/*
Prepare a list item to show our data
The list item is contained in the view parameter
The position of the data in our ArrayList is contained
in whichItem parameter
*/

// Has view been inflated already
if(view == null){
// No. So do so here
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.single_league_list_item, viewGroup,false);
}// End if
// Grab a reference to all our TextView and ImageView widgets
TextView txtTitle = (TextView) view.findViewById(R.id.txtTitle);
// Hide any ImageView widgets that are not relevant
League tempLeague = leagueList.get(whichItem);
// Add the text to the heading and description
txtTitle.setText(tempLeague.getTitle());
return view;
}
public void addLeague(League n){
leagueList.add(n);
notifyDataSetChanged();
}

}
}

对话新联盟.java

public class DialogNewLeague extends DialogFragment {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
LayoutInflater inflater = getActivity().getLayoutInflater();
View dialogView = inflater.inflate(R.layout.dialog_new_league, null);
final EditText editTitle = (EditText) dialogView.findViewById(R.id.editTitle);
Button btnCancel = (Button) dialogView.findViewById(R.id.btnCancelLeague);
Button btnOK = (Button) dialogView.findViewById(R.id.btnAddLeague);
builder.setView(dialogView).setMessage("Add New mLeague");
btnCancel.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
dismiss();
}
});
// Handle the OK button
btnOK.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Create a new note
League newLeague = new League();
// Set its variables to match the users entries on the form
newLeague.setTitle(editTitle.getText().toString());
// Get a reference to MainActivity
MainActivity callingActivity = (MainActivity) getActivity();
// Pass newNote back to MainActivity
callingActivity.createNewLeague(newLeague);
// Quit the dialog
dismiss();
}
});

return builder.create();
}
}

联赛.java

package rvogl.ca.mydialog;
public class League {
private String mLeague;
public String getTitle() {
return mLeague;
}
public void setTitle(String mLeague) {
this.mLeague = mLeague;
}
}

保龄球手活动.java

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
public class BowlersActivity extends AppCompatActivity {
League mLeague;
String title;
String editText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bowlers);
Bundle extras = getIntent().getExtras();
String name = extras.getString("name");
editText.setText(name);
}
}

我已经浏览了这个网站上几乎所有我能找到的帖子，我已经尝试了其中的几个，但没有任何成功。

此时，当我单击联盟列表视图中的项目时，应用程序就会崩溃。

关于如何实现这一目标的任何建议和建议将不胜感激。

我能够使用以下方法将信息发送到警报对话框：

对话显示联盟

import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class DialogShowLeague extends DialogFragment {
League mLeague;
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
LayoutInflater inflater = getActivity().getLayoutInflater();
View dialogView = inflater.inflate(R.layout.dialog_show_league, null);
TextView txtTitle = (TextView) dialogView.findViewById(R.id.txtTitle);
txtTitle.setText(mLeague.getTitle());

Button btnOK = (Button) dialogView.findViewById(R.id.btnOK);
builder.setView(dialogView).setMessage("Your mLeague");
btnOK.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dismiss();
}
});

return builder.create();
}

public void sendLeagueSelected(League leagueSelected) {
mLeague = leagueSelected;
}
}

使用类似的东西无法完成此操作。 我只是不知道用什么替换对话框视图。

Answer 1

您可以在列表视图单击上传递值，就像下面的代码一样。在您的模型类中实现可序列化接口，即联盟

listLeague.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
@Override public void onItemClick(AdapterView<?> adapter, View view, int pos, long id) { 
League selected = (League)adaper.getItemAtPosition(pos);
Intent i = new Intent(getApplicationContext(), BowlersActivity.class); 
i.putExtra("name", (Serializable)selected);             
startActivity(i); 
}
});

编辑

将模型类替换为此

public class League implement Serializable { 
private String mLeague; 
public String getTitle() { 
return mLeague; 
} 
public void setTitle(String mLeague) {
this.mLeague = mLeague;
} 
}

获取有关第二次活动的数据，如下所示

String name = extras.getSerializableExtra("name").getTitle();

Answer 2

我已经使用以下代码设法解决了这个问题：

主活动

mLeagueAdapter = new LeagueAdapter();
final ListView listLeague = (ListView) findViewById(R.id.listView);
listLeague.setAdapter(mLeagueAdapter);
listLeague.setOnItemClickListener(new   AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapter, View view, int pos, long id) {
String leagueName = mLeagueAdapter.getItem(pos).getTitle();
Intent myIntent = new Intent(getBaseContext(), BowlersActivity.class);
myIntent.putExtra("value1", leagueName);
startActivity(myIntent);
}
});

在我的第二个活动投球手活动中.java

String savedExtra = getIntent().getStringExtra("value1");
TextView myText = (TextView) findViewById(R.id.tvLeagueName);
myText.setText(savedExtra);

我的问题是我试图从一个空变量"选定"中获取联赛名称 一旦我使用我的 mLeagueAdapter 在列表视图中单击了联赛的位置，通过 .putExtra 传递它就不再是问题了。

侯赛因@Fazal非常感谢您的耐心和帮助，非常感谢。