如何使用 ArrayList HashMap 将 listview onItemClick 数据发送到另一个活动

Question

我对Android开发相当陌生。我这里有一个应用程序，它应该将staffList中的值发送到另一个活动。

查看员工活动.java

package com.example.activity.AdminModule;
import androidx.appcompat.app.AppCompatActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import com.example.helper.HttpHandler;
import com.example.login1.AppConfig;
import com.example.login1.MainActivity;
import com.example.login1.R;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
public class ViewStaffActivity extends AppCompatActivity {
private String TAG = ViewStaffActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView lv;

ArrayList<HashMap<String,String >> staffList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_staff);
staffList = new ArrayList<>();
lv = (ListView)findViewById(R.id.staffListView);

new GetStaff().execute();

}

private class GetStaff extends AsyncTask<Void,Void,Void> {
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(ViewStaffActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(AppConfig.URL_RETRIEVE_STAFF);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr.substring(jsonStr.indexOf("{"), jsonStr.lastIndexOf("}") + 1));
// Getting JSON Array node
JSONArray staffArray = jsonObj.getJSONArray("user");
// looping through All Staff
for (int i = 0; i < staffArray.length(); i++) {
JSONObject c = staffArray.getJSONObject(i);
String name = c.getString("name");
String email = c.getString("email");
String created_at = c.getString("created_at");
String user_type = c.getString("user_type");

// tmp hash map for single staff
HashMap<String, String> Staff = new HashMap<>();
// adding each child node to HashMap key => value
Staff.put("name", name);
Staff.put("email", email);
Staff.put("user_type", user_type);
Staff.put("created_at", created_at);
// adding contact to contact list
staffList.add(Staff);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat for possible errors!",
Toast.LENGTH_LONG)
.show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
ViewStaffActivity.this, staffList,
R.layout.list_item, new String[]{"name", "email",
"created_at","user_type"}, new int[]{R.id.name,
R.id.email, R.id.created_at,R.id.user_type});
lv.setAdapter(adapter);
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {


String test = staffList.get(position).toString();
Intent intent = new Intent(ViewStaffActivity.this,ProfileCRUD.class);
intent.putExtra("data",staffList.get(position));
startActivity(intent);
}
});
}
}

}

当我通过将.get(position).toString()分配给String test来测试是否有任何值时，它输出了我单击的正确值。

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {


String test = staffList.get(position).toString();
Intent intent = new Intent(ViewStaffActivity.this,ProfileCRUD.class);
intent.putExtra("data",staffList.get(position));
startActivity(intent);
}

但是当我使用intent将值传递给PROFILE_CRUD.java时，它会在此行返回name: null hashmap size : 4name.setText(hashMap.get("name"));

package com.example.activity.AdminModule;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
import com.example.login1.R;
import java.util.HashMap;

public class ProfileCRUD extends AppCompatActivity {
private TextView name;
private TextView email;
private TextView user_type;
private TextView created_at;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
name = (TextView)findViewById(R.id.nameTextView);
email = (TextView)findViewById(R.id.emailTextView);
user_type = (TextView)findViewById(R.id.userTypeTextView);
created_at = (TextView)findViewById(R.id.createdAtTextView);
/*Intent intent = getIntent();
HashMap<String, String> hashMap = (HashMap<String, String>)intent.getSerializableExtra("data");
String lat = hashMap.get("Coord_LAT");
String longi = hashMap.get("Coord_LONG");*/
Intent intent = getIntent();
HashMap<String, String> hashMap = (HashMap<String, String>)intent.getSerializableExtra("data");
name.setText(hashMap.get("name"));
email.setText(hashMap.get("email"));
user_type.setText(hashMap.get("user_type"));
created_at.setText(hashMap.get("created_at"));

任何帮助将不胜感激！

编辑在正确的解决方案的帮助下修复了它。name.setText返回 null 的原因是我的布局文件没有setContentView。

Answer 1

与其在意图中传递哈希映射，不如将每个值拆分到捆绑包中。这样：

Intent intent = new Intent(ViewStaffActivity.this,ProfileCRUD.class);
HashMap<String, String> hashMap = staffList.get(position);
Bundle extras = new Bundle();
extras.putString("NAME", hashmap.get("name"));
extras.putString("EMAIL", hashmap.get("email"));
extras.putString("USER_TYPE", hashmap.get("user_type"));
extras.putString("CREATED_AT", hashmap.get("created_at"));
intent.putExtras(extras);
startActivity(intent);

然后在另一个活动的 onCreate(( 中，您将使用：

Bundle extras = getIntent().getExtras();
String name = extras.get("NAME");
...

Answer 2

您可以将HashMap转换为json并通过Intent发送。 使用以下代码发送意图：

String jsonStaff = (new Gson()).toJson(staffList.get(position));
intent.putExtra("jsonStaff", jsonStaff);

并像风箱一样在另一项活动中获得意图：

String jsonStaff = intent.getStringExtra("jsonStaff");
HashMap<String,String > dataStaff = (new Gson()).fromJson(jsonStaff, new HashMap<String,String >().getClass());

仅此而已。