如何从回收器视图中的项目中获取数据，并在editText上的其他活动中查看它

Question

当用户登录用户可以创建其帐户的活动时，会打开(CreateProfileActivity(。创建配置文件后，用户将重定向到recyclerView活动，在该活动中，他们的配置文件信息将显示在recyclerView中。当用户单击recyclerView中的项目时，更新活动将打开。我希望他们的配置文件信息从recyclerView加载到更新活动中。请帮忙。

第页。S.由于我没有让CreateProfile_Activity只打开过一次，因为我不希望用户创建多个配置文件，所以现在：我运行了一次应用程序并创建了一个帐户，然后我更改了它，所以现在当用户登录时，它会打开recyclerView_Activity。

这是回收器View_Activity

package com.example.insert_update_activity;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class recyclerView_Activity extends AppCompatActivity {
// Button insertBtn;
RecyclerView recyclerView;
DBHelper myDB;
ArrayList<String> temp_id, temp_name, temp_age;
myAdapter myAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_recycler_view);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
/*       insertBtn = (Button) findViewById(R.id.insertBtn);
insertBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(recyclerView_Activity.this, Insert_Activity.class);
startActivity(intent);
}
});*/
myDB = new DBHelper(recyclerView_Activity.this);
temp_id = new ArrayList<>();
temp_name = new ArrayList<>();
temp_age = new ArrayList<>();
storeDataInArrays();
myAdapter = new myAdapter(recyclerView_Activity.this, this, temp_id, temp_name, temp_age);
recyclerView.setAdapter(myAdapter);
recyclerView.setLayoutManager(new LinearLayoutManager(recyclerView_Activity.this));
}
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1)
{
recreate();
}
}
void storeDataInArrays() {
Cursor cursor = myDB.readData();  // Cursor cursor = myDB.readAllData();
if (cursor.getCount() == 0)
{
Toast.makeText(recyclerView_Activity.this, "No Data", Toast.LENGTH_SHORT).show();
}
else
{
while (cursor.moveToNext()) {
temp_id.add(cursor.getString(0));
temp_name.add(cursor.getString(1));
temp_age.add(cursor.getString(2));

}
}
}
}

这是UpdateActivity

package com.example.insert_update_activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
public class Update_Activity extends AppCompatActivity {
EditText name, age;
Button updateBtn;
String id;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_update);
name = (EditText) findViewById(R.id.edit_name);
age = (EditText) findViewById(R.id.edit_age);
updateBtn = (Button) findViewById(R.id.updateBtn);
updateBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String sName = name.getText().toString().trim();
String sAge = age.getText().toString().trim();
DBHelper db = new DBHelper(Update_Activity.this);
db.updateData(id, sName, sAge);
Intent intent = new Intent(Update_Activity.this, com.example.insert_update_activity.recyclerView_Activity.class);
startActivity(intent);
}
});
getAndSetIntentData();
}
void getAndSetIntentData() {
if (getIntent().hasExtra("id") && getIntent().hasExtra("Name") && getIntent().hasExtra("Age"))
{
// Getting data from Intent
id = getIntent().getStringExtra("id");
String NAME = getIntent().getStringExtra("Name");
String AGE = getIntent().getStringExtra("Age");
// Setting Intent Data
name.setText(NAME);
age.setText(AGE);
}
else
{
Toast.makeText(Update_Activity.this, "No Data", Toast.LENGTH_SHORT).show();
}
}
}

这是DBHelper

package com.example.insert_update_activity;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;
import androidx.annotation.Nullable;
public class DBHelper extends SQLiteOpenHelper {
private Context context;
private static final String DATABASE_NAME = "Database.db";
private static final int DATABASE_VERSION = 1;
// Create table
private static final String TABLE_TEMP = "TEMPP";
private static final String COLUMN_ID = "id";
private static final String COLUMN_NAME = "name";
private static final String COLUMN_AGE = "age";
public DBHelper(@Nullable Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.context = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
String profileQuery = "CREATE TABLE " + TABLE_TEMP +
" (" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
COLUMN_NAME + " TEXT, " + COLUMN_AGE + " INTEGER " + ")";
db.execSQL(profileQuery);
}
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_TEMP);
onCreate(db);

}
// Functions for TEMP TABLE ********************************************************************************************************************************************  PROFILE TEMP
public Boolean insertData(String name, String age) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(COLUMN_NAME, name);
cv.put(COLUMN_AGE, age);
long result = db.insert(TABLE_TEMP, null, cv);
if (result == -1) {
Toast.makeText(context, "Failed to Insert", Toast.LENGTH_SHORT).show();
return  false;
} else {
Toast.makeText(context, "Data Inserted Successfully!", Toast.LENGTH_SHORT).show();
return true;
}
}
Cursor readData() {
String query = "SELECT * FROM " + TABLE_TEMP;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = null;
if (db != null) {
cursor = db.rawQuery(query, null);
}
return cursor;
}
// Update data using where clause;
public Boolean updateData(String row_id, String name, String age)
{
SQLiteDatabase db = this.getWritableDatabase(); // SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(COLUMN_NAME, name);
cv.put(COLUMN_AGE, age);
long result = db.update(TABLE_TEMP, cv, COLUMN_ID + " =? ", new String[]{row_id});

if (result == -1)
{
Toast.makeText(context, "Failed to Update",  Toast.LENGTH_SHORT).show();
return false;
}
else
{
Toast.makeText(context, "Successfully Updated!",  Toast.LENGTH_SHORT).show();
return true;
}
}

}

这是适配器

package com.example.insert_update_activity;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class myAdapter extends RecyclerView.Adapter<myAdapter.MyViewHolder> {
private Context context;
Activity activity;
private ArrayList id, name, age;
myAdapter(Activity activity, Context context, ArrayList id, ArrayList name, ArrayList age) {
this.activity = activity;
this.context = context;
this.id = id;
this.name = name;
this.age = age;
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.my_row, parent, false);
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, final int position) {
holder.id_txt.setText(String.valueOf(id.get(position)));
holder.name_txt.setText(String.valueOf(name.get(position)));
holder.age_txt.setText(String.valueOf(age.get(position)));
holder.mainLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(context, Update_Activity.class);
intent.putExtra("id", String.valueOf(id.get(position)));
intent.putExtra("name", String.valueOf(name.get(position)));
intent.putExtra("age", String.valueOf(age.get(position)));
activity.startActivityForResult(intent, 1);
}
});
}
@Override
public int getItemCount() {
return id.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView id_txt, name_txt, age_txt;
LinearLayout mainLayout;
public MyViewHolder(@NonNull View itemView) {
super(itemView);
id_txt = itemView.findViewById(R.id.id_txt);
name_txt = itemView.findViewById(R.id.name_txt);
age_txt = itemView.findViewById(R.id.age_txt);
mainLayout = itemView.findViewById(R.id.mainLayout);
}
}
}

这是recyclerView 的xml文件my_row

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:id="@+id/mainLayout">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:outlineSpotShadowColor="#000000"
app:cardElevation="3dp">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="12dp">
<TextView
android:id="@+id/id_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:text="1"
android:textColor="#9A9797"
android:textSize="35dp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/nameTitle"
android:layout_width="90dp"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="10dp"
android:text="NAME:"
android:textColor="#000"
android:textSize="16sp"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/ageTitle"
android:layout_width="90dp"
android:layout_height="wrap_content"
android:text="AGE:"
android:textColor="#000"
android:textSize="16sp"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="@+id/nameTitle"
app:layout_constraintTop_toBottomOf="@+id/nameTitle" />
<TextView
android:id="@+id/name_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Name"
android:textSize="15sp"
app:layout_constraintStart_toEndOf="@+id/nameTitle"
app:layout_constraintTop_toTopOf="@+id/nameTitle" />
<TextView
android:id="@+id/age_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Age"
android:textSize="15sp"
app:layout_constraintStart_toEndOf="@+id/ageTitle"
app:layout_constraintTop_toBottomOf="@+id/nameTitle" />

</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
</LinearLayout>

登录活动非常简单。它只允许用户在username＝"的情况下登录；用户1"；并且密码=="；123456"；。CreateProfile_Activity只使用insertData一次

Answer 1

好了，现在可以工作了。我不确定这是为什么，但我会发布我所做的更改。

所以myAdapter出现了一个问题。在主布局中单击"；name"；以及"；年龄；其中不同于"；名称"；以及"；年龄；在从Intent获取数据的UpdateActivity中。"age"one_answers"name"的第一个字母都不是大写的。我改变的另一件事是onBindHolder中的get(位置(。

现在onBindHolder看起来是这样的：

public void onBindViewHolder(@NonNull MyViewHolder holder, final int position) {
holder.id_txt.setText(String.valueOf(id.get(holder.getAdapterPosition())));
holder.name_txt.setText(String.valueOf(name.get(holder.getAdapterPosition())));
holder.age_txt.setText(String.valueOf(age.get(holder.getAdapterPosition())));

holder.mainLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), Update_Activity.class);
intent.putExtra("id", String.valueOf(id.get(holder.getAdapterPosition())));
intent.putExtra("Name", String.valueOf(name.get(holder.getAdapterPosition())));
intent.putExtra("Age", String.valueOf(age.get(holder.getAdapterPosition())));
v.getContext().startActivity(intent);
//activity.startActivityForResult(intent, 1);
}
});
}

希望它能帮助任何