android - 将文本打印到列表视图,从对话框输入
问题描述
我有关于代码的情况。我找不到解决方案,因为我是这方面的初学者。
我有 3 个片段,每个片段都有列表视图的框架。你可以在这里查看面板。
我有一个导航菜单,上面有一个“添加任务”按钮。此按钮打开一个对话框,当我单击“确定”时,对话框需要一个文本(问题从这里开始)写入“todotasks_frame.xml”中的列表视图(id = listview1)。但我做不到。
我的 MainActivity 代码
package com.example.lenovo.myapplication;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
ArrayList<String> todotasks_frame,completedtasks_frame,alltasks_frame;
ArrayAdapter<String> todotasks_frameAdapter,completedtasks_frameAdapter,alltasks_frameAdapter;
AlertDialog dialog;
AlertDialog.Builder builder;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
FragmentToDoTasks fragmentToDoTasks=new FragmentToDoTasks();
ft.add(R.id.content_frame,fragmentToDoTasks);
ft.commit();
todotasks_frame=new ArrayList<>();
todotasks_frameAdapter = new ArrayAdapter<>(this, R.layout.simplerow, todotasks_frame);
completedtasks_frame=new ArrayList<>();
completedtasks_frameAdapter =new ArrayAdapter<>(this, R.layout.simplerow, completedtasks_frame);
alltasks_frame=new ArrayList<>();
alltasks_frameAdapter =new ArrayAdapter<>(this, R.layout.simplerow, alltasks_frame);
builder = new AlertDialog.Builder(this);
builder.setTitle("Add a Task");
final EditText input = new EditText(this);
builder.setView(input);
builder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which){
/* Problem area :,( */
}
});
builder.setNegativeButton(android.R.string.cancel,new DialogInterface.OnClickListener(){
@Override
public void onClick(DialogInterface dialog, int which){
dialog.dismiss();
}
});
dialog=builder.create();
}
@Override
public void onBackPressed() {
DrawerLayout drawer = findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
int id = item.getItemId();
if (id == R.id.main_todo_tasks) {
FragmentToDoTasks fragmentToDoTasks = new FragmentToDoTasks();
ft.replace(R.id.content_frame, fragmentToDoTasks);
ft.commit();
} else if (id == R.id.main_completed_tasks) {
FragmentCompletedTasks fragmentCompletedTasks = new FragmentCompletedTasks();
ft.replace(R.id.content_frame, fragmentCompletedTasks);
ft.commit();
} else if (id == R.id.main_all_tasks) {
FragmentAllTasks fragmentAllTasks = new FragmentAllTasks();
ft.replace(R.id.content_frame, fragmentAllTasks);
ft.commit();
} else if (id == R.id.main_close) super.onBackPressed();
return true;
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
int id = item.getItemId();
if (id == R.id.nav_add_tasks) {
dialog.show();
} else if (id == R.id.nav_todo_tasks) {
FragmentToDoTasks fragmentToDoTasks = new FragmentToDoTasks();
ft.replace(R.id.content_frame, fragmentToDoTasks);
ft.commit();
} else if (id == R.id.nav_completed_tasks) {
FragmentCompletedTasks fragmentCompletedTasks = new FragmentCompletedTasks();
ft.replace(R.id.content_frame, fragmentCompletedTasks);
ft.commit();
} else if (id == R.id.nav_all_tasks) {
FragmentAllTasks fragmentAllTasks = new FragmentAllTasks();
ft.replace(R.id.content_frame, fragmentAllTasks);
ft.commit();
} else if (id == R.id.nav_exit) super.onBackPressed();
DrawerLayout drawer = findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
解决方案
考虑到您的问题,我创建了一个演示项目我所做的是我创建了 10 个虚拟项目的回收器视图,之后当您添加新任务时,有一个添加新任务的按钮,它很容易添加到列表中并且列表得到轻松更新新条目。YOUR_LIST_NAME.clear()
成功的关键是除了onCreate()
方法之外不要在任何地方使用
希望此代码将帮助您理解notifyDataSetChanged();
调用它的值,studentAdapter
它只是使用列表中所做的更改来更新列表,例如从列表中添加、删除。
NewMainActivity.class
public class NewMainActivity extends AppCompatActivity {
RecyclerView recycle;
StudentAdapter studentAdapter;
Button addNewButton;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_new);
recycle = findViewById(R.id.recycle);
addNewButton = findViewById(R.id.addNewButton);
setListeners();
listing.clear();
produceList();
}
AlertDialog.Builder builder;
ArrayList<StudentModel> listing = new ArrayList<>();
private void produceList() {
for (int k = 0; k < 10; k++) {
StudentModel studentModel = new StudentModel();
studentModel.setName(k + " Task");
listing.add(studentModel);
}
Collections.reverse(listing);
studentAdapter = new StudentAdapter(NewMainActivity.this, listing);
recycle.setNestedScrollingEnabled(false);
recycle.setLayoutManager(new LinearLayoutManager(this));
recycle.setAdapter(studentAdapter);
studentAdapter.notifyDataSetChanged();
}
public void setListeners() {
addNewButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
builder = new AlertDialog.Builder(NewMainActivity.this);
builder.setTitle("Add a Task");
final EditText input = new EditText(NewMainActivity.this);
builder.setView(input);
builder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
String name = input.getText().toString();
StudentModel studentModel = new StudentModel();
studentModel.setName(name);
listing.add(studentModel);
Collections.reverse(listing);
studentAdapter.notifyDataSetChanged();
}
});
builder.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
}).show();
}
});
}
}
activity_main_new.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/addNewButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Add New" />
<android.support.v7.widget.RecyclerView
android:id="@+id/recycle"
android:layout_width="match_parent"
android:layout_height="match_parent" />
回收者视图适配器的单个项目
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="20dp"
android:text="name" />
StudentAdapter.class
public class StudentAdapter extends RecyclerView.Adapter<StudentAdapter.MyViewHolder> {
ArrayList<?> notificationListData;
Context context;
public StudentAdapter(Context context, ArrayList<?> notificationListData) {
this.context = context;
this.notificationListData = notificationListData;
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_studenyt, parent, false);
return new MyViewHolder(v);
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
if (notificationListData.get(position) instanceof StudentModel) {
holder.name.setText(((StudentModel) notificationListData.get(position)).getName());
}
}
@Override
public int getItemCount() {
return notificationListData.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView name;
public MyViewHolder(View itemView) {
super(itemView);
name = itemView.findViewById(R.id.name);
}
}
}
StudentModel.class
public class StudentModel {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}