两个活动之间的共享数组列表不起作用
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【中文标题】两个活动之间的共享数组列表不起作用【英文标题】：Shared arraylist between two activity doesn't work 【发布时间】：2018-12-29 03:36:33 【问题描述】：我有一个问题，当我在复选框中选择我的项目时（因此它被选中），数组已填充，但是当我单击“完成”时，称为新活动 GenreViewActivity，它调用了获取数组列表的方法之前的activity，但是它的ListView，布局是空的。我错了什么？
AccountActivity GenreViewActivity
AccountActivity.java：
package com.example.msnma.movienotifier;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.res.TypedArray;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class AccountActivity extends AppCompatActivity
private static ArrayList <String> itemsChkStr = new ArrayList<String();
public class Item
boolean checked;
Drawable ItemDrawable;
String ItemString;
Item(/*Drawable drawable,*/ String t, boolean b)
//ItemDrawable = drawable;
ItemString = t;
checked = b;
public boolean isChecked()
return checked;
static class ViewHolder
CheckBox checkBox;
ImageView icon;
TextView text;
public class ItemsListAdapter extends BaseAdapter
private Context context;
private List<Item> list;
ItemsListAdapter(Context c, List<Item> l)
context = c;
list = l;
@Override
public int getCount()
return list.size();
@Override
public Object getItem(int position)
return list.get(position);
@Override
public long getItemId(int position)
return position;
public boolean isChecked(int position)
return list.get(position).checked;
@Override
public View getView(final int position, View convertView, ViewGroup parent)
View rowView = convertView;
// reuse views
ViewHolder viewHolder = new ViewHolder();
if (rowView == null)
LayoutInflater inflater = ((Activity)
context).getLayoutInflater();
rowView = inflater.inflate(R.layout.row, null);
viewHolder.checkBox = (CheckBox)
rowView.findViewById(R.id.rowCheckBox);
//viewHolder.icon = (ImageView)
rowView.findViewById(R.id.rowImageView);
viewHolder.text = (TextView)
rowView.findViewById(R.id.rowTextView);
rowView.setTag(viewHolder);
else
viewHolder = (ViewHolder) rowView.getTag();
//viewHolder.icon.setImageDrawable(list.get(position).ItemDrawable);
viewHolder.checkBox.setChecked(list.get(position).checked);
final String itemStr = list.get(position).ItemString;
viewHolder.text.setText(itemStr);
viewHolder.checkBox.setTag(position);
/*
viewHolder.checkBox.setOnCheckedChangeListener(
new CompoundButton.OnCheckedChangeListener()
@Override
public void onCheckedChanged(CompoundButton
compoundButton, boolean b)
list.get(position).checked = b;
Toast.makeText(getApplicationContext(),
itemStr + "onCheckedChanged\nchecked: " + b,
Toast.LENGTH_LONG).show();
);
*/
viewHolder.checkBox.setOnClickListener(new
View.OnClickListener()
@Override
public void onClick(View view)
boolean newState = !list.get(position).isChecked();
list.get(position).checked = newState;
Toast.makeText(getApplicationContext(),
itemStr + "setOnClickListener\nchecked: " + newState,
Toast.LENGTH_LONG).show();
);
viewHolder.checkBox.setChecked(isChecked(position));
return rowView;
Button btnLookup;
Button btnDone;
List<Item> items;
ListView listView;
ItemsListAdapter myItemsListAdapter;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_account);
listView = (ListView)findViewById(R.id.listview);
btnLookup = (Button)findViewById(R.id.lookup);
btnDone = (Button) findViewById(R.id.done);
initItems();
myItemsListAdapter = new ItemsListAdapter(this, items);
listView.setAdapter(myItemsListAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener()
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id)
Toast.makeText(AccountActivity.this,
((Item)(parent.getItemAtPosition(position))).ItemString,
Toast.LENGTH_LONG).show();
);
//Arraylist di tipo stringa con elementi checked
for (int i=0; i<items.size(); i++)
if (items.get(i).isChecked())
//str += i + "\n";
itemsChkStr.add(items.get(i).ItemString);
btnLookup.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
String str = "Check items:\n";
for (int i=0; i<items.size(); i++)
if (items.get(i).isChecked())
//str += i + "\n";
str += items.get(i).ItemString;
/*
int cnt = myItemsListAdapter.getCount();
for (int i=0; i<cnt; i++)
if(myItemsListAdapter.isChecked(i))
str += i + "\n";
*/
Toast.makeText(AccountActivity.this,
str,
Toast.LENGTH_LONG).show();
);
private void initItems()
items = new ArrayList<Item>();
TypedArray arrayDrawable = getResources().obtainTypedArray(R.array.resicon);
TypedArray arrayText = getResources().obtainTypedArray(R.array.restext);
for(int i=0; i<arrayDrawable.length(); i++)
//Drawable d = arrayDrawable.getDrawable(i);
String s = arrayText.getString(i);
boolean b = false;
Item item = new Item(/*d,*/ s, b);
items.add(item);
arrayDrawable.recycle();
arrayText.recycle();
public void pressDoneButton(View view)
//itemsChecks();
Intent intent = new Intent(this, GenreViewActivity.class);
//EditText editText = (EditText) findViewById(R.id.editText);
//String message = editText.getText().toString();
//intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
/*public ArrayList <String> itemsChecks()
ArrayList <String> arrGenre = new ArrayList<String>();
for (int i=0; i<items.size(); i++)
if (items.get(i).isChecked())
arrGenre.add(items.get(i).toString());
viewArray(arrGenre);
*/
public static ArrayList <String> getSelectedString()
return itemsChkStr;
/*@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_account);
Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
setSupportActionBar(myToolbar);
// Get a support ActionBar corresponding to this toolbar
ActionBar ab = getSupportActionBar();
// Enable the Up button
ab.setDisplayHomeAsUpEnabled(true);
public boolean onCreateOptionsMenu(Menu menu)
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_second, 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;
return super.onOptionsItemSelected(item);
public void pressAccountButton(MenuItem item)
Intent intent = new Intent(this, AccountActivity.class);
//EditText editText = (EditText) findViewById(R.id.editText);
//String message = editText.getText().toString();
//intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
*/
GenreViewActivity：
package com.example.msnma.movienotifier;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.List;
public class GenreViewActivity extends AppCompatActivity
//AccountActivity aa = new AccountActivity();
private ListView lv;
@Override
public void onCreate(Bundle saveInstanceState)
super.onCreate(saveInstanceState);
setContentView(R.layout.activity_genre_view);
lv = findViewById(R.id.listview);
// Instanciating an array list (you don't need to do this,
// you already have yours).
ArrayList<String> your_array_list; //= new ArrayList<String>();
/*your_array_list.add("foo");
your_array_list.add("bar");*/
your_array_list = AccountActivity.getSelectedString();
// This is the array adapter, it takes the context of the activity as a
// first parameter, the type of list view as a second parameter and your
// array as a third parameter.
ArrayAdapter<String> arrayAdapter1 = new ArrayAdapter<String>(
this,
android.R.layout.simple_list_item_1,
your_array_list);
lv.setAdapter(arrayAdapter1);
/*@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_genre_view);
*/
activity_genre_view.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
android:orientation="vertical"
tools:context=".GenreViewActivity">
<TextView
android:layout_
android:layout_
android:layout_gravity="center_horizontal"
android:text="Genre"
android:textStyle="bold" />
<!--android:autoLink="web"-->
<ListView
android:id="@+id/listview"
android:layout_
android:layout_ />
</LinearLayout>
【问题讨论】：
你能清理一下你的代码吗？删除注释掉的代码 @user47845 你需要在checkBox.setOnClickListener Method下面添加这行itemsChkStr.add(list.get(position).ItemString);。
【参考方案1】：
使用putStringArrayListExtra来传递ArrayList。
public void pressDoneButton(View view)
//itemsChecks();
Intent intent = new Intent(this, GenreViewActivity.class);
intent.putStringArrayListExtra("your_list",itemsChkStr);
startActivity(intent);
并使用intent.getStringArrayListExtra("your_list"); 获取ArrayList。
在您的 GenreViewActivity...
if(getIntent()!=null)
your_array_list = getIntent().getStringArrayListExtra("your_list");
【讨论】：
真的是:)【参考方案2】：当然会是空的。您仅在开始之前填充静态数组 itemsChkStr，然后您尝试进行检查。您需要在每次检查操作后更新您的静态检查列表。
【讨论】：
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