有人能解释或建议一个教程，动态创建一个ListView在android?
以下是我的要求:
我应该能够通过按下按钮动态添加新元素。 应该足够简单易懂(例如，可能没有任何性能改进或convertView)
我知道关于这个话题有很多问题，但我找不到任何一个能回答我的问题。
当前回答
java文件的代码。
public class MainActivity extends Activity {
ListView listview;
Button Addbutton;
EditText GetValue;
String[] ListElements = new String[] {
"Android",
"PHP"
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listview = (ListView) findViewById(R.id.listView1);
Addbutton = (Button) findViewById(R.id.button1);
GetValue = (EditText) findViewById(R.id.editText1);
final List < String > ListElementsArrayList = new ArrayList < String >
(Arrays.asList(ListElements));
final ArrayAdapter < String > adapter = new ArrayAdapter < String >
(MainActivity.this, android.R.layout.simple_list_item_1,
ListElementsArrayList);
listview.setAdapter(adapter);
Addbutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ListElementsArrayList.add(GetValue.getText().toString());
adapter.notifyDataSetChanged();
}
});
}
}
activity_main.xml布局文件的代码。
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.listviewaddelementsdynamically_android_examples
.com.MainActivity" >
<Button
android:id="@+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/editText1"
android:layout_centerHorizontal="true"
android:text="ADD Values to listview" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="26dp"
android:ems="10"
android:hint="Add elements listView" />
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/button1"
android:layout_centerHorizontal="true" >
</ListView>
</RelativeLayout>
截图
其他回答
而不是
listItems.add("New Item");
adapter.notifyDataSetChanged();
您可以直接拨打
adapter.add("New Item");
java文件的代码。
public class MainActivity extends Activity {
ListView listview;
Button Addbutton;
EditText GetValue;
String[] ListElements = new String[] {
"Android",
"PHP"
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listview = (ListView) findViewById(R.id.listView1);
Addbutton = (Button) findViewById(R.id.button1);
GetValue = (EditText) findViewById(R.id.editText1);
final List < String > ListElementsArrayList = new ArrayList < String >
(Arrays.asList(ListElements));
final ArrayAdapter < String > adapter = new ArrayAdapter < String >
(MainActivity.this, android.R.layout.simple_list_item_1,
ListElementsArrayList);
listview.setAdapter(adapter);
Addbutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ListElementsArrayList.add(GetValue.getText().toString());
adapter.notifyDataSetChanged();
}
});
}
}
activity_main.xml布局文件的代码。
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.listviewaddelementsdynamically_android_examples
.com.MainActivity" >
<Button
android:id="@+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/editText1"
android:layout_centerHorizontal="true"
android:text="ADD Values to listview" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="26dp"
android:ems="10"
android:hint="Add elements listView" />
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/button1"
android:layout_centerHorizontal="true" >
</ListView>
</RelativeLayout>
截图
如果你想让ListView在AppCompatActivity而不是ListActivity中，你可以做以下事情(修改@Shardul的答案):
public class ListViewDemoActivity extends AppCompatActivity {
//LIST OF ARRAY STRINGS WHICH WILL SERVE AS LIST ITEMS
ArrayList<String> listItems=new ArrayList<String>();
//DEFINING A STRING ADAPTER WHICH WILL HANDLE THE DATA OF THE LISTVIEW
ArrayAdapter<String> adapter;
//RECORDING HOW MANY TIMES THE BUTTON HAS BEEN CLICKED
int clickCounter=0;
private ListView mListView;
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.activity_list_view_demo);
if (mListView == null) {
mListView = (ListView) findViewById(R.id.listDemo);
}
adapter=new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
listItems);
setListAdapter(adapter);
}
//METHOD WHICH WILL HANDLE DYNAMIC INSERTION
public void addItems(View v) {
listItems.add("Clicked : "+clickCounter++);
adapter.notifyDataSetChanged();
}
protected ListView getListView() {
if (mListView == null) {
mListView = (ListView) findViewById(R.id.listDemo);
}
return mListView;
}
protected void setListAdapter(ListAdapter adapter) {
getListView().setAdapter(adapter);
}
protected ListAdapter getListAdapter() {
ListAdapter adapter = getListView().getAdapter();
if (adapter instanceof HeaderViewListAdapter) {
return ((HeaderViewListAdapter)adapter).getWrappedAdapter();
} else {
return adapter;
}
}
}
在你的布局，而不是使用android:id="@android:id/列表"，你可以使用android:id="@+id/listDemo"
现在你可以在普通的AppCompatActivity中有一个ListView。
This is the simple answer how to add datas dynamically in listview android kotlin
class MainActivity : AppCompatActivity(){
var listItems = arrayListOf<String>()
val array = arrayOf("a","b","c","d","e")
var listView: ListView? = null
private lateinit var adapter: listViewAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.scrollview_layout)
listItems.add("a")
listItems.add("b")
listItems.add("c")
listItems.add("d")
listItems.add("e")
//if you want to add array items to a list you can try this for each loop
for(items in array)
listItems.add(items)
//check the result in console
Log.e("TAG","listItems array: $listItems")
adapter = ListViewAdapter()
adapter.updateList(listItems)
adapter.notifyDataSetChanged()
}
}
//Here is the adapter class
class ListviewAdapter : BaseAdapter(){
private var itemsList = arrayListOf<String>()
override fun getView(position: Int, container: View?, parent: ViewGroup?): View {
var view = container
val inflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
if (view == null)
view = inflater.inflate(R.layout.list_pc_summary, parent, false)
return view
}
override fun getItem(position: Int): Any = itemsList[position]
override fun getItemId(position: Int): Long = position.toLong()
override fun getCount(): Int = itemsList.size
fun updateList(listItems: ArrayList<String>()){
this.itemsList = listItems
notifyDatSetChanged
}
}
//Here I just explained two ways, we can do this many ways.
首先在项目的res/layout/main.xml文件夹中创建一个XML布局:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<Button
android:id="@+id/addBtn"
android:text="Add New Item"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="addItems"/>
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:drawSelectorOnTop="false"
/>
</LinearLayout>
这是一个简单的布局，顶部有一个按钮，底部有一个列表视图。注意，ListView有id @android:id/list，它定义了ListActivity可以使用的默认ListView。
public class ListViewDemo extends ListActivity {
//LIST OF ARRAY STRINGS WHICH WILL SERVE AS LIST ITEMS
ArrayList<String> listItems=new ArrayList<String>();
//DEFINING A STRING ADAPTER WHICH WILL HANDLE THE DATA OF THE LISTVIEW
ArrayAdapter<String> adapter;
//RECORDING HOW MANY TIMES THE BUTTON HAS BEEN CLICKED
int clickCounter=0;
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
adapter=new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,
listItems);
setListAdapter(adapter);
}
//METHOD WHICH WILL HANDLE DYNAMIC INSERTION
public void addItems(View v) {
listItems.add("Clicked : "+clickCounter++);
adapter.notifyDataSetChanged();
}
}
android.R.layout。simple_list_item_1是Android提供的默认列表项布局，你可以使用这个库存布局来处理不复杂的事情。
listItems是一个列表，它包含ListView中显示的数据。所有的插入和删除都应该在listItems上完成;listItems中的变化应该反映在视图中。这是由ArrayAdapter<String>适配器处理的，它应该被通知使用:
adapter.notifyDataSetChanged ();
一个Adapter是用3个参数实例化的:context，它可以是activity/listactivity;个人列表项的布局;最后是列表，它是列表中显示的实际数据。
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