- Adapter是UI控件和实际数据之间的桥梁,通过adapter将数据展示到UI上
- Adapter本身只是一个接口，Adapter及其子类的继承关系图
- Adapter常用的实现类如下。
- ArrayAdapter: 简单、易用的Adapter。通常用于将数组或List集合的多个值包装成多个列表项。
- SimpleAdapter: 并不简单、功能强大的Adapter.可用于将List集合的多个对象包装成多个列表项。
- SimpleCursorAdapter: 与SimpleAdapter基本相似，只是用于包装Cursor提供的数据。
- BaseAdapter: 通常用于被扩展。扩展BaseAdapter可以对各列表项进行最大限度的定制。
- AdapterView是常用的安卓UI控件
- AdapterView继承了ViewGroup.它的本质是容器。
- AdapterView显示的多个“列表项”由Adapter提供。调用AdapterView的**setAdapter(Adapter)**方法设置Adapter即可
- Adapter是UI控件和实际数据之间的桥梁,通过adapter将数据展示到UI上
- AdapterView是一个抽象类, 具体继承关系如下
- 常用的实体类为第四行, 注意Gallery已经被淘汰, 可以用HorizontalScrollView
- ListView也可用RecyclerView替代
定义一个item布局文件(list中的每一项) – list_item.xml
<?xml version="1.0" encoding="UTF-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textSize="24sp"
android:id = "@+id/listItem"
>
</TextView>
定义一个listView布局文件 – list_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/myList"/>
</LinearLayout>
*
使用Adapter
package com.example.homework2;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.graphics.Point;
import android.os.Bundle;
import android.view.Display;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list_view);
Display display = getWindowManager().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
int height = size.y;
String[] items = new String[]{"Apple", "Mongo", "Pear", "Grape", "Banana", "Strawberry", "Blackberry", "Raspberry", "Peach", "Watermelon", "Cherry", "DragonFruit"};
final ArrayList<String> list = new ArrayList<>();
for (int i = 0; i < items.length; i++) {
list.add(items[i]);
}
ListView listview = findViewById(R.id.myList);
listview.setAdapter(new ArrayAdapter<String>(this, R.layout.list_item, list) {
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = super.getView(position, convertView, parent);
TextView textView = (view.findViewById(R.id.listItem));
textView.setMinHeight(0);
textView.setMinimumHeight(0);
textView.setHeight(height/ items.length);
return view;
}
});
}
输出结果
定义一个listView布局文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center">
<ListView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/lv1"
android:drawSelectorOnTop="true" />
</LinearLayout>
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版权声明：本文为CSDN博主「0x2015」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/w57685321/article/details/78267051
**定义一个item布局文件(list中的每一项) **
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/img"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingStart="10dp"
android:adjustViewBounds="true"
android:maxWidth="100dp"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/author"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>
————————————————
版权声明：本文为CSDN博主「0x2015」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/w57685321/article/details/78267051
创建一个Simple Adapter, 将数据绑定到UI
package com.example.admin.test3;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Test2Activity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test2);
//获取布局中的ListView
final ListView lv1 = (ListView)findViewById(R.id.lv1);
//获取图片资源文件
int [] images = new int[]{R.drawable.img4,R.drawable.img5,R.drawable.img6,R.drawable.img7};
String []title = new String[]{"实战大数据——","白话深度学习与","Unity 3D\\2D手机游戏开发：从学习","Web前端自动化构"};
String []author = new String[]{"许国根，贾瑛","高扬","金玺曾","[澳]斯特凡·鲍姆加"};
//将上面的数据添加到List集合中
List<Map<String,Object>> listItems = new ArrayList<Map<String,Object>>();
for(int i=0;i<title.length;i++){
//每一行数据都是一个Object，然后存入Map中，String自己指定
Map<String,Object> map = new HashMap<String,Object>();
map.put("img",images[i]);
map.put("title",title[i]);
map.put("author",author[i]);
listItems.add(map);
}
//关键的SimpleAdapter
/* 关于SimpleAdapter，使用SimpleAdapter的最大难点在于创建SimpleAdapter对象，它需要5个参数：
>* 第一个参数：上下文，这个不用多说，写this即可。
>* 第二个参数：该参数应该是一个 List< Map> 类型的集合对象，该集合中每个Map<String>对象生成一个列表项。
>* 第三个参数：该参数指定一个界面布局的ID，这里使用的自己创建的xml布局文件。
>* 第四个参数：该参数是一个String[]类型的参数，该参数决定提取Map对象中哪些key对应的value来生成列表项，所以填写map.put(key,Value)对应的key即可。
>* 第五个参数：该参数是一个int[]类型的参数，该参数决定填充哪些组件，填写自定义的xml布局文件中控件的ID即可，相当于把第四个参数指定的数据填充到第五个控件指定的控件中，与第四个参数形成对应关系*/
SimpleAdapter adapter = new SimpleAdapter(
this,
listItems,
R.layout.simpleadaitem,
new String[]{"img","title","author"},
new int[]{R.id.img,R.id.title, R.id.author});
lv1.setAdapter(adapter);
}
}
————————————————
版权声明：本文为CSDN博主「0x2015」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/w57685321/article/details/78267051
OnItemClickListener – 可以处理视图中单个条目的点击事件
listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String selectedItem = (String) parent.getItemAtPosition(position);
Intent intent = new Intent(view.getContext(), WebActivity.class);
intent.putExtra("item_name", selectedItem);
startActivity (intent);
}
});
OnScrollListener – ListView的滚动事件，监听滚动事件，可以做到下拉刷新，下拉显示更多列表的操作
lv1.setOnScrollListener(new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView absListView, int i) {
switch(i){
case SCROLL_STATE_FLING:
Log.i("Main", "用户在手指离开屏幕之前，由于用力滑了一下，视图仍在滚动");
break;
case SCROLL_STATE_IDLE:
Log.i("Main", "视图已经停止滚动");
break;
case SCROLL_STATE_TOUCH_SCROLL:
Log.i("Main", "手指没有离开屏幕，视图正在滑动");
break;
}
}
@Override
public void onScroll(AbsListView absListView, int i, int i1, int i2) {
}
});
————————————————
版权声明：本文为CSDN博主「0x2015」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/w57685321/article/details/78267051
ExpandableListView
创建一个GridView布局文件
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
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"
tools:context=".MainActivity">
<!-- android:numColumns=2 is the number of columns for Grid View
android:horizontalSpacing is the space between horizontal
grid items.-->
<GridView
android:id="@+id/idGVcourses"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:horizontalSpacing="6dp"
android:numColumns="2"
android:verticalSpacing="6dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
创建每个item的布局文件
<?xml version="1.0" encoding="utf-8"?>
<!--XML implementation of Card Layout-->
<androidx.cardview.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="120dp"
android:layout_gravity="center"
android:layout_margin="5dp"
app:cardCornerRadius="5dp"
app:cardElevation="5dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:id="@+id/idIVcourse"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_gravity="center"
android:src="@mipmap/ic_launcher" />
<TextView
android:id="@+id/idTVCourse"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/app_name"
android:textAlignment="center" />
</LinearLayout>
</androidx.cardview.widget.CardView>
创建一个Modal类用来储存数据
public class CourseModel {
// string course_name for storing course_name
// and imgid for storing image id.
private String course_name;
private int imgid;
public CourseModel(String course_name, int imgid) {
this.course_name = course_name;
this.imgid = imgid;
}
public String getCourse_name() {
return course_name;
}
public void setCourse_name(String course_name) {
this.course_name = course_name;
}
public int getImgid() {
return imgid;
}
public void setImgid(int imgid) {
this.imgid = imgid;
}
}
创建一个Adapter, extend ArrayAdapter
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import java.util.ArrayList;
public class CourseGVAdapter extends ArrayAdapter<CourseModel> {
public CourseGVAdapter(@NonNull Context context, ArrayList<CourseModel> courseModelArrayList) {
super(context, 0, courseModelArrayList);
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
View listitemView = convertView;
if (listitemView == null) {
// Layout Inflater inflates each item to be displayed in GridView.
listitemView = LayoutInflater.from(getContext()).inflate(R.layout.card_item, parent, false);
}
CourseModel courseModel = getItem(position);
TextView courseTV = listitemView.findViewById(R.id.idTVCourse);
ImageView courseIV = listitemView.findViewById(R.id.idIVcourse);
courseTV.setText(courseModel.getCourse_name());
courseIV.setImageResource(courseModel.getImgid());
return listitemView;
}
}
使用Adapter
import android.os.Bundle;
import android.widget.GridView;
import androidx.appcompat.app.AppCompatActivity;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
GridView coursesGV;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
coursesGV = findViewById(R.id.idGVcourses);
ArrayList<CourseModel> courseModelArrayList = new ArrayList<CourseModel>();
courseModelArrayList.add(new CourseModel("DSA", R.drawable.ic_gfglogo));
courseModelArrayList.add(new CourseModel("JAVA", R.drawable.ic_gfglogo));
courseModelArrayList.add(new CourseModel("C++", R.drawable.ic_gfglogo));
courseModelArrayList.add(new CourseModel("Python", R.drawable.ic_gfglogo));
courseModelArrayList.add(new CourseModel("Javascript", R.drawable.ic_gfglogo));
courseModelArrayList.add(new CourseModel("DSA", R.drawable.ic_gfglogo));
CourseGVAdapter adapter = new CourseGVAdapter(this, courseModelArrayList);
coursesGV.setAdapter(adapter);
}
}
创建布局文件
<?xml version="1.0" encoding="utf-8"?>
<!--Constraint layout which contain Spinner widget-->
<android.support.constraint.ConstraintLayout
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="match_parent"
tools:context="com.geeksforgeeks.Spinner.MainActivity">
<!--Spinner widget-->
<Spinner
android:id="@+id/coursesspinner"
android:layout_height="50dp"
android:layout_width="160dp"
android:layout_marginEnd="10dp"
android:layout_marginStart="10dp"
android:layout_marginBottom="10dp"
android:layout_marginTop="10dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
</android.support.constraint.ConstraintLayout>
创建Java文件
import android.support.v7.app.AppCompatActivity;
import android.widget.AdapterView;
import android.view.View;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.os.Bundle;
// Main Activity implements Adapter view
public class MainActivity
extends AppCompatActivity
implements AdapterView.OnItemSelectedListener {
// create array of Strings
// and store name of courses
String[] courses = { "C", "Data structures",
"Interview prep", "Algorithms",
"DSA with java", "OS" };
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Take the instance of Spinner and
// apply OnItemSelectedListener on it which
// tells which item of spinner is clicked
Spinner spino = findViewById(R.id.coursesspinner);
spin.setOnItemSelectedListener(this);
// Create the instance of ArrayAdapter
// having the list of courses
ArrayAdapter ad = new ArrayAdapter(
this,
android.R.layout.simple_spinner_item,
courses);
// set simple layout resource file
// for each item of spinner, a simple text view
ad.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spino.setAdapter(ad);
}
// Performing action when ItemSelected
// from spinner, Overriding onItemSelected method
@Override
public void onItemSelected(AdapterView<*> arg0, View arg1, int position, long id) {
// make toastof name of course
Toast.makeText(getApplicationContext(), courses[position], Toast.LENGTH_LONG).show();
}
@Override
public void onNothingSelected(AdapterView<*> arg0)
{
// Auto-generated method stub
}
}
- AdapterViewFlipper可以实现画面自动播放
- SatckView可以实现叠加效果
