十分之一代码写完安卓listview adapter 和xml
前言：
众所周知，安卓自定义一个自己想要的类的特定布局的listview的流程很复杂
首先需要在主xml里定义一个listview，新建xml画出单个list item的布局，新建一个物品类新建一个物品的adapter类，布置各种属性，在代码里初始化adapter，
这些步骤加起来代码估计已经上百行了，但其实只需要十分之一代码就能解决这个问题，只需要两步
物品类代码添加
传统示例：
主xml
<ListView
android:id="@+id/lv_menu"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
单个布局xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/lv_item_selector"
>
<TextView
android:id="@+id/animalName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_centerVertical="true"/>
<ImageView
android:id="@+id/animalImage"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_marginRight="20dp"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:scaleType="centerCrop"
/>
</RelativeLayout>
物品类
package com.eric.test1;
public class Animal {
public String name;
public int img;
public Animal(String name, int img) {
this.name = name;
this.img = img;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public int getImg() {
return img;
}
public void setImg(int img) {
this.img = img;
}
}
adapter类
package com.eric.test1;
import android.content.Context;
import android.text.Layout;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.constraintlayout.widget.ConstraintSet;
import org.w3c.dom.Text;
import java.util.List;
public class animalAdapter extends BaseAdapter {
public List<Animal> data;
private Context context;
public animalAdapter(List<Animal> data, Context context) {
this.data = data;
this.context = context;
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
if(convertView == null){
convertView = LayoutInflater.from(context).inflate(R.layout.animal_item,parent,false);
}
TextView textView = convertView.findViewById(R.id.animalName);
ImageView imageView = convertView.findViewById(R.id.animalImage);
textView.setText(data.get(position).getName());
imageView.setImageResource(data.get(position).getImg());
return convertView;
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int i) {
return null;
}
@Override
public long getItemId(int position) {
return position;
}
}
主java代码
package com.eric.test1;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.ActionMode;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class Hw3P4 extends AppCompatActivity {
private List<Animal> animals = new ArrayList<>();
public List toDel = new ArrayList();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_hw3_p4);
initAnimals();
animalAdapter animalAdapter = new animalAdapter(animals,this);
ListView listView = findViewById(R.id.lv_menu);
listView.setAdapter(animalAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Toast.makeText(getApplicationContext(),animals.get(i).getName(),Toast.LENGTH_SHORT).show();
}
});
listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE_MODAL);
listView.setMultiChoiceModeListener(new AbsListView.MultiChoiceModeListener() {
@Override
public void onItemCheckedStateChanged(ActionMode mode, int position, long id, boolean checked) {
if(checked){
// Toast.makeText(getApplicationContext(),position+"is checked",Toast.LENGTH_LONG).show();
toDel.add(String.valueOf(position));
}
else{
// Toast.makeText(getApplicationContext(),position+"is unchecked",Toast.LENGTH_LONG).show();
toDel.remove(String.valueOf(position));
}
}
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
mode.getMenuInflater().inflate(R.menu.dl_animal, menu);
return true;
}
@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
return false;
}
@Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item ) {
Collections.sort(toDel);
Log.e("list:","current list: "+ toDel);
for(int i = 0;i< toDel.size();i++){
animals.remove(Integer.parseInt(String.valueOf(toDel.get(i)))-i);
}
toDel.clear();
mode.finish();
Log.e("list:","After deleted: "+toDel);
return true;
}
@Override
public void onDestroyActionMode(ActionMode mode) {
}
});
}
private void initAnimals(){
Animal lion = new Animal("Lion",R.mipmap.lion);
Animal cat = new Animal("Cat",R.mipmap.cat);
Animal dog = new Animal("Dog",R.mipmap.dog);
Animal elephant = new Animal("Elephant",R.mipmap.elephant);
Animal tiger = new Animal("Tiger",R.mipmap.tiger);
Animal monkey = new Animal("Monkey",R.mipmap.monkey);
animals.add(lion);
animals.add(cat);
animals.add(dog);
animals.add(elephant);
animals.add(tiger);
animals.add(monkey);
}
}
运行结果：
[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-KoHVolT3-1639229809769)(C:\Users\E\AppData\Roaming\Typora\typora-user-images\image-20211210215458084.png)]
新compose方法
一个简单的示例：
物品类
package com.eric.composetest
object SampleData {
val Sample = listOf(
Message("liu de hua","a singer"),
Message("zhangxueyou", "also a singer"),
Message("kitty","very cute")
)
}
主kt代码
package com.eric.composetest
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.Image
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Surface
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import com.eric.composetest.ui.theme.ComposeTestTheme
class MainActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
ComposeTestTheme {
// A surface container using the 'background' color from the theme
Surface(color = MaterialTheme.colors.background) {
DispMessages(messages = SampleData.Sample)
}
}
}
}
@Composable
fun MessageCard(msg: Message) {
Row(
modifier = Modifier.padding(all= 10.dp)
) {
Image(painter = painterResource(id = R.mipmap.cat), contentDescription = "a cute kitty",
modifier = Modifier
.clip(CircleShape)
.size(40.dp))
Spacer(modifier = Modifier.padding(5.dp))
Column {
Text(text = msg.head)
Spacer(modifier = Modifier.height(1.dp))
Text(text = msg.body)
}
}
}
@Composable
fun DispMessages(messages: List<Message>){
LazyColumn {
items(messages) {
message ->
MessageCard(message)
}
}
}
}
data class Message(val head:String, val body:String)
运行结果：
[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-9hRRx81m-1639229809771)(C:\Users\E\AppData\Roaming\Typora\typora-user-images\image-20211210224930458.png)]
作者：一位路过的假面骑士
原文链接：
}
}
}
@Composable
fun DispMessages(messages: List<Message>){
LazyColumn {
items(messages) { message ->
MessageCard(message)
}
}
}
}
data class Message(val head:String, val body:String)
### 运行结果：
[外链图片转存中...(img-9hRRx81m-1639229809771)]
###### 作者：一位路过的假面骑士
###### 原文链接：
https://blog.csdn.net/zeknes/article/details/121866517?spm=1001.2014.3001.5501