使用ListView自定義佈局

摘要： 使用ListView自定義佈局 1.新建一個ListViewTest專案 2.修改MainActivity: package com.example.listviewtest; import android.support.v7.app.AppCompatActivity; im...

使用ListView自定義佈局

1.新建一個ListViewTest專案

2.修改MainActivity:

package com.example.listviewtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.AndroidCharacter;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MainActivity extends AppCompatActivity {

private String[] data = {
"apple", "bannana", "pear", "orange",
"apple", "bannana", "pear", "orange",
"apple", "bannana", "pear", "orange",
"apple", "bannana", "pear", "orange",
};


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

ArrayAdapter<String> adapter = new ArrayAdapter<String>(
MainActivity.this, android.R.layout.simple_list_item_1,data
);

ListView listView = (ListView) findViewById(R.id.list_view);
listView.setAdapter(adapter);


}
}

3.修改activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">

<ListView
android:id="@+id/list_view"
android:layout_width="match_parent"
android:layout_height="match_parent">

</ListView>
</LinearLayout>

效果展示如下:

4.使用ListView

新建一個類Fruit:

package com.example.listviewtest;

public class Fruit {

private String name;
private int imageId;

public Fruit(String name, int imageId) {
this.name = name;
this.imageId = imageId;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getImageId() {
return imageId;
}

public void setImageId(int imageId) {
this.imageId = imageId;
}
}

新建一個FruitAdapter:

package com.example.listviewtest;

import android.content.Context;
import android.support.annotation.IdRes;
import android.support.annotation.LayoutRes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.text.Layout;
import android.util.Log;
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 java.util.List;


public class FruitAdapter extends ArrayAdapter<Fruit> {
private static final String TAG = "FruitAdapter";


privateint resourceId;
public FruitAdapter( Context context,
int textViewResourceId,
List<Fruit> objects) {
super(context,textViewResourceId, objects);
resourceId = textViewResourceId;

}


@NonNull
@Override
public View getView(int position,
@Nullable View convertView,
@NonNull ViewGroup parent) {
Log.d(TAG, "position: "+position);
Fruit fruit = getItem(position); //獲取當前Fruit例項
View view = LayoutInflater.from(getContext()).inflate(
resourceId,parent,false
);

ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
TextView fruitName = (TextView) view.findViewById(R.id.fruit_name);

fruitImage.setImageResource(fruit.getImageId());
fruitName.setText(fruit.getName());
return view;
}
}

fruit_item.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">

<ImageView
android:id="@+id/fruit_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

<TextView
android:id="@+id/fruit_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginLeft="10dp"
/>
</LinearLayout>

MainActivity:

package com.example.listviewtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.AndroidCharacter;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

private List<Fruit> fruitList = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruits();//初始化水果資料
FruitAdapter adapter = new FruitAdapter(

MainActivity.this,R.layout.fruit_item,
fruitList

);
ListView listView = (ListView) findViewById(R.id.list_view);
listView.setAdapter(adapter);


}

private void initFruits() {


for (int i = 0; i <10 ; i++) {

Fruit apple = new Fruit("apple",R.drawable.apple);
fruitList.add(apple);
Fruit orange = new Fruit("orange",R.drawable.orange);
fruitList.add(orange);



}


}
}

提升ListView的執行效率

ListView這個控制元件實際上是很難用的,就是因為它很多細節可以優化,效率就是比較重要的一點.下面我們來優化下它的效率:

FruitAdapter:

package com.example.listviewtest;

import android.content.Context;
import android.support.annotation.IdRes;
import android.support.annotation.LayoutRes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.text.Layout;
import android.util.Log;
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 java.util.List;


public class FruitAdapter extends ArrayAdapter<Fruit> {
private static final String TAG = "FruitAdapter";


private int resourceId;

public FruitAdapter(Context context,
int textViewResourceId,
List<Fruit> objects) {
super(context, textViewResourceId, objects);
resourceId = textViewResourceId;

}


@NonNull
@Override
public View getView(int position,
@Nullable View convertView,
@NonNull ViewGroup parent) {
Log.d(TAG, "position: " + position);
Fruit fruit = getItem(position); //獲取當前Fruit例項
View view;
ViewHolder viewHolder;
if (convertView == null) {
view = LayoutInflater.from(getContext()).inflate(
resourceId, parent, false
);

viewHolder = new ViewHolder();

viewHolder.fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
viewHolder.fruitName = (TextView) view.findViewById(R.id.fruit_name);

view.setTag(viewHolder);//將viewHolder儲存在view中

} else {
view = convertView;
viewHolder = (ViewHolder) view.getTag();//重新獲取viewHolder
}

viewHolder.fruitImage.setImageResource(fruit.getImageId());
viewHolder.fruitName.setText(fruit.getName());
return view;
}

class ViewHolder {
ImageView fruitImage;
TextView fruitName;
}


}

這裡對convertView進行重用,用viewHolder來取資料,提高了效率.

ListView的點選事件

修改MainActivity:

package com.example.listviewtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.AndroidCharacter;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

private List<Fruit> fruitList = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruits();//初始化水果資料
FruitAdapter adapter = new FruitAdapter(

MainActivity.this,R.layout.fruit_item,
fruitList

);
ListView listView = (ListView) findViewById(R.id.list_view);
listView.setAdapter(adapter);

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent,
View view,
int position,
long id) {
Fruit fruit = fruitList.get(position);
Toast.makeText(MainActivity.this,

fruit.getName(),
Toast.LENGTH_SHORT
).show();
}
});

}

private void initFruits() {

for (int i = 0; i <10 ; i++) {

Fruit apple = new Fruit("apple",R.drawable.apple);
fruitList.add(apple);
Fruit orange = new Fruit("orange",R.drawable.orange);
fruitList.add(orange);

}

}
}