最近寫了一個關於Android開發的項目,其中用到了ListView,在這裏總結一下。這是我的ListView
<?xml version="1.0" encoding="utf-8"?>
<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">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<ListView
android:id="@+id/topicliist"
android:layout_width="match_parent"
android:layout_height="wrap_content"
tools:layout_editor_absoluteX="8dp"
tools:layout_editor_absoluteY="8dp" />
</LinearLayout>
</android.support.constraint.ConstraintLayout>
之後再創建一個自己想用ListView顯示的Item,因爲我的是顯示選擇題,所以會有點多
<?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">
<TextView
android:id="@+id/questionS"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="選擇題"
android:textSize="28sp"/>
<RadioGroup
android:id="@+id/selectanwser"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<RadioButton
android:id="@+id/optionA"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="28sp"/>
<RadioButton
android:id="@+id/optionB"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="28sp"/>
<RadioButton
android:id="@+id/optionC"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="28sp"/>
<RadioButton
android:id="@+id/optionD"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="28sp"/>
</RadioGroup>
</LinearLayout>
在Activity中
import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class TopicActivity extends AppCompatActivity {
private ListView topicList;
private List<Topic> topics=new ArrayList<Topic>();
private TopicAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_topic);
topicList=(ListView)findViewById(R.id.topicliist);
init();
adapter=new TopicAdapter(TopicActivity.this
,R.layout.topic_select_item,topicSelect);
//將數據放入Adapter
topicList.setAdapter(adapter);
addquestion.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
LayoutInflater inflater = (LayoutInflater) TopicActivity.this.getSystemService(LAYOUT_INFLATER_SERVICE);
public void init()
{
Topic t2=new Topic();
t2.setQuestion("問題()");
t2.setA("A");
t2.setB("B");
t2.setC("C");
t2.setD("D");
topicSelect.add(t2);
}
}
其中TopicAdapter如下:
package login.example.coursemanager;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.RadioButton;
import android.widget.TextView;
import java.util.List;
public class TopicAdapter extends ArrayAdapter<Topic> {
private int resourceId;
private List<Topic> mlist;
public TopicAdapter(Context context,int textViewResourceId,List<Topic> objects)
{
super(context,textViewResourceId,objects);
resourceId=textViewResourceId;
mlist=objects;
}
public View getView(int position, View convertView, ViewGroup parent)
{
Topic topic=getItem(position);
View view ;
TopicAdapter.ViewHolder viewHolder;
if(convertView == null) {
view= LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
viewHolder=new TopicAdapter.ViewHolder();
viewHolder.question=(TextView)view.findViewById(R.id.questionS);
viewHolder.optionA=(RadioButton)view.findViewById(R.id.optionA);
viewHolder.optionB=(RadioButton)view.findViewById(R.id.optionB);
viewHolder.optionC=(RadioButton)view.findViewById(R.id.optionC);
viewHolder.optionD=(RadioButton)view.findViewById(R.id.optionD);
view.setTag(viewHolder);
}
else
{
view=convertView;
viewHolder=(TopicAdapter.ViewHolder) view.getTag();
}
viewHolder.question.setText(topic.getQuestion());
viewHolder.optionA.setText(topic.getA());
viewHolder.optionB.setText(topic.getB());
viewHolder.optionC.setText(topic.getC());
viewHolder.optionD.setText(topic.getD());
return view;
}
class ViewHolder
{
TextView question;
RadioButton optionA;
RadioButton optionB;
RadioButton optionC;
RadioButton optionD;
TextView anwser;
}
public void refresh(List<Topic> l)
{
mlist=l;
notifyDataSetChanged();
}
}
Topic只是一個普通的類,包含四個選項和問題的屬性,均是String類型的。像這樣寫Adapter可以提高LIstView的效率,每次刷新不用全部重新加載。
對於ListView的即時更新問題,可以自己寫一個refresh方法,也可以調用他自帶的notifyDataSetChanged()方法,每次只要在List對象發生改變的時候最直接調用,就可以刷新ListView。