Android控件之ListView用法实例详解

2020-04-11 11:26:29

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本文实例讲述了Android控件之ListView用法。分享给大家供大家参考。具体如下：

示例一：

在android开发中ListView是比较常用的组件，它以列表的形式展示具体内容，并且能够根据数据的长度自适应显示。

main.xml布局文件：

<?xml version="1.0" encoding="utf-8"?><LinearLayout android:id="@+id/LinearLayout01"  android:layout_width="fill_parent" android:layout_height="fill_parent"  xmlns:android="http://schemas.android.com/apk/res/android">  <ListView android:layout_width="wrap_content"    android:layout_height="wrap_content"     android:id="@+id/MyListView">  </ListView></LinearLayout>

my_listitem.xml布局文件：

<?xml version="1.0" encoding="utf-8"?><LinearLayout android:layout_width="fill_parent"  xmlns:android="http://schemas.android.com/apk/res/android"  android:orientation="vertical"   android:layout_height="wrap_content"  android:id="@+id/myListItem"   android:paddingBottom="3dip"  android:paddingLeft="10dip">  <TextView android:layout_height="wrap_content"    android:layout_width="fill_parent"     android:id="@+id/itemTitle"    android:textSize="20dip">  </TextView>  <TextView android:layout_height="wrap_content"    android:layout_width="fill_parent"     android:id="@+id/itemText">  </TextView></LinearLayout>

LsActivity类：

package com.ljq.ls;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.widget.ListView;import android.widget.SimpleAdapter;public class LsActivity extends Activity {  private ListView list = null;  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    list = (ListView) findViewById(R.id.MyListView);    //组织数据源    List<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();    for(int i=0;i<10;i++) {      HashMap<String, String> map = new HashMap<String, String>();      map.put("itemTitle", "This is Title");      map.put("itemText", "This is text");      mylist.add(map);    }    //配置适配器    SimpleAdapter adapter = new SimpleAdapter(this,      mylist,//数据源      R.layout.my_listitem,//显示布局     new String[] {"itemTitle", "itemText"}, //数据源的属性字段     new int[] {R.id.itemTitle,R.id.itemText}); //布局里的控件id    //添加并且显示    list.setAdapter(adapter);  }}

运行结果如下图所示：

示例二：

目录结构

main.xml布局文件：

<?xml version="1.0" encoding="utf-8"?><!-- 使用相对布局 --><RelativeLayout  xmlns:android="http://schemas.android.com/apk/res/android"  android:orientation="vertical"   android:layout_width="wrap_content"  android:layout_height="wrap_content">  <TextView android:layout_width="100dip"    android:layout_height="wrap_content"    android:layout_marginLeft="30dip"    android:textSize="20dip"    android:id="@+id/id"/>  <TextView android:layout_width="100dip"    android:layout_height="wrap_content"    android:layout_alignTop="@id/id"    android:layout_toRightOf="@id/id"    android:textSize="20dip"    android:id="@+id/name"/>  <TextView android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_alignTop="@id/name"    android:layout_toRightOf="@id/name"    android:textSize="20dip"    android:id="@+id/age"/></RelativeLayout>

实体JavaBean：

package com.ljq.domain;public class Person {  private String id;  private String name;  private String age;  public Person() {    super();  }  public Person(String id, String name, String age) {    super();    this.id = id;    this.name = name;    this.age = age;  }  public String getId() {    return id;  }  public void setId(String id) {    this.id = id;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public String getAge() {    return age;  }  public void setAge(String age) {    this.age = age;  }}

自定义适配器PersonAdapter

package com.ljq.ls;import java.util.List;import com.ljq.domain.Person;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.TextView;/** * ListView加载adapter的过程 *  * 1、先判断adapter有多少数据项，根据这个数据确定有多少个item *  * 2、确定每个item里加载哪个view *  * 3、在view里加载要显示的数据 *  * @author jiqinlin * */public class PersonAdapter extends ArrayAdapter{  private LayoutInflater layoutInflater = null;  private List<Person> persons;  public PersonAdapter(Context context, int textViewResourceId, List objects) {    super(context, textViewResourceId, objects);    layoutInflater = LayoutInflater.from(context);    persons = objects;  }  /**   * 获取adapter里有多少个数据项   */  @Override  public int getCount() {    return persons.size();  }  @Override  public Object getItem(int position) {    return persons.get(position);  }  @Override  public long getItemId(int position) {    return position;  }   /**   * 创建显示的数据界面   *    * Adapter的作用就是ListView界面与数据之间的桥梁，   * 当列表里的每一项显示到页面时，都会调用Adapter的getView方法返回一个View。   * 想过没有？ 在我们的列表有1000000项时会是什么样的？是不是会占用极大的系统资源？   */  @Override  public View getView(int position, View convertView, ViewGroup parent) {    /*    // 优化前    ViewHolder holder = new ViewHolder();    convertView = layoutInflater.inflate(R.layout.main, null);    holder.id = (TextView)convertView.findViewById(R.id.id);    holder.name = (TextView)convertView.findViewById(R.id.name);    holder.age = (TextView)convertView.findViewById(R.id.age);    convertView.setTag(holder);    holder.id.setText(persons.get(position).getId());    holder.name.setText(persons.get(position).getName());    holder.age.setText(persons.get(position).getAge());    return convertView;    */    // 优化后    ViewHolder holder;    if(convertView == null){      convertView = layoutInflater.inflate(R.layout.main, null);      holder = new ViewHolder();      holder.id = (TextView)convertView.findViewById(R.id.id);      holder.name = (TextView)convertView.findViewById(R.id.name);      holder.age = (TextView)convertView.findViewById(R.id.age);      convertView.setTag(holder);    }else{      holder = (ViewHolder)convertView.getTag();    }    holder.id.setText(persons.get(position).getId());    holder.name.setText(persons.get(position).getName());    holder.age.setText(persons.get(position).getAge());    return convertView;  }  /**   * 界面上的显示控件   *    * @author jiqinlin   *   */  private static class ViewHolder{    private TextView id;    private TextView name;    private TextView age;  }}

类LsActivity

package com.ljq.ls;import java.util.ArrayList;import android.app.ListActivity;import android.os.Bundle;import android.view.View;import android.widget.ListView;import android.widget.Toast;import com.ljq.domain.Person;public class LsActivity extends ListActivity {  private ArrayList<Person> persons = new ArrayList<Person>();  private PersonAdapter personAdapter = null;  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);        initData();    personAdapter =new PersonAdapter(LsActivity.this, R.layout.main, persons);    setListAdapter(personAdapter);    registerForContextMenu(getListView());  }  @Override  protected void onListItemClick(ListView l, View v, int position, long id) {    super.onListItemClick(l, v, position, id);    Person person = persons.get(position);    Toast.makeText(LsActivity.this, person.getId()+":"+person.getName()        +":"+person.getAge(), Toast.LENGTH_LONG).show();    return;  }  private void initData(){    persons.add(new Person("序号", "姓名", "年龄"));    persons.add(new Person("1", "ljq1", "20"));    persons.add(new Person("2", "ljq2", "20"));    persons.add(new Person("3", "ljq3", "20"));    persons.add(new Person("4", "ljq4", "20"));    persons.add(new Person("5", "ljq5", "20"));    persons.add(new Person("6", "ljq6", "20"));    persons.add(new Person("7", "ljq7", "20"));    persons.add(new Person("8", "ljq8", "20"));    persons.add(new Person("9", "ljq9", "20"));  }}

运行结果