listview简单使用与优化

来源：互联网发布：逛淘宝免流量编辑：程序博客网时间：2024/05/21 12:50

对于很多初学者来说，listview一直是一个难点，刚才整理了一段代码，介绍了listview的使用方式与简单优化，以及item的更新

<1.XML主布局>

<?xml version="1.0" encoding="utf-8"?><LinearLayout 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"    android:orientation="vertical">    <Button        android:layout_width="match_parent"        android:layout_height="60dp"        android:text="点我刷新"        android:textSize="20.0sp"        android:gravity="center"        android:id="@+id/update" />    <ListView        android:layout_width="match_parent"        android:layout_height="match_parent"        android:id="@+id/listview"/></LinearLayout>

<2.item布局>

<?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">    <LinearLayout        android:layout_width="match_parent"        android:layout_height="60dp"        android:orientation="vertical">        <TextView            android:layout_width="match_parent"            android:layout_height="match_parent"            android:text="你好世界"            android:textSize="20.0sp"            android:gravity="center"            android:id="@+id/tv_show"/>    </LinearLayout></LinearLayout>

<3.适配器>

public class MyAdapter extends BaseAdapter {    private Context context;    private List<String> list;    public MyAdapter(List<String> list, Context context) {        this.list = list;        this.context = context;    }    @Override    public int getCount() {        if(list!=null)            return list.size();        return 0;    }    @Override    public Object getItem(int position) {        return position;    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        MyHolder myHolder;        if(convertView==null){            myHolder=new MyHolder();            convertView= LayoutInflater.from(context).inflate(R.layout.list_item,null);            myHolder.textView= (TextView) convertView.findViewById(R.id.tv_show);            convertView.setTag(myHolder);        }else {            myHolder= (MyHolder) convertView.getTag();        }        myHolder.textView.setText(list.get(position).toString());        return convertView;    }    //listview的一种优化方式    private class MyHolder{        TextView textView;    }}

<4.源代码>

public class MainActivity extends AppCompatActivity {    private ListView listView;    private Button button;    private MyAdapter myAdapter;    private List<String> list;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        init();        list=new ArrayList<>();        for(int i=0;i<10;i++){            list.add("我是显示文本"+i);        }        myAdapter=new MyAdapter(list,this);        listView.setAdapter(myAdapter);        //对刷新按钮添加监听事件        button.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                list.clear();                for(int i=0;i<10;i++){                    list.add("我是更新文本"+i);                }

//通知适配器改变文本信息                myAdapter.notifyDataSetChanged();            }        });    }    //实例化控件    private void init(){        listView= (ListView) findViewById(R.id.listview);        button= (Button) findViewById(R.id.update);    }}

希望对你有所帮助

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