Why should I use an additional layout file to present a ListView? [closed]

问题

I am new in android technology and learning via net tutorials. While binding List View i am in a confusion that why we create a separate layout file and call that layout file in arrayadapter

回答1:

Source for the code shown below: http://www.vogella.com/articles/AndroidListView/article.html

When you are creating a simple ListView, you will use something like this:

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" >

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

</LinearLayout>

JAVA:

ListView listView = (ListView) findViewById(R.id.mylist);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
        "Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
        "Linux", "OS/2" };

// Define a new Adapter
// First parameter - Context
// Second parameter - Layout for the row
// Third parameter - ID of the TextView to which the data is written
// Forth - the Array of data

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
        android.R.layout.simple_list_item_1, android.R.id.text1, values);


// Assign adapter to ListView
listView.setAdapter(adapter);

When creating a custom ListView, you will typically do something like this:

package de.vogella.android.listactivity;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MySimpleArrayAdapter extends ArrayAdapter<String> {
    private final Context context;
    private final String[] values;

    public MySimpleArrayAdapter(Context context, String[] values) {
        super(context, R.layout.rowlayout, values);
        this.context = context;
        this.values = values;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View rowView = inflater.inflate(R.layout.rowlayout, parent, false);
        TextView textView = (TextView) rowView.findViewById(R.id.label);
        ImageView imageView = (ImageView) rowView.findViewById(R.id.icon);
        textView.setText(values[position]);
        // Change the icon for Windows and iPhone
        String s = values[position];
        if (s.startsWith("iPhone")) {
            imageView.setImageResource(R.drawable.no);
        } else {
            imageView.setImageResource(R.drawable.ok);
        }
        return rowView;
    }
}

In this example, if you look at the line: View rowView = inflater.inflate(R.layout.rowlayout, parent, false);, the R.layout.rowlayout is your custom layout used to show your custom ListView.

Refer to the source link at the top of the answer for a detailed tutorial on ListView's.

回答2:

You don't have to create a separate layout. You can create layouts on run time.

回答3:

separate xml is created for every row of listview. listview needs items to display, so that should be displayed using some view like textview,imageview......So depending upon the need you need that layout.

来源：https://stackoverflow.com/questions/15378150/why-should-i-use-an-additional-layout-file-to-present-a-listview

标签

android

android-listview