《RadioButton與ListView的混合使用》一文中,我在擴充卡中用标記的方法實作了使用者選擇的操作,這次用ListView的單選模式來實作一下。ListView的預設狀态下是沒有選擇行為的,把ListView的choiceMode設定為singleChoice,清單就可以實作單選(當然它也有多選模式,這個後面再研究)。
Activity的布局檔案如下,ListView選擇了單選模式,這次我把ListView上方的TextView換成了Button:
<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:id="@+id/select"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="@string/select_authors"
android:textSize="25sp" />
<ListView
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:choiceMode="singleChoice" />
</LinearLayout>
ItemList的XML檔案,RadioButton換成了CheckBox,另外, CheckBox 是可以擷取焦點的UI控件,為實作ListView的點選,需要設定
“ android:clickable="false"
android:focusable="false"
android:focusableInTouchMode="false"”
這三項,其中,CheckBox的背景選用了自己做的一張圖檔,圖檔是RadioButton的樣子:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:background="#fff" >
<TextView
android:id="@+id/author"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:padding="10dp"
android:textSize="20sp" />
<CheckBox
android:id="@+id/radio"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_gravity="center_vertical"
android:layout_marginRight="10dp"
android:background="@drawable/radio_button_normal"
android:button="@null"
android:clickable="false"
android:focusable="false"
android:focusableInTouchMode="false"
android:padding="10dp" />
</RelativeLayout>
Activity的代碼如下,點選ListView的Item或者其上方的Button,都可以彈出Toast:
package com.example.choicelistviewtest;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
public class RadioButtonListActivity extends Activity {
private ListView radioButtonList;
private RadioAdapter adapter;
// 模拟幾個資料,作為List的條目
private String[] authors = { "芥川龍之介", "三島由紀夫", "川端康成", "村上春樹", "東野圭吾",
"張愛玲", "金庸", "錢鐘書", "老舍", "梁實秋", "亨利米勒", "海明威", "菲茲傑拉德", "凱魯亞克",
"傑克倫敦", "小仲馬", "杜拉斯", "福樓拜", "雨果", "巴爾紮克", "莎士比亞", "勞倫斯", "毛姆",
"柯南道爾", "笛福" };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_choice_list_view_test);
radioButtonList = (ListView) findViewById(R.id.list);
adapter = new RadioAdapter(this, authors);
radioButtonList.setAdapter(adapter);
radioButtonList.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
Toast.makeText(RadioButtonListActivity.this,
"您選擇的作家是:" + authors[arg2], Toast.LENGTH_SHORT).show();
}
});
findViewById(R.id.select).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
int select = radioButtonList.getCheckedItemPosition();
// INVALID_POSITION 代表無效的位置。有效值的範圍是 0 到目前擴充卡項目數減 1 。
if (ListView.INVALID_POSITION != select) {
Toast.makeText(RadioButtonListActivity.this,
"您選擇的作家是:" + authors[select], Toast.LENGTH_SHORT)
.show();
} else {
// 如果使用者開始沒有選擇
Toast.makeText(RadioButtonListActivity.this, "請選擇一位作家!",
Toast.LENGTH_SHORT).show();
}
}
});
}
}
擴充卡:
package com.example.choicelistviewtest;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
public class RadioAdapter extends BaseAdapter {
private String[] authors;
private Context c;
public RadioAdapter(Context c, String[] authors) {
super();
this.c = c;
this.authors = authors;
}
@Override
public int getCount() {
return authors.length;
}
@Override
public Object getItem(int arg0) {
return null;
}
@Override
public long getItemId(int arg0) {
return 0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
ChoiceListItemView choiceListItemView = new ChoiceListItemView(c, null);
choiceListItemView.setName(authors[arg0]);
return choiceListItemView;
}
}
ListView是通過實作Checkable接口來處理單選模式的,這要求Item的視圖實作Checkable接口,建立ChoiceListItemView類來實作該接口,ListView選中某個Item時,會調用ChoiceListItemView類的setChecked的方法:
package com.example.choicelistviewtest;
import android.content.Context;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.CheckBox;
import android.widget.Checkable;
import android.widget.LinearLayout;
import android.widget.TextView;
public class ChoiceListItemView extends LinearLayout implements Checkable {
private TextView nameTxt;
private CheckBox selectBtn;
public ChoiceListItemView(Context context, AttributeSet attrs) {
super(context, attrs);
LayoutInflater inflater = LayoutInflater.from(context);
View v = inflater.inflate(R.layout.item_list, this, true);
nameTxt = (TextView) v.findViewById(R.id.author);
selectBtn = (CheckBox) v.findViewById(R.id.radio);
}
public void setName(String text) {
nameTxt.setText(text);
}
@Override
public boolean isChecked() {
return selectBtn.isChecked();
}
@Override
public void setChecked(boolean checked) {
selectBtn.setChecked(checked);
//根據是否選中來選擇不同的背景圖檔
if (checked) {
selectBtn.setBackgroundResource(R.drawable.radio_button_checked);
} else {
selectBtn.setBackgroundResource(R.drawable.radio_button_normal);
}
}
@Override
public void toggle() {
selectBtn.toggle();
}
}
效果圖: