我对Android Developement来说是全新的,这是我第一天触及Android工作室。只是一个愚蠢的问题:我正在实施一个笔记记录应用程序,在我的主视图活动中,我必须这样做
public class MainActivity extends ListActivity {}
但原始代码是
public class MainActivity extends ActionBarActivity {}
MainActivity.java
package com.example.sunny.mynote;
import android.app.ListActivity;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import com.example.sunny.mynote.com.example.sunny.mynote.data.NoteDataSource;
import com.example.sunny.mynote.com.example.sunny.mynote.data.NoteItem;
import java.util.List;
public class MainActivity extends ActionBarActivity {
private NoteDataSource datasource;
List<NoteItem> notesList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
datasource = new NoteDataSource(this);
refreshDisplay();
}
private void refreshDisplay() {
notesList = datasource.findAll();
ArrayAdapter<NoteItem> adapter =
new ArrayAdapter<NoteItem>(this, R.layout.list_item_layout, notesList);
ListView lv = (ListView) findViewById(R.id.list);
lv.setListAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
activity_main.xml中
<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="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.example.mina.mynote.MainActivity">
<ListView
android:id="@android:id/list"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true" />
</RelativeLayout>
然而,这使得我的操作栏消失,我知道我不能将MainActivity继承到ActionBarActivity,因为Java不支持2继承,所以如何让我的操作栏出现?请帮助!!
答案 0 :(得分:1)
您需要做的是将一个listview放在ActionBarActivity中。将public class MainActivity extends ListActivity
更改回public class MainActivity extends ActionBarActivity
。然后你需要改变布局,以便列表视图有一个容器。你可以使用relativelayout:
<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="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.example.mina.mynote.MainActivity">
<ListView
android:id="@android:id/list"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true" />
</RelativeLayout>
然后,您需要更改此调用,您正在设置适配器:setListAdapter(adapter)
。您的活动不再继承ListActivity,因此它没有此方法。您需要首先获得对listview的引用,然后在其上调用setListAdapter()
:
ListView lv = (ListView) findViewById(R.id.list);
//setListAdapter becomes setAdapter
lv.setAdapter(adapter);
顺便说一句,考虑使用比“list”更不通用/模糊的内容来获取listview id。
我希望这会有所帮助。