我遇到了这个问题。实际上,我正在做的是,在SQLitedatabase中插入记录并获取这些记录以在列表视图中显示。
以下是代码:
package com.activities.sqlitedbtest;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import com.db.recordStore.Contact;
import com.db.recordStore.DBHelper;
public class ListManagerActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_manager); **//edit and Uncommented this line**
ListView listView = (ListView) findViewById(R.id.listView1); **//this line return null value..**
Log.d("ListView :: ", ""+listView); **// printing null value**
DBHelper helper = new DBHelper(this);
List<Contact> list = helper.getAllRecords();
String[] records = new String[list.size()];
Log.d("Records count ", ""+records.length);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.activity_list_manager, records);
listView.setAdapter(adapter);
}
}
此外,activity_list_manager.xml为:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.activities.sqlitedbtest.ListManagerActivity"
tools:ignore="MergeRootFrame" >
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" >
</ListView>
</RelativeLayout>
我正在尝试在listView中显示列表。单击按钮此活动(ListManagerActivity)被调用。
这就是我所做的另一项活动:
Intent i = new Intent(this,ListManagerActivity.class);
startActivity(i);
无法理解我做错了什么。在logCat中显示以下错误:
修改
08-14 20:02:20.985: D/OpenGLRenderer(2446): TextureCache::get: create texture(0xb89b1b38): name, size, mSize = 29, 7488, 1116068
08-14 20:02:21.205: D/dalvikvm(2446): GC_CONCURRENT freed 151K, 3% free 8205K/8391K, paused 12ms+1ms, total 18ms
08-14 20:02:21.209: D/ListView ::(2446): android.widget.ListView@53517528
08-14 20:02:21.225: D/Records count(2446): 2
08-14 20:02:21.245: E/ArrayAdapter(2446): You must supply a resource ID for a TextView
08-14 20:02:21.245: D/AndroidRuntime(2446): Shutting down VM
08-14 20:02:21.249: W/dalvikvm(2446): threadid=1: thread exiting with uncaught exception (group=0xa6260288)
08-14 20:02:21.253: E/AndroidRuntime(2446): FATAL EXCEPTION: main
08-14 20:02:21.253: E/AndroidRuntime(2446): java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:386)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.AbsListView.obtainView(AbsListView.java:2267)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.ListView.measureHeightOfChildren(ListView.java:1244)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.ListView.onMeasure(ListView.java:1156)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.View.measure(View.java:15172)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.RelativeLayout.measureChild(RelativeLayout.java:602)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:415)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.View.measure(View.java:15172)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.View.measure(View.java:15172)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.LinearLayout.measureVertical(LinearLayout.java:833)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.View.measure(View.java:15172)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
08-14 20:02:21.253: E/AndroidRuntime(2446): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.View.measure(View.java:15172)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.Choreographer.doCallbacks(Choreographer.java:555)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.Choreographer.doFrame(Choreographer.java:525)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.os.Handler.handleCallback(Handler.java:615)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.os.Handler.dispatchMessage(Handler.java:92)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.os.Looper.loop(Looper.java:137)
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.app.ActivityThread.main(ActivityThread.java:4745)
08-14 20:02:21.253: E/AndroidRuntime(2446): at java.lang.reflect.Method.invokeNative(Native Method)
08-14 20:02:21.253: E/AndroidRuntime(2446): at java.lang.reflect.Method.invoke(Method.java:511)
08-14 20:02:21.253: E/AndroidRuntime(2446): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-14 20:02:21.253: E/AndroidRuntime(2446): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-14 20:02:21.253: E/AndroidRuntime(2446): at dalvik.system.NativeStart.main(Native Method)
08-14 20:02:21.253: E/AndroidRuntime(2446): Caused by: java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to android.widget.TextView
08-14 20:02:21.253: E/AndroidRuntime(2446): at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:379)
08-14 20:02:21.253: E/AndroidRuntime(2446): ... 36 more
08-14 20:02:22.717: I/Process(2446): Sending signal. PID: 2446 SIG: 9
我用Google搜索了,但问题仍未解决。
我找到了this。
答案 0 :(得分:0)
您已对setContentView
的电话进行了评论。 Android还没有夸大该特定活动的任何布局,因此当您尝试查找视图时,它会返回null,因为它找不到任何内容。
取消注释下面的行,应该解决。
setContentView(R.layout.activity_list_manager);
答案 1 :(得分:0)
为“分配数组”值时使用以下行
这一行是android的内置ListRow模板android.R.layout.simple_list_item_1
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, records);
答案 2 :(得分:0)
此行ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.activity_list_manager, records);
是问题所在。您不应该将布局资源ID作为第二个参数传递。你传递一个代表每一行的布局或简单地使用这个android.R.layout.simple_list_item_1
。
试试这个:
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, records)
答案 3 :(得分:-1)
如果取消注释无效,我建议您使用ListActivity而不是Activity。
您可以在此处详细了解: http://developer.android.com/reference/android/app/ListActivity.html
XML中的ListView ID应为
机器人:ID =&#34; @android:ID /列表&#34;&#34;
在代码中你可以使用
ListView listView = getListView();