在这里我只想在spinner android中的文本视图中设置文本，文本是从数据库获取的，但它总是出错java.lang.NullPointerExeception。 这是我的活动。 Erorr是以下登录代码。
public class Front_end_akreditasi extends Activity {
private DBDataSource dataSource;
MyAdapter spn;
// Spinner element
Spinner spinner;
ArrayList<Akreditasi> dataArr = new ArrayList<Akreditasi>();
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.front_end_akreditasi);
dataSource = new DBDataSource(this);
dataSource.open();
spinner = (Spinner) findViewById(R.id.spinner_show);
ArrayList<Akreditasi> values = dataSource.getnama_Akreditasi();
for (Akreditasi cn : values)
{
String log = "ID :" + cn.getId() + "Name: " + cn.getNama();
Log.d("Result: ", log);
dataArr.add(cn);
spn = new MyAdapter(this, R.layout.custom_spinner, dataArr);
spinner.setAdapter(spn);
}
}
public class MyAdapter extends ArrayAdapter<Akreditasi> {
Context context;
int layoutResourceId;
ArrayList<Akreditasi> data = new ArrayList<Akreditasi>();
public MyAdapter(Context ctx, int txtViewResourceId, ArrayList<Akreditasi> objects)
{
super(ctx, txtViewResourceId, objects);
this.layoutResourceId = txtViewResourceId;
this.context = ctx;
this.data = objects;
}
@Override
public View getDropDownView(int position, View cnvtView, ViewGroup prnt) {
return getCustomView(position, cnvtView, prnt);
}
@Override
public View getView(int pos, View cnvtView, ViewGroup prnt) {
return getCustomView(pos, cnvtView, prnt);
}
public View getCustomView(int position, View convertView, ViewGroup parent)
{
LayoutInflater inflater = getLayoutInflater();
View mySpinner = inflater.inflate(R.layout.custom_spinner, parent,false);
ImageHolder holder = null;
if(mySpinner == null)
{
holder = new ImageHolder();
holder.txtTitle = (TextView)mySpinner.findViewById(R.id.text_main_seen);
holder.imgIcon = (ImageView)mySpinner.findViewById(R.id.left_pic);
holder.txtName = (TextView)mySpinner.findViewById(R.id.sub_text_seen);
mySpinner.setTag(holder);
}
else
{
holder = (ImageHolder)mySpinner.getTag();
}
Akreditasi a = data.get(position);
//When i add this code below, then the program is error, it's says java.lang.NullPointerExeception
holder.txtTitle.setText("coba");
return mySpinner;
}
class ImageHolder
{
ImageView imgIcon;
TextView txtTitle;
TextView txtName;
}
这是我的custom_spinner.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="3px" >
<ImageView
android:id="@+id/left_pic"
android:layout_width="100px"
android:layout_height="80px"
android:background="@drawable/ic_launcher" />
<TextView
android:id="@+id/text_main_seen"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5px"
android:layout_marginTop="2px"
android:layout_toRightOf="@+id/left_pic"
android:padding="3px"
android:text="JMD Group"
android:textColor="#0022ee"
android:textSize="22px"
android:textStyle="bold" />
<TextView
android:id="@+id/sub_text_seen"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/text_main_seen"
android:layout_marginLeft="5dip"
android:layout_toRightOf="@+id/left_pic"
android:padding="2px"
android:text="beyond the expectations..."
android:textColor="#777777" />
</RelativeLayout>
这是我的日志
05-08 13:06:31.889: E/AndroidRuntime(16634): FATAL EXCEPTION: main
05-08 13:06:31.889: E/AndroidRuntime(16634): java.lang.NullPointerException
05-08 13:06:31.889: E/AndroidRuntime(16634): at com.example.frontend.category.search.Front_end_akreditasi$MyAdapter.getCustomView(Front_end _akreditasi.java:165)
05-08 13:06:31.889: E/AndroidRuntime(16634): at com.example.frontend.category.search.Front_end_akreditasi$MyAdapter.getView(Front_end_akred itasi.java:138)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:193)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.Spinner.onMeasure(Spinner.java:439)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.View.measure(View.java:15592)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.View.measure(View.java:15592)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.View.measure(View.java:15592)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.View.measure(View.java:15592)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
05-08 13:06:31.889: E/AndroidRuntime(16634): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2180)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.View.measure(View.java:15592)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1878)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4356)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.Choreographer.doFrame(Choreographer.java:532)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.os.Handler.handleCallback(Handler.java:725)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.os.Handler.dispatchMessage(Handler.java:92)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.os.Looper.loop(Looper.java:137)
05-08 13:06:31.889: E/AndroidRuntime(16634): at android.app.ActivityThread.main(ActivityThread.java:5099)
05-08 13:06:31.889: E/AndroidRuntime(16634): at java.lang.reflect.Method.invokeNative(Native Method)
05-08 13:06:31.889: E/AndroidRuntime(16634): at java.lang.reflect.Method.invoke(Method.java:511)
05-08 13:06:31.889: E/AndroidRuntime(16634): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:803)
05-08 13:06:31.889: E/AndroidRuntime(16634): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:570)
05-08 13:06:31.889: E/AndroidRuntime(16634): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：3)
尝试以下代码。我认为这应该有帮助
holder = new ImageHolder();
holder.txtTitle = (TextView)mySpinner.findViewById(R.id.text_main_seen);
holder.imgIcon = (ImageView)mySpinner.findViewById(R.id.left_pic);
holder.txtName = (TextView)mySpinner.findViewById(R.id.sub_text_seen);
if(mySpinner == null)
{
mySpinner.setTag(holder);
}
else
{
holder = (ImageHolder)mySpinner.getTag();
}
Akreditasi a = data.get(position);
holder.txtTitle.setText("coba");
return mySpinner;
}
问题可能是holder.txtTitle在其他情况下仍为null，因为您没有按ID查找其视图。
答案 1 :(得分：0)
我认为它没有获取上下文所以请使用下面的代码创建LayoutInflater
LayoutInflater mInflater = LayoutInflater.from(context);
而不是这个，
LayoutInflater inflater = getLayoutInflater();