每个listview列包含5textview -ID，Initial，Date，Location，Ward。
我试图通过初始化来过滤listview。但是，我在第166行遇到了一个空例外。
我假设editText没有按初始过滤，似乎每次调用适配器都会导致错误消息。因此，我认为问题在于适配器。
package com.example.medilearner;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import com.medilearner.database.patientDbAdapter;
public class PatientDetails extends Activity {
// Database adapter
patientDbAdapter patientDB;
Context myContext;
// ArrayAdapter
ArrayAdapter<String> adapter;
ArrayList<HashMap<String, String>> encouterlist = new ArrayList<HashMap<String, String>>();
// Various layout
ListView patientList;
static String value;
private EditText filterText = null;
private static final String TAG_E_ID = "e_id";
private static final String TAG_E_INITIAL = "entry_initial";
private static final String TAG_E_DATE = "entry_date";
private static final String TAG_E_SITELOCATION = "entry_sitelocation";
private static final String TAG_E_WARDCLINIC = "entry_clinic";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_patient_details);
encouterlist = new ArrayList<HashMap<String, String>>();
myContext = this;
patientDB = new patientDbAdapter(myContext);
patientDB.open();
Cursor mCursor = patientDB.retrieveAllPatientEntriesCursor();
int count = mCursor.getCount();
if ((mCursor != null) && (mCursor.getCount() > 0)) {
mCursor.moveToFirst();
do {
// Get the data
// Convert the initial to String
String ID = mCursor.getString(0);
String Initial = mCursor.getString(1);
String Date = mCursor.getString(2);
String SiteLocation = mCursor.getString(3);
String WardClinic = mCursor.getString(4);
// Indicate that it's successful
Log.i("Successful retrival of", Initial);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_E_ID, ID);
map.put(TAG_E_INITIAL, Initial);
map.put(TAG_E_DATE, "Last Diagnosis: " + Date);
map.put(TAG_E_SITELOCATION, "Location: " + SiteLocation);
map.put(TAG_E_WARDCLINIC, "Ward: " + WardClinic);
// Add it to the array such that i can handle the array
// afterwhich
encouterlist.add(map);
}
// move to the next row
while (mCursor.moveToNext());
}
filterText = (EditText) findViewById(R.id.patientDetailsSearch);
filterText.addTextChangedListener(filterTextWatcher);
// need to link the layout
patientList = (ListView) findViewById(R.id.PatientDetailslist);
patientList.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view,
int position, long id) {
String str = encouterlist.get(+position).get("e_id");
String name = encouterlist.get(+position).get("entry_initial");
patientDB.open();
patientDB.removeEntry(str);
patientDB.close();
// PatientDetails.this.recreate();
Toast.makeText(myContext, name + " Deleted", Toast.LENGTH_SHORT).show();
// TODO Auto-generated method stub
return true;
}
}
);
patientList
.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(
PatientDetails.this,
encouterlist.get(+position)
.get("entry_initial") + " Selected",
Toast.LENGTH_SHORT).show();
Intent localIntent = new Intent(PatientDetails.this,
PatientInfo.class);
String str = encouterlist.get(+position).get("e_id");
localIntent.putExtra("value", str);
PatientDetails.this.setResult(-1, localIntent);
PatientDetails.this.finish();
}
}
);
ListAdapter adapter = new SimpleAdapter(PatientDetails.this,
encouterlist, R.layout.list_patient, new String[] { TAG_E_ID,
TAG_E_INITIAL, TAG_E_DATE, TAG_E_SITELOCATION,
TAG_E_WARDCLINIC }, new int[] { R.id.eid,
R.id.epatientInitial, R.id.epatientDate,
R.id.epatientSiteLocation, R.id.epatientWardClinci });
this.patientList.setAdapter(adapter);
};
private TextWatcher filterTextWatcher = new TextWatcher() {
public void afterTextChanged(Editable s) {
}
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
}
public void onTextChanged(CharSequence s, int start, int before,
int count) {
adapter.getFilter().filter(s);
}
};
protected void onDestroy() {
super.onDestroy();
filterText.removeTextChangedListener(filterTextWatcher);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.patient_details, menu);
return true;
}
}
logcat的
12-09 17:01:07.600: E/AndroidRuntime(25728): FATAL EXCEPTION: main
12-09 17:01:07.600: E/AndroidRuntime(25728): java.lang.NullPointerException
12-09 17:01:07.600: E/AndroidRuntime(25728): at com.example.medilearner.PatientDetails$1.onTextChanged(PatientDetails.java:166)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.widget.TextView.sendOnTextChanged(TextView.java:7426)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.widget.TextView.handleTextChanged(TextView.java:7488)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:9260)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:962)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:496)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:435)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:30)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.view.inputmethod.BaseInputConnection.replaceText(BaseInputConnection.java:676)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.view.inputmethod.BaseInputConnection.setComposingText(BaseInputConnection.java:435)
12-09 17:01:07.600: E/AndroidRuntime(25728): at com.android.internal.view.IInputConnectionWrapper.executeMessage(IInputConnectionWrapper.java:333)
12-09 17:01:07.600: E/AndroidRuntime(25728): at com.android.internal.view.IInputConnectionWrapper$MyHandler.handleMessage(IInputConnectionWrapper.java:77)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.os.Handler.dispatchMessage(Handler.java:99)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.os.Looper.loop(Looper.java:137)
12-09 17:01:07.600: E/AndroidRuntime(25728): at android.app.ActivityThread.main(ActivityThread.java:4921)
12-09 17:01:07.600: E/AndroidRuntime(25728): at java.lang.reflect.Method.invokeNative(Native Method)
12-09 17:01:07.600: E/AndroidRuntime(25728): at java.lang.reflect.Method.invoke(Method.java:511)
12-09 17:01:07.600: E/AndroidRuntime(25728): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
12-09 17:01:07.600: E/AndroidRuntime(25728): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
12-09 17:01:07.600: E/AndroidRuntime(25728): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
这是因为
public void onTextChanged(CharSequence s, int start, int before,
int count) {
adapter.getFilter().filter(s);
}
您的adapter为空。您正在本地创建ListAdapter adapter，这在范围之外没有意义。您可以使用全局的，而不是在本地创建ListAdapter。
答案 1 :(得分：0)
您创建列表适配器的本地实例
ListAdapter adapter = new SimpleAdapter(PatientDetails.this ....
在您的文本观察器中，您正在使用memeber adapter
尝试更改为
this.adapter = new SimpleAdapter(PatientDetails.this ....
答案 2 :(得分：0)
嗨，请完成代码示例
import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
public class MainActivity extends Activity {
// List view
private ListView lv;
// Listview Adapter
ArrayAdapter<String> adapter;
// Search EditText
EditText inputSearch;
// ArrayList for Listview
ArrayList<HashMap<String, String>> productList;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Listview Data
String products[] = {"Dell Inspiron", "HTC One X", "HTC Wildfire S", "HTC Sense", "HTC Sensation XE",
"iPhone 4S", "Samsung Galaxy Note 800",
"Samsung Galaxy S3", "MacBook Air", "Mac Mini", "MacBook Pro"};
lv = (ListView) findViewById(R.id.list_view);
inputSearch = (EditText) findViewById(R.id.inputSearch);
// Adding items to listview
adapter = new ArrayAdapter<String>(this, R.layout.list_item, R.id.product_name, products);
lv.setAdapter(adapter);
/**
* Enabling Search Filter
* */
inputSearch.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
// When user changed the Text
MainActivity.this.adapter.getFilter().filter(cs);
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
// TODO Auto-generated method stub
}
@Override
public void afterTextChanged(Editable arg0) {
// TODO Auto-generated method stub
}
});
}
}
activity_main.xml中
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<!-- Editext for Search -->
<EditText android:id="@+id/inputSearch"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="Search products.."
android:inputType="textVisiblePassword"/>
<!-- List View -->
<ListView
android:id="@+id/list_view"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
list_item.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" >
<!-- Single ListItem -->
<!-- Product Name -->
<TextView android:id="@+id/product_name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="10dip"
android:textSize="16dip"
android:textStyle="bold"/>
</LinearLayout>