我是android新手。我创建了简单的应用程序，其中包含自动完成文本字段。我写了一些代码但不幸的是，当我运行时应用程序停止了。没有错误，我如何解决...
请任何人帮忙！
我的代码：
Mainactivity.java
package com.h2o;
import android.app.Activity;
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.Locale;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.location.Address;
import android.location.Geocoder;
import android.support.v4.app.DialogFragment;
import android.os.Bundle;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.res.Configuration;
import android.support.annotation.Nullable;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends FragmentActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
CustomDrawerAdapter adapter;
List<DrawerItem> dataList;
EditText mEdit;
private String[] states;
private Spinner spinner;
AutoCompleteTextView autoTextView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String[] city= getResources().getStringArray(R.array.city);
autoTextView = (AutoCompleteTextView) findViewById(R.id.city_autoCompleteTextView);
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,city);
autoTextView.setThreshold(1);
autoTextView.setAdapter(arrayAdapter);
// Initializing
dataList = new ArrayList<DrawerItem>();
mTitle = mDrawerTitle = getTitle();
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow,
GravityCompat.START);
// Add Drawer Item to dataList
dataList.add(new DrawerItem(true)); // adding a spinner to the list - 0
dataList.add(new DrawerItem("Wallet")); // adding a header to the list - 1
dataList.add(new DrawerItem("Balance", R.drawable.ic_balance)); // - 2
dataList.add(new DrawerItem("Profile"));// adding a header to the list - 3
dataList.add(new DrawerItem("Personal", R.drawable.ic_account));
dataList.add(new DrawerItem("Work", R.drawable.ic_account));
dataList.add(new DrawerItem("Address", R.drawable.ic_account));
dataList.add(new DrawerItem("Vehicle", R.drawable.ic_car));
dataList.add(new DrawerItem("Preference", R.drawable.ic_pref));
dataList.add(new DrawerItem("Other Option")); // adding a header to the list
dataList.add(new DrawerItem("About", R.drawable.ic_action_about));
dataList.add(new DrawerItem("Settings", R.drawable.ic_action_settings));
dataList.add(new DrawerItem("Help", R.drawable.ic_action_help));
adapter = new CustomDrawerAdapter(this, R.layout.custom_drawer_item,
dataList);
mDrawerList.setAdapter(adapter);
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.ic_drawer, R.string.drawer_open,
R.string.drawer_close) {
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
invalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle(mDrawerTitle);
invalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
}
//Calendar picker
public void selectDate(View view) {
DialogFragment newFragment = new SelectDateFragment();
newFragment.show(getSupportFragmentManager(), "DatePicker");
}
public void populateSetDate(int year, int month, int day) {
mEdit = (EditText)findViewById(R.id.dobText);
mEdit.setText(month + "/" + day + "/" + year);
}
public class SelectDateFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener
{
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Calendar calendar = Calendar.getInstance();
int yy = calendar.get(Calendar.YEAR);
int mm = calendar.get(Calendar.MONTH);
int dd = calendar.get(Calendar.DAY_OF_MONTH);
return new DatePickerDialog(getActivity(), this, yy, mm, dd);
}
public void onDateSet(DatePicker view, int yy, int mm, int dd) {
populateSetDate(yy, mm + 1, dd);
}
}
//Spinner
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void SelectItem(String item, int possition) {
Fragment fragment = null;
Bundle args = new Bundle();
switch(item) {
case "Balance": fragment = new BalanceFragment(); break;
case "Personal": fragment = new PersonalFragment(); break;
case "Work": fragment = new WorkFragment(); break;
case "Address": fragment = new AddressFragment(); break;
case "Vehicle": fragment = new VehicleFragment(); break;
case "Preference": fragment = new PreferenceFragment(); break;
case "About": fragment = new AboutFragment(); break;
case "Settings": fragment = new SettingsFragment(); break;
case "Help": fragment = new HelpFragment(); break;
default: fragment = new DefaultFragment(); break;
}
fragment.setArguments(args);
FragmentManager frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, fragment)
.commit();
mDrawerList.setItemChecked(possition, true);
setTitle(dataList.get(possition).getItemName());
mDrawerLayout.closeDrawer(mDrawerList);
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggles
mDrawerToggle.onConfigurationChanged(newConfig);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// The action bar home/up action should open or close the drawer.
// ActionBarDrawerToggle will take care of this.
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
return false;
}
private class DrawerItemClickListener implements
ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
if (dataList.get(position).getTitle() == null) {
SelectItem(dataList.get(position).getItemName(), position);
}
}
}
}
log cat：
06-03 12:23:32.446 2843-2843/? I/art﹕ Not late-enabling -Xcheck:jni (already on)
06-03 12:23:32.637 2843-2843/com.h2o D/AndroidRuntime﹕ Shutting down VM
06-03 12:23:32.638 2843-2843/com.h2o E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.h2o, PID: 2843
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.h2o/com.h2o.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.AutoCompleteTextView.setThreshold(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.AutoCompleteTextView.setThreshold(int)' on a null object reference
at com.h2o.MainActivity.onCreate(MainActivity.java:73)
at android.app.Activity.performCreate(Activity.java:5937)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Layout file
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="1">
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:weightSum="1">
<TextView
android:layout_width="wrap_content"
android:layout_height="40dp"
android:text="Address Details"
android:id="@+id/address"
android:textColor="#ff000000"
android:textSize="20dp"
android:layout_marginLeft="10dp"
android:gravity="center" />
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="1"
android:layout_weight="0.03">
<TextView
android:layout_width="wrap_content"
android:layout_height="33dp"
android:text="Tag Address"
android:id="@+id/residential"
android:textColor="#ff000000"
android:layout_marginLeft="10dp"
android:layout_gravity="center"
android:gravity="center" />
<RadioGroup
android:id="@+id/radioGroup"
android:layout_width="276dp"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_gravity="center"
android:weightSum="1">
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Home"
android:id="@+id/home"
android:layout_gravity="center"
android:textColor="#FF000000"
android:checked="false"
android:layout_weight="0.22"
android:layout_marginLeft="10dp" />
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Office"
android:id="@+id/office"
android:textColor="#FF000000"
android:checked="false"
android:layout_gravity="center" />
</RadioGroup>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="1"
android:layout_weight="0.06">
<TextView
android:layout_width="48dp"
android:layout_height="wrap_content"
android:text="Line 1"
android:id="@+id/address1"
android:textColor="#ff000000"
android:layout_marginLeft="10dp"
android:gravity="center" />
<EditText
android:layout_width="291dp"
android:layout_height="wrap_content"
android:inputType="textPostalAddress"
android:ems="10"
android:id="@+id/addressText"
android:layout_marginLeft="50dp"
android:textColor="#ff000000"
android:layout_weight="1.04" /> />
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="1"
android:layout_weight="0.06">
<TextView
android:layout_width="48dp"
android:layout_height="wrap_content"
android:text="Line 2"
android:id="@+id/address2"
android:textColor="#ff000000"
android:layout_marginLeft="10dp"
android:gravity="center" />
<EditText
android:layout_width="291dp"
android:layout_height="wrap_content"
android:inputType="textPostalAddress"
android:ems="10"
android:id="@+id/address2Text"
android:layout_marginLeft="50dp"
android:textColor="#ff000000"
android:layout_weight="1.04" /> />
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="1"
android:layout_weight="0.06">
<TextView
android:layout_width="48dp"
android:layout_height="wrap_content"
android:text="City"
android:id="@+id/city"
android:textColor="#ff000000"
android:layout_marginLeft="5dp"
android:gravity="center"
android:layout_gravity="center" />
<AutoCompleteTextView
android:layout_width="112dp"
android:layout_height="wrap_content"
android:id="@+id/city_autoCompleteTextView"
android:ems="10"
android:layout_gravity="center" />
<TextView
android:layout_width="wrap_content"
android:layout_height="33dp"
android:text="Zipcode"
android:id="@+id/zipcode"
android:textColor="#ff000000"
android:layout_marginLeft="10dp"
android:layout_gravity="center"
android:gravity="center" />
<EditText
android:layout_width="291dp"
android:layout_height="wrap_content"
android:inputType="number"
android:ems="10"
android:id="@+id/zipcodeText"
android:layout_marginLeft="10dp"
android:textColor="#ff000000"
android:layout_weight="1.04" /> />
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="50dp"
android:weightSum="1"
android:layout_weight="0.09">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Country"
android:id="@+id/country"
android:textColor="#ff000000"
android:layout_marginLeft="10dp"
android:layout_gravity="center" />
<Spinner
android:layout_width="75dp"
android:layout_height="31dp"
android:id="@+id/countrySpinner"
android:entries="@array/country_list"
android:layout_marginLeft="40dp"
android:spinnerMode="dropdown"
android:outlineProvider="bounds"
android:layout_gravity="center" />
<TextView
android:layout_width="51dp"
android:layout_height="match_parent"
android:text="State"
android:id="@+id/state"
android:textColor="#ff000000"
android:layout_marginLeft="10dp"
android:layout_gravity="center"
android:gravity="center" />
<Spinner
android:layout_width="75dp"
android:layout_height="31dp"
android:id="@+id/stateSpinner"
android:entries="@array/state_list"
android:spinnerMode="dropdown"
android:outlineProvider="bounds"
android:layout_weight="0.10"
android:layout_gravity="center"
android:layout_marginLeft="10dp" />
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="1"
android:layout_weight="0.06">
<TextView
android:layout_width="wrap_content"
android:layout_height="33dp"
android:text="Landmark"
android:id="@+id/landmark"
android:textColor="#ff000000"
android:layout_marginLeft="10dp"
android:layout_gravity="center"
android:gravity="center" />
<EditText
android:layout_width="291dp"
android:layout_height="wrap_content"
android:inputType="textPostalAddress"
android:ems="10"
android:id="@+id/landmarkText"
android:layout_marginLeft="40dp"
android:textColor="#ff000000"
android:layout_weight="1.04" /> />
</LinearLayout>
</LinearLayout>
感谢您提前!!
答案 0 :(得分：1)
检查布局 activity_main 文件
中下方行的IDautoTextView = (AutoCompleteTextView) findViewById(R.id.city_autoCompleteTextView);
此处autoTextView提供 null 。