我是Android程序员的新手。最近,我尝试在android应用程序中使用google map v2制作项目,但是我得到了很多错误(我已经将google play服务添加到我的库中,并且在这里找到了类似的主题,但是没有解决我的问题)。请看我的日志猫吼:
03-22 13:52:29.331: E/AndroidRuntime(17708): FATAL EXCEPTION: main 03-22 13:52:29.331: E/AndroidRuntime(17708): java.lang.RuntimeException: Unable to resume activity {com.yai.testmap/com.yai.testmap.MainActivity}: java.lang.NullPointerException 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2613) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2641) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2127) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.ActivityThread.access$600(ActivityThread.java:140) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.os.Handler.dispatchMessage(Handler.java:99) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.os.Looper.loop(Looper.java:137) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.ActivityThread.main(ActivityThread.java:4895) 03-22 13:52:29.331: E/AndroidRuntime(17708): at java.lang.reflect.Method.invokeNative(Native Method) 03-22 13:52:29.331: E/AndroidRuntime(17708): at java.lang.reflect.Method.invoke(Method.java:511) 03-22 13:52:29.331: E/AndroidRuntime(17708): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994) 03-22 13:52:29.331: E/AndroidRuntime(17708): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761) 03-22 13:52:29.331: E/AndroidRuntime(17708): at dalvik.system.NativeStart.main(Native Method) 03-22 13:52:29.331: E/AndroidRuntime(17708): Caused by: java.lang.NullPointerException 03-22 13:52:29.331: E/AndroidRuntime(17708): at com.yai.testmap.MainActivity.setUpMapIfNeeded(MainActivity.java:93) 03-22 13:52:29.331: E/AndroidRuntime(17708): at com.yai.testmap.MainActivity.onResume(MainActivity.java:187) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1199) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.Activity.performResume(Activity.java:5237) 03-22 13:52:29.331: E/AndroidRuntime(17708): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2603) 03-22 13:52:29.331: E/AndroidRuntime(17708): ... 12 more
my mainactivity.java:
package com.yai.testmap; import android.support.v7.app.ActionBarActivity; import android.support.v4.app.Fragment; import android.os.Bundle; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; /* FOR ERROR REPPORT */ import android.util.Log; /* IMPORT FOR DROPDOWNLIST USED THIS PROJECT */ import android.widget.CheckBox; import android.widget.Spinner; import android.widget.Toast; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.AdapterView.OnItemSelectedListener; /* IMPORT FOR GOOGLE MAP */ import com.google.android.gms.maps.GoogleMap; import com.google.android.gms.maps.SupportMapFragment; /* FOR GOOGLE MAP TYPE */ import static com.google.android.gms.maps.GoogleMap.MAP_TYPE_HYBRID; import static com.google.android.gms.maps.GoogleMap.MAP_TYPE_NONE; import static com.google.android.gms.maps.GoogleMap.MAP_TYPE_NORMAL; import static com.google.android.gms.maps.GoogleMap.MAP_TYPE_SATELLITE; import static com.google.android.gms.maps.GoogleMap.MAP_TYPE_TERRAIN; class PlaceholderFragment extends Fragment implements OnItemSelectedListener{ private GoogleMap mGoogleMap; private CheckBox mTrafficCheckbox, mLocationCheckbox, mBuildingCheckbox, mIndoorCheckbox; public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); Spinner spinner = (Spinner) rootView.findViewById(R.id.spinnerOption); ArrayAdapter adapter = ArrayAdapter.createFromResource(getActivity(), R.array.spinner_option_string, android.R.layout.simple_spinner_item); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner.setAdapter(adapter); spinner.setOnItemSelectedListener((OnItemSelectedListener) getActivity()); mTrafficCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_traffic); mLocationCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_location); mBuildingCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_building); mIndoorCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_indoor); return rootView; } @Override public void onItemSelected(AdapterView parent, View view, int position, long id) { // TODO Auto-generated method stub } @Override public void onNothingSelected(AdapterView parent) { // TODO Auto-generated method stub } } public class MainActivity extends ActionBarActivity implements OnItemSelectedListener { private GoogleMap mGoogleMap; private CheckBox mTrafficCheckbox, mLocationCheckbox, mBuildingCheckbox, mIndoorCheckbox; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if (savedInstanceState == null) { getSupportFragmentManager().beginTransaction() .add(R.id.container, new PlaceholderFragment()).commit(); } } private void setUpMapIfNeeded(){ if(mGoogleMap == null){ mGoogleMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap(); } } private boolean checkReady(){ if(mGoogleMap == null){ Toast.makeText(this, R.string.map_not_ready, Toast.LENGTH_SHORT).show(); return false; } return true; } private void updateTraffic(){ if(!checkReady()){ return; } mGoogleMap.setTrafficEnabled(mTrafficCheckbox.isChecked()); } public void onTrafficToggled(View view){ updateTraffic(); } private void updateLocation(){ if(!checkReady()){ return; } mGoogleMap.setMyLocationEnabled(mLocationCheckbox.isChecked()); } public void onLocationToggled(View view){ updateLocation(); } private void updateBuilding(){ if(!checkReady()){ return; } mGoogleMap.setBuildingsEnabled(mBuildingCheckbox.isChecked()); } public void onBuildingToggled(View view){ updateBuilding(); } private void updateIndoor(){ if(!checkReady()){ return; } mGoogleMap.setIndoorEnabled(mIndoorCheckbox.isChecked()); } public void onIndoorToggled(View view){ updateIndoor(); } @Override public void onItemSelected(AdapterView parent, View view, int position, long id){ setLayer((String) parent.getItemAtPosition(position)); } private void setLayer(String layerName){ if(!checkReady()){ return; } if(layerName.equals(getString(R.string.normal))){ mGoogleMap.setMapType(MAP_TYPE_NORMAL); } else if(layerName.equals(getString(R.string.hybrid))){ mGoogleMap.setMapType(MAP_TYPE_HYBRID); } else if(layerName.equals(getString(R.string.satellite))){ mGoogleMap.setMapType(MAP_TYPE_SATELLITE); } else if(layerName.equals(getString(R.string.terrain))){ mGoogleMap.setMapType(MAP_TYPE_TERRAIN); } else if(layerName.equals(getString(R.string.none_map))){ mGoogleMap.setMapType(MAP_TYPE_NONE); } else{ Log.i("LDA", "Error setting layer with name " + layerName); } } @Override public void onNothingSelected(AdapterView parent){ } @Override protected void onResume() { super.onResume(); setUpMapIfNeeded(); if (mGoogleMap != null) { updateTraffic(); updateLocation(); updateBuilding(); updateIndoor(); } } @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; } @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(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } /** * A placeholder fragment containing a simple view. */ public static class PlaceholderFragment extends Fragment { public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); return rootView; } } }
我在这里使用的是fragment,所以这里是fragment_main.xml:
<?xml version="1.0" encoding="utf-8" ?>
<Spinner
android:id="@+id/spinnerOption"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<CheckBox
android:id="@+id/checkbox_traffic"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="onTrafficToggled"
android:text="@string/traffic" />
<CheckBox
android:id="@+id/checkbox_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="onLocationToggled"
android:text="@string/location" />
<CheckBox
android:id="@+id/checkbox_building"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="onBuildingsToggled"
android:checked="true"
android:text="@string/building" />
<CheckBox
android:id="@+id/checkbox_indoor"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="onIndoorToggled"
android:checked="true"
android:text="@string/indoor" />
</LinearLayout>
</RelativeLayout>
还有我的舱单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.yai.testmap"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="9"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-feature
android:glEsVersion="0x00020000"
android:required="true"
/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version"
/>
<activity
android:name="com.yai.testmap.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="SUPER SCREET CODE"
/>
</application>
</manifest>
这里是我的activity_main.xml:
<FrameLayout 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.yai.testmap.MainActivity"
tools:ignore="MergeRootFrame" />
我对我的旋转器和函数setUpMapIfNeeded()很好奇,因为当我注释代码的那一部分时,我的应用程序就可以工作了。我错过了什么?知道吗?多谢。
试试这个..
将旋转器
和所有复选框
从MainActivity
删除到PlaceholderFragment
,如下所示
public static class PlaceholderFragment extends Fragment implements OnItemSelectedListener{
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
Spinner spinner = (Spinner) rootView.findViewById(R.id.spinnerOption);
ArrayAdapter adapter = ArrayAdapter.createFromResource(getActivity(), R.array.spinner_option_string, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
spinner.setOnItemSelectedListener(getActivity());
mTrafficCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_traffic);
mLocationCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_location);
mBuildingCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_building);
mIndoorCheckbox = (CheckBox) rootView.findViewById(R.id.checkbox_indoor);
return rootView;
}
}
而且
@Override
protected void onCreate(Bundle savedInstanceState) {
/* CREATE OPTION FOR DROPDOWN LIST*/
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
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