-2
我主要在這方面尋求澄清和建議。在我正在處理的應用程序中，我設置了一個用於處理一些基本控件和文本的片段，並將必要的XML從活動佈局文件移到碎片佈局文件中，而不做任何更改。然而，現在當我運行應用程序時，我得到一個NULLPOINTEREXCEPTION，並且它似乎是在我的GameStart活動的第19行中導致的，當我嘗試通過其ID設置textView時。我沒有改變ID，只把它移到了片段佈局文件中，所以我有兩個問題：片段TextView ID造成崩潰
1）究竟是什麼原因發生了，因爲在我解決之前發生了類似的事情，但我沒有看它是在參考文檔發生在Android開發者
2）如何解決這一問題
以下的任何建議的原因是GameStart活動，與logcat中的錯誤，並且有問題的XML文件。在此先感謝，我花了2個小時試圖找到答案。
編輯的文件/ logcat的BELOW
logcat的：
12-04 13:48:06.322 826-826/com.saphiric.simproject E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.saphiric.simproject/com.saphiric.simproject.GameStart}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:109)
at com.saphiric.simproject.GameStart.<init>(GameStart.java:25)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1130)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
起始活性（當應用程序試圖啓動GameStart活動發生時的錯誤）：
package com.saphiric.simproject;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
public class TitleMenu extends ActionBarActivity {
public void startGame(View view){
Intent gameStart = new Intent(this, GameStart.class);
startActivity(gameStart);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActionBar actionBar = getSupportActionBar();
actionBar.hide();
setContentView(R.layout.activity_main_menu);
}
}
片段XML
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Relative layout to handle main interaction area -->
<RelativeLayout
android:id="@+id/relativeLayout"
android:layout_width="wrap_content"
android:layout_height="90dp"
android:layout_alignParentBottom="true"
android:background="@drawable/bg_text">
<TextView
android:id="@id/storyText"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:text="@string/story_opening_one"
android:textColor="@color/black" />
<Button
android:id="@+id/advanceButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@id/controlsFragment"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:background="@drawable/button_advance"
android:onClick="advanceGame" />
<Button
android:id="@+id/menuButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_below="@id/advanceButton"
android:background="@drawable/menu_button" />
</RelativeLayout>
</RelativeLayout>
片段類：
package com.saphiric.simproject;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* Created by Saphiric on 12/4/14.
*/
public class ControlsFragment extends Fragment {
/**
* Fragment Lifecycle Methods
*/
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
// Inflates the layout resource for the fragment
return inflater.inflate(R.layout.controls_fragment, container, false);
}
@Override
public void onPause(){
}
}
GameStart活動：
package com.saphiric.simproject;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
/**
* Created by Saphiric on 11/12/14.
*/
public class GameStart extends Activity{
/**
* Necessary activity variables
*/
protected int clickCount = 0;
TextView storyText = (TextView) findViewById(R.id.storyText);
/**
* Sets up and alert dialogue builder for making decisions
* This will need to be revised during production
*/
AlertDialog.Builder decisionTime = new AlertDialog.Builder(getApplicationContext());
/**
* Handles advancing non character based conversations at the beginning
* of the story.
* If the player decides to investigate the scream, then the app loads the appropriate activity, and the same with the
* decision to leave the scene.
*/
public void advanceGame(View view){
clickCount = clickCount + 1; // Increments clickCount by 1 per click
if (clickCount == 1){
storyText.setText(R.string.story_opening_two);
} else if(clickCount == 2){
decisionTime.setTitle("Decision Time!"); // Sets the title for the decision box
decisionTime.setCancelable(false); // Sets it so that the decision can not be cancelled.
decisionTime.setPositiveButton("Investigate",new DialogInterface.OnClickListener() { // Sets up the positive button
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
decisionTime.setNegativeButton("Leave the scene.",new DialogInterface.OnClickListener() { // Sets up the negative button
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
}
}
/**
* Android activity methods
* @param savedInstanceState is the apps savedInstanceState
*/
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_start);
}
}
GameStart佈局XML：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/bg_school_gate"
android:orientation="vertical">
<fragment
android:id="@+id/controlsFragment"
android:name="com.saphiric.simproject.ControlsFragment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:layout="@layout/controls_fragment" />
</RelativeLayout>
可能重複[什麼是空指針異常，以及如何解決它？]（http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how ）（**與小sugettion - 另一個問題與過早的findViewById調用**） – Selvin 2014-12-04 17:47:23