不能在另一個文件中使用另一個類的佈局

在我的小應用程序中，我試圖將視圖放入此活動的選項卡中。我第一次嘗試做的是設置視圖，其他類中的代碼（在其他文件中）中找到了一些代碼。這裏是構建選項卡並設置代碼的類。不能在另一個文件中使用另一個類的佈局

CreateCharacterTabsActivity.java

package com.androidGuy.DnDApp; 

import android.app.Activity; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.widget.LinearLayout; 
import android.widget.TabHost; 
import android.widget.TabHost.OnTabChangeListener; 
import android.widget.TableLayout; 
import android.content.Context; 
import android.content.Intent; 
import android.widget.TabHost.TabContentFactory; 

public class CreateCharacterTabsActivity extends Activity implements OnTabChangeListener { 
private TabHost tabHost; 
private TableLayout scoreTable; 
private LinearLayout raceLayout; 

private CharacterAbilityScoresActivity abilityScoresActivity; 

// Tab tags: got to love them. 
private static final String ABILITY_SCORES_TAB = "scores"; 
private static final String RACE_TAB = "race"; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.simple_layout); 

    // Set up them tabs. 
    tabHost = (TabHost) findViewById(android.R.id.tabhost); 
    // Set up the tabhost. 
    tabHost.setup(); 
    tabHost.setOnTabChangedListener(this); 
    scoreTable = (TableLayout) abilityScoresActivity.getAbilityScoreTable(); 
    raceLayout = (LinearLayout) findViewById(R.id.raceLayout); 



    // Add views to the tab host. 
     tabHost.addTab(tabHost.newTabSpec(ABILITY_SCORES_TAB).setIndicator("Scores").setContent(new TabContentFactory() { 
     public View createTabContent(String arg0) { 
      return scoreTable; 
     } 
    })); 

    tabHost.addTab(tabHost.newTabSpec(RACE_TAB).setIndicator("Races").setContent(new TabContentFactory() { 
     public View createTabContent(String arg1) { 
      return raceLayout; 
     } 
    })); 

    // I have heard this is a hack brought upon by a bug. 
    tabHost.setCurrentTab(1); 
    tabHost.setCurrentTab(0); 
} 


public void onTabChanged(String arg0) { 
    // TODO Auto-generated method stub 

} 

}

它得到其他代碼從這個類。

CharacterAbilityScoresActivity.java

package com.androidGuy.DnDApp; 

import android.app.Activity; 
import android.content.Context; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemSelectedListener; 
import android.widget.ArrayAdapter; 
import android.widget.Spinner; 
import android.widget.TableLayout; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.View; 

/* This is for character class scores, settings, and... Stuff. */ 
import com.androidGuy.DnDApp.CharacterData; 

public class CharacterAbilityScoresActivity extends Activity { 

CharacterData characterData = new CharacterData(); 

private Spinner strengthSpinner; 
private Spinner dexteritySpinner; 
private Spinner constitutionSpinner; 
private Spinner intelligenceSpinner; 
private Spinner wisdomSpinner; 
private Spinner charismaSpinner; 
private ArrayAdapter<?> adapter; 
private TableLayout abilityScoreTable; 

public TableLayout getAbilityScoreTable() { 
    return abilityScoreTable; 
} 

/* Le constructor. Set up all of the fields (the adapters and the spinner boxes) and return 
* a tabletLayout objects (or at least, I hope that's how it'll work). */ 
CharacterAbilityScoresActivity() { 

    final LayoutInflater Die_Fledermaus = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    abilityScoreTable = (TableLayout) Die_Fledermaus.inflate(R.layout.ability_score_spinners, null); 

    adapter = ArrayAdapter.createFromResource(Die_Fledermaus.getContext(), R.array.string_ability_scores, android.R.layout.simple_spinner_item); 
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 

    /* The ability score spinners */ 
    strengthSpinner = (Spinner) findViewById(R.id.StrengthSpinner); 

    strengthSpinner.setAdapter(adapter); 
    strengthSpinner.setOnItemSelectedListener(new OnItemSelectedListener() { 

      public void onItemSelected(AdapterView<?> arg0, View arg1, 
        int arg2, long arg3) { 
        characterData.setStrengthScore(getResources().getIntArray(R.array.ability_scores)[(int) strengthSpinner.getItemIdAtPosition(arg2)]); 
      } 

      public void onNothingSelected(AdapterView<?> arg0) { 

      } 

     }); 

    dexteritySpinner = (Spinner) findViewById(R.id.dexteritySpinner); 

    dexteritySpinner.setAdapter(adapter); 
    dexteritySpinner.setOnItemSelectedListener(new OnItemSelectedListener() { 

       public void onItemSelected(AdapterView<?> arg0, View arg1, 
         int arg2, long arg3) { 
         characterData.setDexterityScore(getResources().getIntArray(R.array.ability_scores)[(int) dexteritySpinner.getItemIdAtPosition(arg2)]); 

       } 

       public void onNothingSelected(AdapterView<?> arg0) { 

       } 

      }); 

    constitutionSpinner = (Spinner) findViewById(R.id.ConstitutionSpinner); 
    constitutionSpinner.setAdapter(adapter); 
    constitutionSpinner 
      .setOnItemSelectedListener(new OnItemSelectedListener() { 

       public void onItemSelected(AdapterView<?> parent, View view, 
         int pos, long id) { 
        characterData.setConstitutionScore(getResources().getIntArray(R.array.ability_scores)[(int) constitutionSpinner.getItemIdAtPosition(pos)]); 
       } 

       public void onNothingSelected(AdapterView<?> arg0) { 

       } 
      }); 

    intelligenceSpinner = (Spinner) findViewById(R.id.intelligenceSpinner); 
    intelligenceSpinner.setAdapter(adapter); 
    intelligenceSpinner 
      .setOnItemSelectedListener(new OnItemSelectedListener() { 

       public void onItemSelected(AdapterView<?> parent, View view, 
         int pos, long id) { 
        characterData.setIntelligenceScore(getResources().getIntArray(R.array.ability_scores)[(int) intelligenceSpinner.getItemIdAtPosition(pos)]); 
       } 

       public void onNothingSelected(AdapterView<?> arg0) { 

       } 
      }); 

    wisdomSpinner = (Spinner) findViewById(R.id.WisdomSpinner); 
    wisdomSpinner.setAdapter(adapter); 
    wisdomSpinner 
      .setOnItemSelectedListener(new OnItemSelectedListener() { 

       public void onItemSelected(AdapterView<?> arg0, View arg1, 
         int arg2, long arg3) { 
        characterData.setWisdomScore(getResources().getIntArray(R.array.ability_scores)[(int) wisdomSpinner.getItemIdAtPosition(arg2)]); 
       } 

       public void onNothingSelected(AdapterView<?> arg0) { 

       } 

      }); 

    charismaSpinner = (Spinner) findViewById(R.id.CharismaSpinner); 
    charismaSpinner.setAdapter(adapter); 
    charismaSpinner 
      .setOnItemSelectedListener(new OnItemSelectedListener() { 

       public void onItemSelected(AdapterView<?> arg0, View arg1, 
         int arg2, long arg3) { 
        characterData.setCharismaScore(getResources().getIntArray(R.array.ability_scores)[(int) charismaSpinner.getItemIdAtPosition(arg2)]); 
       } 

       public void onNothingSelected(AdapterView<?> arg0) { 

       } 

      }); 
    } 
}

什麼是假設發生在CharacterAbilityScoresActivity構造函數創建所有的旋轉框，併爲其指定適配器。然後我嘗試返回保存在createTabContent()方法CreateCharacterTabsActivity中的tableLayout。但是，會發生什麼錯誤發生在tabHost.setup()附近（這是堆棧跟蹤顯示錯誤發生的位置）。

只是爲了進一步幫助，這裏是堆棧跟蹤。

07-16 13:40:47.100: ERROR/AndroidRuntime(386): FATAL EXCEPTION: main 
07-16 13:40:47.100: ERROR/AndroidRuntime(386): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidGuy.DnDApp/com.androidGuy.DnDApp.CreateCharacterTabsActivity}: java.lang.NullPointerException 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.os.Handler.dispatchMessage(Handler.java:99) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.os.Looper.loop(Looper.java:123) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at java.lang.reflect.Method.invokeNative(Native Method) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at java.lang.reflect.Method.invoke(Method.java:507) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at dalvik.system.NativeStart.main(Native Method) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386): Caused by: java.lang.NullPointerException 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at com.androidGuy.DnDApp.CreateCharacterTabsActivity.onCreate(CreateCharacterTabsActivity.java:34) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 
07-16 13:40:47.100: ERROR/AndroidRuntime(386):  ... 11 more

來源

2011-07-16 Ertain

我認爲在你的第一個代碼塊中丟失的反引號是錯誤的;我刪除它，所以格式越來越好;）。更進一步：您應該嘗試刪除一些代碼（所有與錯誤無關的代碼），因此您只需要一個簡單的示例，並且實際上應該粘貼錯誤（stacktrace）。 – Nanne

雖然沒有堆棧跟蹤和代碼\ infty量，這看起來沙基：

setContentView(R.layout.simple_layout); 

// Set up them tabs. 
tabHost = (TabHost) findViewById(android.R.id.tabhost);

You'v一定要認識到，findViewById沒有找到任何XML隨機視圖，但在您的屏幕上找到視圖。

與ID tabhost的觀點是tabs.xml，而據我可以看到你只需要在屏幕上simple_layout，在這一點上變量tabHost將null。

所以這下一行：

tabHost.setup();

會給你一個nullpointerexception。

來源

2011-07-16 07:28:47 Nanne

感謝您的回答，Nanne。所以我應該設置一個更多的視圖佈局？或者只是改變tabs.xml文件？ – Ertain

你可以，但不必。你唯一不能做的就是在不在屏幕上的視圖（id）上使用'findviewbyid'。如果這是你需要的，你可以將它們添加到你正在查看的xml中，但是你也可以使用inflater來讀取一個使用'addview'的xml。 – Nanne

啊，好吧。所以我會誇大佈局，並嘗試使用「addview」。 – Ertain

不能在另一個文件中使用另一個類的佈局

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