无法在其他文件中使用其他类的布局

时间：2011-07-16 07:12:36

标签： java android xml layout

在我的小应用程序中，我正在尝试将视图放入此活动的选项卡中。我首先尝试做的是设置视图，其中一些代码可以在其他类中找到（在其他文件中）。这是构建选项卡并设置代码的类。

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

}

}

它从这个类中获取其他代码。

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) {

                }

            });
    }   
}

假设要发生的是CharacterAbilityScoresActivity中的构造函数创建所有旋转框并为其分配适配器。然后我尝试返回tableLayout，它将createTabContent()方法保存在CreateCharacterTabsActivity中。但是，会发生在tabHost.setup()周围发生错误（堆栈跟踪表示错误发生的地方）。

[edit]为了进一步提供帮助，这里是堆栈跟踪。

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

1 个答案:

答案 0 :(得分：1)

虽然没有堆栈跟踪和一些\ infty数量的代码，但这看起来很简单：

setContentView(R.layout.simple_layout);

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

您必须意识到findViewById在任何XML中都找不到随机视图，但在屏幕上查找视图。

由于ID为tabhost的视图位于tabs.xml中，并且据我所知，您在屏幕上只有simple_layout，此时变量tabHost将为{ {1}}。

下一行：

null

会给你一个tabHost.setup(); 。

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