按钮不起作用。继续强制关闭应用程序[关闭]

Posted 2023-05-06

【中文标题】按钮不起作用。继续强制关闭应用程序[关闭]

【英文标题】：Button not working. Keeps on forcing app close [closed]

【发布时间】：2015-02-04 08:17:30

【问题描述】：

每当我将代码（按钮）插入片段时，应用程序都会强制关闭。我制作了一个 xml 文件，并在片段 java 中调用它，但它有一个适配器，在我的 xml 中，我使用 framelayout 将按钮放在页面的最底部。我也尝试使用页脚，但我得到了同样的错误。有谁知道如何解决这个问题？谢谢:)

XML 文件

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/takeQuiz"
android:orientation="horizontal"
android:background="@drawable/bg_linux_commands"
android:layout_
android:layout_>

<LinearLayout
android:layout_
android:layout_
android:layout_gravity="center"
android:orientation="horizontal">

<ListView android:id="@id/android:list"
           android:layout_
           android:layout_
           android:layout_marginTop="125dp"/>

</LinearLayout>


<LinearLayout 
android:layout_ 
android:id="@+id/linearLayout" 
android:layout_ 
android:gravity="center" 
android:layout_gravity="bottom">  

    <Button
        android:id="@+id/buttonTest"
        android:layout_wrap_content"
        android:gravity="center"
        android:text="@string/test" >
    </Button>

</LinearLayout>
</FrameLayout>

片段 JAVA

public class LinuxCommands extends ListFragment
String classes[] =  "File Managing System", "Scripting and Text Processing","Process and System Utility",
        "System Information Commands","Archival and Comparison Commands","Command Shells";

@SuppressLint("InflateParams")
@Override
public void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);

    // ActionBar
    ActionBar mActionBar = getActivity().getActionBar();
    mActionBar.setDisplayShowHomeEnabled(true);
    mActionBar.setDisplayShowTitleEnabled(false);
    LayoutInflater mInflater = LayoutInflater.from(getActivity());

    View mCustomView = mInflater.inflate(R.layout.actionbar_ttg, null);
    TextView mTextView = (TextView) mCustomView.findViewById(R.id.actionbar_ttg);
    mTextView.setText("LINUX COMMANDS");
    Typeface custom_font = Typeface.createFromAsset(getActivity().getAssets(),
            "fonts/BRLNSR.TTF");
            mTextView.setTypeface(custom_font);

    mTextView.setTextSize(18);
    mTextView.setGravity(Gravity.CENTER_VERTICAL | Gravity.CENTER_HORIZONTAL);

    mActionBar.setCustomView(mCustomView);
    mActionBar.setDisplayShowCustomEnabled(true);

    //Button
    final Button button = (Button) getView().findViewById(R.id.buttonTest);
    button.setOnClickListener(new View.OnClickListener() 
        public void onClick(View v) 
            // Quiz

            Intent intent = new Intent (getActivity(), Terminal.class);
            startActivity(intent);
        
    );


    ListAdapter adapter = new ArrayAdapter<String>(getActivity(), 
            android.R.layout.simple_list_item_1,
            classes);

    // Setting the list adapter for the ListFragment 
    setListAdapter(adapter);


public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) 

    return inflater.inflate(R.layout.fragment_linux_comm, container, false);



@Override
  public void onListItemClick(ListView l, View v, int position, long id) 


    if(position == 0) 
        Intent intent = new Intent (getActivity(), FileManagingSystemList.class);
        startActivity(intent);  
    
    else if (position == 1)
        Intent intent = new Intent (getActivity(),ScriptingAndTextProcessingList.class);
        startActivity(intent);
    
    else if (position == 2)
        Intent intent = new Intent (getActivity(),ProcessAndSystemUtilityList.class);
        startActivity(intent);
    
    else if (position == 3)
        Intent intent = new Intent (getActivity(),SystemInformationCmdList.class);
        startActivity(intent);
    
    else if (position == 4)
        Intent intent = new Intent (getActivity(),ArchivalAndCompressionCmdList.class);
        startActivity(intent);
    
    else
        Intent intent = new Intent (getActivity(),CommandShellsList.class);
        startActivity(intent);
    


 

LOGCAT

12-06 11:50:54.069: E/AndroidRuntime(26672): FATAL EXCEPTION: main
12-06 11:50:54.069: E/AndroidRuntime(26672): java.lang.NullPointerException
12-06 11:50:54.069: E/AndroidRuntime(26672):    at com.example.ttg.fragment.LinuxCommands.onCreate(LinuxCommands.java:56)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.app.BackStackRecord.run(BackStackRecord.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.app.FragmentManagerImpl$1.run(FragmentManager.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.os.Handler.handleCallback(Handler.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.os.Handler.dispatchMessage(Handler.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.os.Looper.loop(Looper.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at android.app.ActivityThread.main(ActivityThread.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at java.lang.reflect.Method.invokeNative(Native Method)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at java.lang.reflect.Method.invoke(Method.java:511)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
12-06 11:50:54.069: E/AndroidRuntime(26672):    at dalvik.system.NativeStart.main(Native Method)

【问题讨论】：

java.lang.NullPointerException at com.example.ttg.fragment.LinuxCommands.onCreate(LinuxCommands.java:56)

您应该在onCreateView() 方法中膨胀和初始化您的布局，而不是onCreate()。你想在膨胀的视图上调用findViewById()。

所以按钮应该在onCreateView()里面？

【参考方案1】：

在 Fragment 中你应该使用onCreateView() 方法。

@Override
    public View onCreateView(LayoutInflater inflater,ViewGroup container, Bundle args) 



root = inflater.inflate(R.layout.schedule_fragment, container, false);

startButton = (Button)root.findViewById(R.id.button);


        startButton.setOnClickListener(new OnClickListener() 
            @Override
            public void onClick(View v) 
                // your code.
            
        );
    return root;
    

【讨论】：

@NikkodelValle 你应该接受给定的答案。

@Ankit Sharma 请在发布答案之前做好格式化。下次注意了

我正在投票，但我没有足够的 repu