Question

按钮ID“btn_scansiona”我遇到问题，点击它后触发了以下追溯：

java.lang.IllegalStateException: Could not find method onButtonClick(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton with id 'btn_scansiona'
                                                                           at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:325)
                                                                           at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284)
                                                                           at android.view.View.performClick(View.java:4780)
                                                                           at android.view.View$PerformClick.run(View.java:19866)
                                                                           at android.os.Handler.handleCallback(Handler.java:739)
                                                                           at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                           at android.os.Looper.loop(Looper.java:135)
                                                                           at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                           at java.lang.reflect.Method.invoke(Native Method)
                                                                           at java.lang.reflect.Method.invoke(Method.java:372)
                                                                           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

fragment_scan.xml

<FrameLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.test.myapp.ScanFragment">


<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:text="keywords"
    android:id="@+id/textView3"
    android:layout_gravity="center_horizontal|top"
    android:textStyle="bold"
    android:layout_marginTop="40dp"
    android:textSize="20dp" />

<Button
    android:layout_width="200dp"
    android:layout_height="wrap_content"
    android:text="scansiona"
    android:id="@+id/btn_scansiona"
    android:layout_gravity="center_horizontal|bottom"
    android:textStyle="bold"
    android:layout_marginBottom="40dp"
    android:background="#ffaa00"
    android:onClick="onButtonClick" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Insert keywords"
    android:id="@+id/textSearch"
    android:layout_marginTop="80dp"
    android:layout_gravity="center_horizontal|top"
    android:enabled="true"
    android:inputType="text"
    android:textColor="@color/abc_input_method_navigation_guard"
    android:textIsSelectable="false"
    android:textSize="20sp"
    android:textStyle="bold"
    android:selectAllOnFocus="false" />

ScanFragment.java

public class ScanFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";

// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;

private OnFragmentInteractionListener mListener;

public ScanFragment() {
    // Required empty public constructor
}

/**
 * Use this factory method to create a new instance of
 * this fragment using the provided parameters.
 *
 * @param param1 Parameter 1.
 * @param param2 Parameter 2.
 * @return A new instance of fragment ScanFragment.
 */
// TODO: Rename and change types and number of parameters
public static ScanFragment newInstance(String param1, String param2) {
    ScanFragment fragment = new ScanFragment();
    Bundle args = new Bundle();
    args.putString(ARG_PARAM1, param1);
    args.putString(ARG_PARAM2, param2);
    fragment.setArguments(args);
    return fragment;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);
    }

}



@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_scan, container, false);
}

// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
    if (mListener != null) {
        mListener.onFragmentInteraction(uri);
    }
}

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    try {
        mListener = (OnFragmentInteractionListener) context;
    } catch (ClassCastException e) {
        throw new ClassCastException(context.toString()
                + " must implement OnFragmentInteractionListener");
    }
}

@Override
public void onDetach() {
    super.onDetach();
    mListener = null;
}

//DB
private DbManager db=null;
private CursorAdapter adapter;
String date = new SimpleDateFormat("yyyy-MM-dd").format(new Date());

public void onButtonClick(View view){
    //do something when button is clicked.
    EditText txt=(EditText) view.findViewById(R.id.textSearch);
    if (txt.length()>0 && date.length()>0)
    {
        db.save(txt.getEditableText().toString(), date);
        adapter.changeCursor(db.query());
    }
}

}

如果我在MainActivity.java上声明方法“onButtonClick”，则以下回溯消失但我收到另一个关于“txt.length”的回溯不能为空。我的错误在哪里？谢谢丹尼尔

Answer 1

首先，onClick方法应该存在于父活动中，这就是为什么在您将代码移动到活动类时不会出现错误的原因

或

如果你想在片段中加入它，那么你必须初始化片段中的按钮并为它设置onClickListener，如下所示：

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout. fragment_scan, container, false); Button button = (Button) view.findViewById(R.id.btn_scansiona); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // do something } }); return view; }

并且你得到txt.length()不能为空错误，因为：

您已将txt定义为EditText，而不是其中的文字。您必须获取text并将其转换为String，如下所示：

txt.getText().toString()

然后你可以像这样进行正常处理：

txt.getText().toString().length()

Answer 2

移动您的方法＆＃39; onButtonClick＆＃39;对你的活动。

Answer 3

而不是在布局中定义ButtonClickListener方法。为什么不在代码中定义buttonClickListener ..

从布局和代码中删除android：onClick标记..使用

Button btnScan = view.findViewById(R.id.btn_scansiona
btnScan.onClickListener(.....){
//your rest code here....
}

欢迎Daniele

Answer 4

您必须在活动中定义该方法。

BTW我建议你使用Butterknife库，如果你想用这种方式编写你的代码。这很容易：

public class FancyFragment extends Fragment {

     @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
        View view = inflater.inflate(R.layout.fancy_fragment, container, false); 
        ButterKnife.bind(this, view);
        return view; 
    }

    @OnClick(R.id.submit) public void submit(View view) {
         // do something ... }
     }

   }

的build.gradle

compile 'com.jakewharton:butterknife:8.1.0'
apt 'com.jakewharton:butterknife-compile

Android - 找不到方法onButtonClick（查看）

4 个答案: