Android Studio - java.lang.IllegalStateException：無法找到按鈕的onClick方法

我試圖在單擊「button_addData」按鈕時執行「sendMessage（）」方法，但每次嘗試時，應用程序都會崩潰。目的是創建一個數據庫並將所有輸入的數據存儲在其中。下面是代碼片段：Android Studio - java.lang.IllegalStateException：無法找到按鈕的onClick方法

package com.example.rishi.ibplanner; 

import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.DatePicker; 
import android.widget.EditText; 
import android.widget.Spinner; 
import android.widget.Toast; 


import java.util.Calendar; 

public class EnterDataActivity extends AppCompatActivity { 

DatabaseHelper myDb; 
EditText editDescription, editDuration; 
Spinner spnPriority; 
Long deadlineDate; 
Button btnAddData; 

public long sendValue() { 
    DatePicker spnDatePicker = (DatePicker) findViewById(R.id.datepicker_deadline); 
    int day = spnDatePicker.getDayOfMonth(); 
    int month = spnDatePicker.getMonth(); 
    int year = spnDatePicker.getYear(); 

    Calendar thatDay = Calendar.getInstance(); 
    thatDay.set(Calendar.DAY_OF_MONTH, day); 
    thatDay.set(Calendar.MONTH, month); // 0-11 so 1 less 
    thatDay.set(Calendar.YEAR, year); 

    Calendar today = Calendar.getInstance(); 

    long diff = today.getTimeInMillis() - thatDay.getTimeInMillis(); //result in millis 
    long days = diff/(24 * 60 * 60 * 1000); //conversion into days 
    return days; 
} 
    // Button to proceed 
    public void sendMessage(View view) { 



     myDb = new DatabaseHelper(this); 

     editDescription = (EditText)findViewById(R.id.edit_description); 
     editDuration = (EditText)findViewById(R.id.edit_duration); 
     spnPriority = (Spinner)findViewById(R.id.priority_spinner); 

     deadlineDate = sendValue(); 

     btnAddData = (Button)findViewById(R.id.button_addData); 
     addData(); 
} 




public void addData() { 
    btnAddData.setOnClickListener(
      new View.OnClickListener() { 
       @Override 
       public void onClick (View v) { 
        boolean isInserted = myDb.insertData(editDescription.getText().toString(), 
          editDuration.getText().toString(), 
          spnPriority.getSelectedItem().toString(), 
          deadlineDate.toString()); 
        if (isInserted = true) 
         Toast.makeText(EnterDataActivity.this, "Data Inserted", Toast.LENGTH_LONG).show(); 
        else 
         Toast.makeText(EnterDataActivity.this, "Data not Inserted", Toast.LENGTH_LONG).show(); 
       } 
      } 
    ); 
} 

public void cancelActivity (View view) { 
    onBackPressed(); 
}

}

和XML，只是按鍵，就是：

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
tools:context="com.example.rishi.ibplanner.EnterDataActivity"> 

<Button 
    android:id="@+id/button_addData" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentBottom="true" 
    android:layout_centerHorizontal="true" 
    android:layout_marginBottom="12dp" 
    android:onClick="sendMessage" 
    android:text="@string/add" /> 

</RelativeLayout>

而且我收到了logcat的錯誤是：

java.lang.IllegalStateException: Could not find method sendMessage[EnterDataActivity](View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton with id 'button_addData' 
                      at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:327) 
                      at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284) 
                      at android.view.View.performClick(View.java:5637) 
                      at android.view.View$PerformClick.run(View.java:22429) 
                      at android.os.Handler.handleCallback(Handler.java:751) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:154) 
                      at android.app.ActivityThread.main(ActivityThread.java:6119) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

來源

2017-03-23 Rishi

能告訴那裏的OnCreate代碼編寫的代碼片段，也沒有必要添加該按鈕聽衆，你已經通過XML指定它onclick屬性所以從addData中刪除監聽器 –

當您啓動應用程序時顯示什麼？按鈕是否出現？因爲您不會在活動中膨脹您的XML文件，所以XML無法導航到sendMessage（）方法。

您應該添加下列到你的活動：

this.setContentView(R.layout.your_layout)

來源

2017-03-23 15:47:00

Android Studio - java.lang.IllegalStateException：無法找到按鈕的onClick方法

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