Question

我想通过sql创建登录按钮。当我运行应用程序时，我遇到了一个onclick错误：

Sub NewButton()
Dim wb As Workbook
Dim wb2 As Workbook
Dim ws As Worksheet
Dim ws2 As Worksheet

Set wb = ThisWorkbook
Set ws = wb.Worksheets("Sheet 1")
Set wb2 = Workbooks.Open("File Directory of second workbook")
Set ws2 = wb2.Worksheets("Sheet 1")

   ws.Range("A:I") = ws2.Range("A:I").Value

End Sub

这是我的onclick代码：

Process: com.example.mosab.hostlent, PID: 31057
 java.lang.IllegalStateException: Could not execute method for android:onClick
     at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
     at android.view.View.performClick(View.java:5609)
     at android.view.View$PerformClick.run(View.java:22263)
     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:6077)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
  Caused by: java.lang.reflect.InvocationTargetException
     at java.lang.reflect.Method.invoke(Native Method)
     at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
     at android.view.View.performClick(View.java:5609) 
     at android.view.View$PerformClick.run(View.java:22263) 
     at android.os.Handler.handleCallback(Handler.java:751) 
     at android.os.Handler.dispatchMessage(Handler.java:95) 
     at android.os.Looper.loop(Looper.java:154) 
     at android.app.ActivityThread.main(ActivityThread.java:6077) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
     at com.example.mosab.hostlent.login.loginon(login.java:92)
     at java.lang.reflect.Method.invoke(Native Method) 
     at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
     at android.view.View.performClick(View.java:5609) 
     at android.view.View$PerformClick.run(View.java:22263) 
     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:6077) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

这是我的xml文件：

 public void loginon(View v) {
    String Email = email.getText().toString().trim();
    String Password = password.getText().toString().trim();
    String type = "login";
    worker worker = new worker(this);
    worker.execute(type,Email,Password);
}

我的课程由onclick代码调用：

<ImageButton
            android:id="@+id/login"
            android:layout_width="205dp"
            android:layout_height="50dp"
            android:layout_gravity="center"
            android:adjustViewBounds="true"
            android:background="@color/hostlent"
            android:baselineAlignBottom="false"
            android:contextClickable="false"
            android:cropToPadding="false"
            android:keepScreenOn="false"
            android:nestedScrollingEnabled="false"
            android:onClick="loginon"
            android:saveEnabled="false"
            android:scaleType="fitCenter"
            app:srcCompat="@drawable/login"
            tools:layout_editor_absoluteX="86dp"
            tools:layout_editor_absoluteY="332dp" />

我将在清单文件中添加此代码：

public class worker extends AsyncTask<String,Void,String> {
Context context ;
AlertDialog alertDialog;
worker (Context context){
    Context ctx;
}
@Override
protected String doInBackground(String... params) {
    String type = params[0];
    String login_url = "http://192.168.1.239:8080/login.php";
    if (type.equals("login")){
        try {
            String email = params[1];
            String password = params[2];
            URL url = new URL(login_url);
            HttpsURLConnection httpsURLConnection = (HttpsURLConnection)url.openConnection();
            httpsURLConnection.setRequestMethod("post");
            httpsURLConnection.setDoOutput(true);
            httpsURLConnection.setDoInput(true);
            OutputStream outputStream = httpsURLConnection.getOutputStream();
            BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
            String post_data = URLEncoder.encode("email","UTF-8")+"="+URLEncoder.encode(email,"UTF-8")+"&"+URLEncoder.encode(password,"UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            InputStream inputStream = httpsURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream,"iso-8859-1"));
            String result="";
            String line="";
            while ((line=bufferedReader.readLine())!=null){
                result += line;
            }
            bufferedReader.close();
            inputStream.close();
            httpsURLConnection.disconnect();
            return result;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    return null;
}

@Override
protected void onPreExecute() {
    alertDialog=new AlertDialog.Builder(context).create();
    alertDialog.setTitle("login status");
}

@Override
protected void onPostExecute(String result) {
    alertDialog.setMessage(result);
    alertDialog.show();
}

@Override
protected void onProgressUpdate(Void... values) {
    super.onProgressUpdate(values);
}
}

你能帮我理解哪个是我的错误吗？

Answer 1

错误出现在以下两行之一

中

String Email = email.getText().toString().trim();
String Password = password.getText().toString().trim();

变量电子邮件或密码为空。您需要将这些变量设置为onCreate（）方法中的相应edittext字段。

如果仍然无法解决问题，请使用完整代码将问题更新为您的活动和布局文件xml。

错误“无法执行android的方法：onClick”

1 个答案: