错误：空指针异常

-1

我在运行gradle时遇到错误，但我不知道问题是什么请帮助我。错误：空指针异常

这是活动代码

package com.example.hnnhm.myapplication_new; 

import android.app.Activity; 
import android.app.ProgressDialog; 
import android.content.Intent; 
import android.net.Uri; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 

import com.android.volley.Request; 
import com.android.volley.Response; 
import com.android.volley.VolleyError; 
import com.android.volley.toolbox.StringRequest; 
import com.google.android.gms.appindexing.Action; 
import com.google.android.gms.appindexing.AppIndex; 
import com.google.android.gms.appindexing.Thing; 
import com.google.android.gms.common.api.GoogleApiClient; 

import org.json.JSONException; 
import org.json.JSONObject; 

import java.util.HashMap; 
import java.util.Map; 

public class SignupActivity extends Activity { 
    private static final String TAG = SignupActivity.class.getSimpleName(); 
    private Button btnRegister; 
    private Button btnLinkToLogin; 
    private EditText inputFullName; 
    private EditText inputEmail; 
    private EditText inputAge; 
    private EditText inputWeight; 
    private EditText inputExtra; 
    private EditText inputPassword; 
    private ProgressDialog pDialog; 
    private SessionManager session; 
    private SQLiteHandler db; 
    /** 
    * ATTENTION: This was auto-generated to implement the App Indexing API. 
    * See https://g.co/AppIndexing/AndroidStudio for more information. 
    */ 
    private GoogleApiClient client; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_signup); 

     inputFullName = (EditText) findViewById(R.id.editText); 
     inputEmail = (EditText) findViewById(R.id.email); 
     inputAge = (EditText) findViewById(R.id.editText2); 
     inputEmail = (EditText) findViewById(R.id.editText3); 
     inputExtra = (EditText) findViewById(R.id.editText6); 
     inputPassword = (EditText) findViewById(R.id.password); 
     btnRegister = (Button) findViewById(R.id.button); 
     btnLinkToLogin = (Button) findViewById(R.id.button2); 

     // Progress dialog 
     pDialog = new ProgressDialog(this); 
     pDialog.setCancelable(false); 

     // Session manager 
     session = new SessionManager(getApplicationContext()); 

     // SQLite database handler 
     db = new SQLiteHandler(getApplicationContext()); 

     // Check if user is already logged in or not 
     if (session.isLoggedIn()) { 
      // User is already logged in. Take him to main activity 
      Intent intent = new Intent(SignupActivity.this, 
        LoginActivity.class); 
      startActivity(intent); 
      finish(); 
     } 

     // Register Button Click event 
     btnRegister.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View view) { 
       String name = inputFullName.getText().toString().trim(); 
       String email = inputEmail.getText().toString().trim(); 
       String password = inputPassword.getText().toString().trim(); 
       String Age = inputAge.getText().toString().trim(); 
       String weight = inputWeight.getText().toString().trim(); 
       String Extra = inputExtra.getText().toString().trim(); 

       if (!name.isEmpty() && !email.isEmpty() && !password.isEmpty() && !Age.isEmpty()&& !weight.isEmpty()&& !Extra.isEmpty()) { 
        registerUser(name, email, password, Age , weight , Extra); 
       } else { 
        Toast.makeText(getApplicationContext(), 
          "Please enter your details!", Toast.LENGTH_LONG) 
          .show(); 
       } 
      } 
     }); 

     // Link to Login Screen 
     btnLinkToLogin.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View view) { 
       Intent i = new Intent(getApplicationContext(), 
         LoginActivity.class); 
       startActivity(i); 
       finish(); 
      } 
     }); 

     // ATTENTION: This was auto-generated to implement the App Indexing API. 
     // See https://g.co/AppIndexing/AndroidStudio for more information. 
     client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build(); 
    } 

    /** 
    * Function to store user in MySQL database will post params(tag, name, 
    * email, password) to register url 
    */ 
    private void registerUser(final String name, final String email, 
           final String password, final String Age, final String weight, final String Extra) { 
     // Tag used to cancel the request 
     String tag_string_req = "req_register"; 

     pDialog.setMessage("Registering ..."); 
     showDialog(); 

     StringRequest strReq = new StringRequest(Request.Method.POST, 
       AppConfig.URL_REGISTER, new Response.Listener<String>() { 

      @Override 
      public void onResponse(String response) { 
       Log.d(TAG, "Register Response: " + response.toString()); 
       hideDialog(); 

       try { 
        JSONObject jObj = new JSONObject(response); 
        boolean error = jObj.getBoolean("error"); 
        if (!error) { 
         // User successfully stored in MySQL 
         // Now store the user in sqlite 
         String uid = jObj.getString("uid"); 

         JSONObject user = jObj.getJSONObject("user"); 
         String name = user.getString("name"); 
         String email = user.getString("email"); 
         String created_at = user 
           .getString("created_at"); 

         // Inserting row in users table 
         db.addUser(name, email, uid, Age, weight,Extra); 

         Toast.makeText(getApplicationContext(), "User successfully registered. Try login now!", Toast.LENGTH_LONG).show(); 

         // Launch login activity 
         Intent intent = new Intent(
           SignupActivity.this, 
           LoginActivity.class); 
         startActivity(intent); 
         finish(); 
        } else { 

         // Error occurred in registration. Get the error 
         // message 
         String errorMsg = jObj.getString("error_msg"); 
         Toast.makeText(getApplicationContext(), 
           errorMsg, Toast.LENGTH_LONG).show(); 
        } 
       } catch (JSONException e) { 
        e.printStackTrace(); 
       } 

      } 
     }, new Response.ErrorListener() { 

      @Override 
      public void onErrorResponse(VolleyError error) { 
       Log.e(TAG, "Registration Error: " + error.getMessage()); 
       Toast.makeText(getApplicationContext(), 
         error.getMessage(), Toast.LENGTH_LONG).show(); 
       hideDialog(); 
      } 
     }) { 

      @Override 
      protected Map<String, String> getParams() { 
       // Posting params to register url 
       Map<String, String> params = new HashMap<String, String>(); 
       params.put("name", name); 
       params.put("email", email); 
       params.put("password", password); 

       return params; 
      } 

     }; 

     // Adding request to request queue 
     AppController.getInstance().addToRequestQueue(strReq, tag_string_req); 
    } 

    private void showDialog() { 
     if (!pDialog.isShowing()) 
      pDialog.show(); 
    } 

    private void hideDialog() { 
     if (pDialog.isShowing()) 
      pDialog.dismiss(); 
    } 

    /** 
    * ATTENTION: This was auto-generated to implement the App Indexing API. 
    * See https://g.co/AppIndexing/AndroidStudio for more information. 
    */ 
    public Action getIndexApiAction() { 
     Thing object = new Thing.Builder() 
       .setName("Register Page") // TODO: Define a title for the content shown. 
       // TODO: Make sure this auto-generated URL is correct. 
       .setUrl(Uri.parse("http://[ENTER-YOUR-URL-HERE]")) 
       .build(); 
     return new Action.Builder(Action.TYPE_VIEW) 
       .setObject(object) 
       .setActionStatus(Action.STATUS_TYPE_COMPLETED) 
       .build(); 
    } 

    @Override 
    public void onStart() { 
     super.onStart(); 

     // ATTENTION: This was auto-generated to implement the App Indexing API. 
     // See https://g.co/AppIndexing/AndroidStudio for more information. 
     client.connect(); 
     AppIndex.AppIndexApi.start(client, getIndexApiAction()); 
    } 

    @Override 
    public void onStop() { 
     super.onStop(); 

     // ATTENTION: This was auto-generated to implement the App Indexing API. 
     // See https://g.co/AppIndexing/AndroidStudio for more information. 
     AppIndex.AppIndexApi.end(client, getIndexApiAction()); 
     client.disconnect(); 
    } 
}

，这是该活动

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/activity_signup" 
    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.example.hnnhm.myapplication_new.SignupActivity"> 

    <TextView 
     android:text="Name:" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentTop="true" 
     android:id="@+id/textView3" 
     android:textSize="18sp" 
     android:textStyle="normal|bold" 
     android:textColor="@color/common_google_signin_btn_text_dark_focused" 
     android:layout_alignParentStart="true" /> 

    <TextView 
     android:text="Age:" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/textView4" 
     android:layout_below="@+id/editText" 
     android:layout_alignParentStart="true" 
     android:textStyle="normal|bold" 
     android:textSize="18sp" 
     android:textColor="@color/common_google_signin_btn_text_dark_focused" /> 

    <TextView 
     android:text="Email:" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_below="@+id/editText2" 
     android:layout_alignParentStart="true" 
     android:id="@+id/textView5" 
     android:textStyle="normal|bold" 
     android:textColor="@color/common_google_signin_btn_text_dark_focused" 
     android:textSize="18sp" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="textEmailAddress" 
     android:ems="10" 
     android:layout_below="@+id/textView5" 
     android:layout_alignEnd="@+id/editText2" 
     android:id="@+id/editText4" 
     android:text="Your Email" 
     android:textColor="@color/common_plus_signin_btn_text_dark_disabled" /> 

    <TextView 
     android:text="Password:" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/textView6" 
     android:textStyle="normal|bold" 
     android:textColor="@color/common_google_signin_btn_text_dark_focused" 
     android:textSize="18sp" 
     android:layout_below="@+id/editText4" 
     android:layout_alignParentStart="true" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="textPassword" 
     android:ems="10" 
     android:layout_below="@+id/textView6" 
     android:layout_alignParentStart="true" 
     android:id="@+id/editText5" 
     android:text="Password" 
     android:textColor="@color/common_plus_signin_btn_text_dark_disabled" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="number" 
     android:ems="10" 
     android:id="@+id/editText2" 
     android:textSize="18sp" 
     android:text="Your age" 
     android:textColor="@color/common_plus_signin_btn_text_dark_disabled" 
     android:layout_below="@+id/textView4" 
     android:layout_alignParentStart="true" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="textPersonName" 
     android:text="Your name" 
     android:ems="10" 
     android:id="@+id/editText" 
     android:textSize="18sp" 
     android:textColor="@color/common_plus_signin_btn_text_dark_disabled" 
     android:layout_below="@+id/textView3" 
     android:layout_alignParentStart="true" /> 

    <TextView 
     android:text="Weight:" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/textView9" 
     android:textSize="18sp" 
     android:textColor="@color/common_google_signin_btn_text_dark_focused" 
     android:textStyle="normal|bold" 
     android:layout_below="@+id/editText5" 
     android:layout_alignParentStart="true" /> 

    <Button 
     android:text="Login" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/button2" 
     android:layout_alignParentBottom="true" 
     android:layout_alignParentEnd="true" 
     android:layout_marginEnd="20dp" /> 

    <TextView 
     android:text="already a member?" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/textView8" 
     android:textAlignment="textStart" 
     android:textStyle="normal|bold" 
     android:layout_alignParentBottom="true" 
     android:layout_toStartOf="@+id/button2" /> 

    <Button 
     android:text="Signup" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/button" 
     android:layout_marginStart="11dp" 
     android:layout_alignParentBottom="true" 
     android:layout_alignParentStart="true" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="textPersonName" 
     android:text="Your weight" 
     android:ems="10" 
     android:layout_below="@+id/textView9" 
     android:layout_alignParentStart="true" 
     android:id="@+id/editText3" 
     android:textColor="@color/common_plus_signin_btn_text_dark_disabled" /> 

    <TextView 
     android:text="allergies and diseases:" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/textView7" 
     android:textStyle="normal|bold" 
     android:textSize="18sp" 
     android:textColor="@color/common_google_signin_btn_text_dark_focused" 
     android:layout_below="@+id/editText3" 
     android:layout_alignParentStart="true" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="textPersonName" 
     android:text="and allergies or chronic disease you have" 
     android:ems="10" 
     android:id="@+id/editText6" 
     android:textSize="18sp" 
     android:textColor="@color/common_plus_signin_btn_text_dark_disabled" 
     android:layout_below="@+id/textView7" 
     android:layout_alignParentStart="true" /> 

</RelativeLayout>

XML代码，这是运行gradle这个

E/AndroidRuntime: FATAL EXCEPTION: main 
        Process: com.example.hnnhm.myapplication_new, PID: 4329 
        java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference 
         at com.example.hnnhm.myapplication_new.SignupActivity$1.onClick(SignupActivity.java:86) 
         at android.view.View.performClick(View.java:5637) 
         at android.view.View$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) 
Disconnected from the target VM, address: 'localhost:8605', transport: 'socket'

来源

2017-04-22 haneen

已映射inputemail两次......你的ID映射是不正确......而不是inputEmail的=（EditText）findViewById（R.id.email）;你必须通过inputEmail =（EditText）findViewById（R.id.edittext4）; –

Change your mappings like this and it will solve your error. 
inputFullName = (EditText) findViewById(R.id.editText); 
     inputEmail = (EditText) findViewById(R.id.editText4); 
     inputAge = (EditText) findViewById(R.id.editText2); 
     inputWeight = (EditText) findViewById(R.id.editText3); 
     inputExtra = (EditText) findViewById(R.id.editText6); 
     inputPassword = (EditText) findViewById(R.id.editText5);

来源

2017-04-22 11:56:15

谢谢你为这个错误工作:) – haneen

当我收到错误

可能的解决方案可能是这样的：

查看以前成功的android项目的gradle版本，或者尝试从头开始重新安装gradle（如果这是第一个项目）。
清理您的项目，如果没有Gradle问题，重新构建项目。
尝试创建您的代码，你声明和定义的变量和运行调试模式应用程序并检查您的变量去NULL断点。

因为这些是我在我的项目上所做的尝试。

可能会有所帮助。

:) PEACE

来源

2017-04-22 11:46:13

改变一切：

  String name = inputFullName.getText().toString().trim(); 
      String email = inputEmail.getText().toString().trim(); 
      String password = inputPassword.getText().toString().trim(); 
      String Age = inputAge.getText().toString().trim(); 
      String weight = inputWeight.getText().toString().trim(); 
      String Extra = inputExtra.getText().toString().trim();

要

  String name = inputFullName.getText().toString(); 
      String email = inputEmail.getText().toString(); 
      String password = inputPassword.getText().toString(); 
      String Age = inputAge.getText().toString(); 
      String weight = inputWeight.getText().toString(); 
      String Extra = inputExtra.getText().toString();

来源

2017-04-22 11:47:28

这里使用trim方法是否为false？ – haneen

错误：空指针异常

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