Android 错误：空指针异常
我在运行gradle时遇到了一个错误，但我不知道问题出在哪里 请帮帮我 这是活动代码Android 错误：空指针异常,android,nullpointerexception,Android,Nullpointerexception,我在运行gradle时遇到了一个错误，但我不知道问题出在哪里 请帮帮我 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.u
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();
}
}
可能的解决方案如下：
- 检查gradle版本和您以前成功的android项目，或者尝试从头开始重新安装gradle（如果这是第一个项目）
- 如果gradle没有问题，请清理项目并重新构建项目
- 尝试在代码上创建断点，在这里声明和定义变量，在调试模式下运行应用程序，并检查变量为NULL的位置
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();
您已映射inputemail两次…您的id映射不正确…而不是inputemail=（EditText）findViewById（R.id.email）；您必须传递inputEmail=（EditText）findViewById（R.id.edittext4）；感谢您对这个错误的处理：）在这里使用修剪方法是错误的吗？
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'
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();
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();
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);