NullPointer异常onClick

Question

我的代码是：

public class Register extends Activity {

    // JSON Response node names
    private static String KEY_SUCCESS = "success";
    private static String KEY_UID = "uid";
    private static String KEY_FIRSTNAME = "fname";
    private static String KEY_LASTNAME = "lname";
    private static String KEY_USERNAME = "uname";
    private static String KEY_EMAIL = "email";
    private static String KEY_CREATED_AT = "created_at";
    private static String KEY_ERROR = "error";

    // Defining layout items
    EditText inputFirstName;
    EditText inputLastName;
    EditText inputUsername;
    EditText inputEmail;
    EditText inputPassword;
    Button btnRegister;
    TextView registerErrorMsg;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);

        // Defining all layout items
        inputFirstName = (EditText) findViewById(R.id.fname);
        inputLastName = (EditText) findViewById(R.id.lname);
        inputUsername = (EditText) findViewById(R.id.uname);
        inputPassword = (EditText) findViewById(R.id.pword);
        btnRegister = (Button) findViewById(R.id.register);
        registerErrorMsg = (TextView)findViewById(R.id.register_error);

        // Button which Switches back to the login screen on clicked
        Button login = (Button) findViewById(R.id.bktologin);
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(v.getContext(), LoginActivity.class);
                startActivityForResult(i, 0);
                finish();
            }
        });

        // Register Button click event. A toast is set to alert when the fields are empty
        // Another toast is set to alert Username must be 5 characters.
        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {



                if ((!inputUsername.getText().toString().equals("")) && (!inputPassword.getText().toString().equals("")) && (!inputFirstName.getText().toString().equals("")) && (!inputLastName.getText().toString().equals("")) && (!inputEmail.getText().toString().equals(""))) {
                    Log.e(KEY_ERROR, "Pride do kle4");
                    if (inputUsername.getText().toString().length() > 4) {
                        Log.e(KEY_ERROR, "Pride do kle2");
                        NetAsync (v);
                    }
                    else {
                        Log.e(KEY_ERROR, "Pride do kle3");
                        Toast.makeText(getApplicationContext(),
                                "Username should be minimum 5 characters", Toast.LENGTH_SHORT).show();
                    }
                } else {
                    Log.e(KEY_ERROR, "Pride do kle5");
                    Toast.makeText(getApplicationContext(),
                            "One or more fields are empty", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    // Async Task to check whether internet connection is working
    private class NetCheck extends AsyncTask<String, Void, Boolean> {
        private ProgressDialog nDialog;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            nDialog = new ProgressDialog(Register.this);
            nDialog.setMessage("Loadig...");
            nDialog.setTitle("Checking Network");
            nDialog.setIndeterminate(false);
            nDialog.setCancelable(true);
            nDialog.show();
        }

        @Override
        protected Boolean doInBackground(String... args) {
            // Gets current device state and checks for working internet connection by trying Google
            ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo netInfo = cm.getActiveNetworkInfo();
            if (netInfo != null && netInfo.isConnected()) {
                try {
                    URL url = new URL("http://www.google.com");
                    HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
                    urlc.setConnectTimeout(3000);
                    urlc.connect();
                    if (urlc.getResponseCode() == 200) {
                        return true;
                    }
                } catch (MalformedURLException e1) {
                    e1.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return false;
        }

        @Override
        protected void onPostExecute(Boolean th) {
            if (th == true) {
                nDialog.dismiss();
                new ProcessRegister().execute();
            } else {
                nDialog.dismiss();
                registerErrorMsg.setText("Error in Network Connection");
            }
        }
    }

我收到此错误：

08-30 17:11:41.155  26407-26407/com.knedl.testloginapp W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418adda0)
08-30 17:11:41.155  26407-26407/com.knedl.testloginapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.knedl.testloginapp, PID: 26407
    java.lang.NullPointerException
            at com.knedl.testloginapp.Register$2.onClick(Register.java:85)
            at android.view.View.performClick(View.java:4640)
            at android.view.View$PerformClick.run(View.java:19425)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5593)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

您的inputEmail似乎未初始化。

Answer 2

您忘记在以下代码中初始化inputEmail

 // Defining all layout items
        inputFirstName = (EditText) findViewById(R.id.fname);
        inputLastName = (EditText) findViewById(R.id.lname);
        inputUsername = (EditText) findViewById(R.id.uname);
        inputEmail = (EditText) findViewById(R.id.email); // this is the line you are forgetting
        inputPassword = (EditText) findViewById(R.id.pword);
        btnRegister = (Button) findViewById(R.id.register);