调用onclick时，activitythread.java中的RuntimeException

Question

我正在调试我的应用程序，当它进入onclick时它失败了。它进入activitythread.java并抛出此异常：

catch (Exception e) {
            if (!mInstrumentation.onException(activity, e)) {
                throw new RuntimeException(
                    "Unable to start activity " + component
                    + ": " + e.toString(), e);
            }
        }

这是我的代码。它在第34行附近：

public class SignUPActivity extends Activity {
    LoginDataBaseAdapter loginDataBaseAdapter;
    EditText editTextUserName, editTextPassword, editTextConfirmPassword;
    Button btnCreateAccount;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);

        //get Instance of Database Adapter
        try {
            loginDataBaseAdapter = new LoginDataBaseAdapter(this);
            loginDataBaseAdapter = loginDataBaseAdapter.open();
        }
        catch(SQLException s1){

        }

        editTextUserName=(EditText)findViewById(R.id.editTextUserName);
        editTextPassword=(EditText)findViewById(R.id.editTextPassword);
        editTextConfirmPassword=(EditText)findViewById(R.id.editTextConfirmPassword);
editTextUserName.setText("");
editTextPassword.setText("");
editTextConfirmPassword.setText("");

        btnCreateAccount = (Button)findViewById(R.id.buttonCreateAccount);
        btnCreateAccount.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String userName = editTextUserName.getText().toString();
                String password = editTextPassword.getText().toString();
                String confirmPassword = editTextConfirmPassword.getText().toString();

                // check if any of the fields are vacant
                if (userName.equals("")||password.equals("")||confirmPassword.equals("")){
                    Toast.makeText(getApplicationContext(), "Field Vacant", Toast.LENGTH_LONG).show();
                    return;
                }
                if(!password.equals(confirmPassword)){
                    Toast.makeText(getApplicationContext(),"Password does not match", Toast.LENGTH_LONG).show();
                    return;
                }
                else{
                    //save the data in database
                    loginDataBaseAdapter.insertEntry(userName,password);
                    Toast.makeText(getApplicationContext(),"Account successfully created", Toast.LENGTH_LONG).show();
                }
            }
        });
    }
    @Override
    protected void onDestroy(){
        super.onDestroy();
        loginDataBaseAdapter.close();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_sign_up, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

当我在调试模式下运行时，它没有在logcat中提供任何内容。 这些是我迄今为止所看到的。

ActivityThread exception in Android? Android ActivityThread error Android application RuntimeException in ActivityThread failed to find some source?

09-09 22:03:17.547      825-825/com.example.andrewspiteri.fordsyncapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.andrewspiteri.fordsyncapp/com.example.andrewspiteri.fordsyncapp.SignUPActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5041)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.example.andrewspiteri.fordsyncapp.SignUPActivity.onCreate(SignUPActivity.java:37)
            at android.app.Activity.performCreate(Activity.java:5104)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5041)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
            at dalvik.system.NativeStart.main(Native Method)

我已经添加了建议的setText。

修改 login.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <EditText
        android:id="@+id/editTextUserNameToLogin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10">
        <requestFocus/>
    </EditText>
    <EditText
        android:id="@+id/editTextPasswordToLogin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPassword"
        android:hint="Password"/>
    <Button
        android:id="@+id/buttonSignIn"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Sign In"/>
</LinearLayout>