Java 添加到我的项目中的新类使应用程序退出

我正试图解决它，但我做不到。几个小时前我发了帖子，有人给了我一些建议。但不幸的是，它不起作用。。 我在项目中添加了LoginActivity、BackgroundTask和RegisterActivity类。 在组合它们之前，该项目在包含php mysql connect时运行良好。 我不知道我该怎么办

这是LoginActivity代码

public class LoginActivity extends Activity {
    EditText ET_NAME,ET_PASS;
    String login_name,login_pass;

    @Override

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login_main);
        ET_NAME = (EditText)findViewById(R.id.user_name);
        ET_PASS = (EditText)findViewById(R.id.user_pass);
    }
    public void userReg(View view)
    {
        startActivity(new Intent(this,RegisterActivity.class));
    }
    public void userLogin(View view)
    {
        login_name = ET_NAME.getText().toString();
        login_pass = ET_PASS.getText().toString();
        String method = "login";
        BackgroundTask backgroundTask = new BackgroundTask(this);
        backgroundTask.execute(method,login_name,login_pass);
    }
}

public class RegisterActivity extends Activity {
    EditText ET_NAME, ET_USER_NAME, ET_USER_PASS;
    String name, user_name, user_pass;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.register_layout);
        ET_NAME = (EditText)findViewById(R.id.name);
        ET_USER_NAME = (EditText)findViewById(R.id.new_user_name);
        ET_USER_PASS = (EditText)findViewById(R.id.new_user_pass);
    }
    public void userReg(View view)
    {
        name = ET_NAME.getText().toString();
        user_name = ET_USER_NAME.getText().toString();
        user_pass = ET_USER_PASS.getText().toString();
        String method = "register";
        BackgroundTask backgroundTask = new BackgroundTask(this);
        backgroundTask.execute(method,name, user_name, user_pass);
    }

}

这是BackgroundTask.java

public class BackgroundTask extends AsyncTask<String,Void,String> {
    AlertDialog alertDialog;
    Context ctx;

    BackgroundTask(Context ctx) {
        this.ctx = ctx;
    }

    @Override
    protected void onPreExecute() {
    }

    @Override
    protected String doInBackground(String... params) {
        String reg_url = "http://35.160.135.119/webapp/register.php";
        String login_url = "http://35.160.135.119/webapp/login.php";
        String method = params[0];
        if (method.equals("register")) {
            String name = params[1];
            String user_name = params[2];
            String user_pass = params[3];
            try {
                URL url = new URL(reg_url);
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();

                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoOutput(true);
                //httpURLConnection.setDoInput(true);
                OutputStream OS = httpURLConnection.getOutputStream();
                BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(OS, "UTF-8"));
                String data = URLEncoder.encode("user", "UTF-8") + "=" + URLEncoder.encode(name, "UTF-8") + "&" +
                        URLEncoder.encode("user_name", "UTF-8") + "=" + URLEncoder.encode(user_name, "UTF-8") + "&" +
                        URLEncoder.encode("user_pass", "UTF-8") + "=" + URLEncoder.encode(user_pass, "UTF-8");


                bufferedWriter.write(data);
                bufferedWriter.flush();
                bufferedWriter.close();
                OS.close();
                InputStream IS = httpURLConnection.getInputStream();
                IS.close();
                //httpURLConnection.connect();
                httpURLConnection.disconnect();
                return "Registration Success...";
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (method.equals("login")) {
            String login_name = params[1];
            String login_pass = params[2];
            try {
                URL url = new URL(login_url);
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoOutput(true);
                httpURLConnection.setDoInput(true);
                OutputStream outputStream = httpURLConnection.getOutputStream();
                BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
                String data = URLEncoder.encode("login_name", "UTF-8") + "=" + URLEncoder.encode(login_name, "UTF-8") + "&" +
                        URLEncoder.encode("login_pass", "UTF-8") + "=" + URLEncoder.encode(login_pass, "UTF-8");
                bufferedWriter.write(data);
                bufferedWriter.flush();
                bufferedWriter.close();
                outputStream.close();
                InputStream inputStream = httpURLConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
                String response = "";
                String line = "";
                while ((line = bufferedReader.readLine()) != null) {
                    response += line;
                }
                bufferedReader.close();
                inputStream.close();
                httpURLConnection.disconnect();
                return response;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

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

    @Override
    protected void onPostExecute(String result) {
        if (result.equals("Registration Success...")) {
            Toast.makeText(ctx, result, Toast.LENGTH_LONG).show();
        } else {
            alertDialog.setMessage(result);
            alertDialog.show();
        }
    }
}

这是日志

I/System.out: Sending WAIT chunk
W/ActivityThread: Application com.example.jina.a1105gmdemo is waiting for the debugger on port 8100...
I/dalvikvm: Debugger is active
I/System.out: Debugger has connected
I/System.out: waiting for debugger to settle...
Connected to the target VM, address: 'localhost:8600', transport: 'socket'
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: debugger has settled (1372)
I/MultiDex: VM with version 1.6.0 does not have multidex support
I/MultiDex: install
I/MultiDex: MultiDexExtractor.load(/data/app/com.example.jina.a1105gmdemo-35.apk, false)
I/MultiDex: Detected that extraction must be performed.
I/MultiDex: Trying to delete old file /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-34.apk.classes2.dex of size 2898496
I/MultiDex: Deleted old file /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-34.apk.classes2.dex
I/MultiDex: Trying to delete old file /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-34.apk.classes2.zip of size 934986
I/MultiDex: Deleted old file /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-34.apk.classes2.zip
I/MultiDex: Extraction is needed for file /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-35.apk.classes2.zip
I/MultiDex: Extracting /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-35.apk.classes2089171779.zip
I/MultiDex: Renaming to /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-35.apk.classes2.zip
I/MultiDex: Extraction success - length /data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-35.apk.classes2.zip: 934986
I/MultiDex: load found 1 secondary dex files
D/dalvikvm: DexOpt: --- BEGIN 'com.example.jina.a1105gmdemo-35.apk.classes2.zip' (bootstrap=0) ---
D/dalvikvm: DexOpt: --- END 'com.example.jina.a1105gmdemo-35.apk.classes2.zip' (success) ---
D/dalvikvm: DEX prep '/data/data/com.example.jina.a1105gmdemo/code_cache/secondary-dexes/com.example.jina.a1105gmdemo-35.apk.classes2.zip': unzip in 69ms, rewrite 801ms
I/MultiDex: install done
I/FirebaseInitProvider: FirebaseApp initialization unsuccessful

---

在您选择Firebase的Log cat窗口中，您应该选择“仅显示所选应用程序”，然后读取错误，但是，可能您忘记在清单中定义它。

我找不到如何选择该选项。不管怎么说，这个按钮正在工作。我忘记给它下定义了。。现在，当返回到主登录页时，应用程序退出