Login UI for an Android app

Question

This code starts a new thread for login and reacts according to the JSON result returned by the server.

I think this code has too many conditionals, exception handlers, and nested functions.

public void Login() {
    mButton.setClickable(false);
    mButton.setText("Loading...");
    final String username = mUserName.getText().toString().trim();
    final String password = mPassWord.getText().toString().trim();

    new Thread() {
        public void run() {
            final String result = NetUtil.loginByGet(username, password);
            if (result != null) {
                try {
                    JSONTokener jsonTokener = new JSONTokener(result);
                    JSONObject jsonObject = (JSONObject) jsonTokener.nextValue();
                    final String message = jsonObject.getString("message");
                    if (jsonObject.getInt("error") == 0) {
                        String token = jsonObject.getString("token");
                        boolean isSaveSuccess = InfoUtil.saveUserInfo(LoginActivity.this,token);
                        if (isSaveSuccess) {
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    Toast.makeText(LoginActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
                                    initIntent(MainActivity.class);
                                    finish();
                                }
                            });
                        }else {
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    Toast.makeText(LoginActivity.this, "保存登录信息失败", Toast.LENGTH_SHORT).show();
                                    mButton.setClickable(true);
                                    mButton.setText("登录");
                                }
                            });
                        }
                    } else if(jsonObject.getInt("error") == 1) {
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(LoginActivity.this, "" + message,
                                        Toast.LENGTH_SHORT).show();
                                mButton.setClickable(true);
                                mButton.setText("登录");
                            }
                        });
                    }
                }catch (Exception e) {
                    e.printStackTrace();
                }
            } else {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(LoginActivity.this, "请求失败", Toast.LENGTH_SHORT).show();
                        mButton.setClickable(true);
                        mButton.setText("登录");
                    }
                });
            }
        }
    }.start();
}

Answer 1

Using an AsyncTask instead would be much better. You've got many callbacks to the UI thread, all of this you could do in the post execute method instead:

private class LoginTask extends AsyncTask<Void, Void, String>{

    private String username;
    private String password;
    private Exception exception;
    private boolean isSaveSuccess;

    public LoginTask(String username, String password){
        this.username = username;
        this.password = password;
    }

    @Override
    protected String doInBackground(Void... voids) {
        try{
            String result = NetUtil.loginByGet(username, password);
            //Grab the token
            isSaveSuccess = InfoUtil.saveUserInfo(LoginActivity.this,token);
        }catch(Exception ex){
            //Catch any given exception to use it in the post execution (e.g. show a toast)
            this.exception = ex;
        }
    }

    @Override
    protected void onPostExecute(String result) {
        //Here it goes your UI logic
    }

} 

To call it, just launch an execution when login button is clicked:

public void doLogin(){    
    mButton.setClickable(false);
    mButton.setText("Loading...");
    String username = mUserName.getText().toString().trim();
    String password = mPassWord.getText().toString().trim();
    new LoginTask(username, password).execute();
}