在android中使用全局变量时出错 [英] Error while using global variable in android

问题描述

我正在尝试实现一个登录屏幕，其中在休息服务的帮助下验证用户名和密码。



i创建了一个像这样的全局类

i am trying to implement a login screen where username and password are validated with the help of a rest service.

i have created a global class like this

public class GlobalClass extends Application{
    String url="myRestService";
    String newURL;

    public String getName() {
        return url;
    }

    public void setName(String aName) {
        url = aName;
    }

    public String getNewURL() {
        return newURL;
    }

    public void setNewURL(String bName) {
        newURL = bName;
    }
}

我创建了一个屏幕，其中superadmin可以更改其余服务，如

此课程旨在更新其余服务

I have created a screen where the superadmin can change the rest service like
this class is intented to update the rest service

final GlobalClass globalVariable = new GlobalClass();
        String restMethod=globalVariable.getName();
        et.setText(restMethod);
        b= (Button) findViewById(R.id.button);

        b.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String userEnteredMethod=et.getText().toString();
                globalVariable.setNewURL(userEnteredMethod);
                Toast.makeText(getApplicationContext(),userEnteredMethod,Toast.LENGTH_SHORT).show();
                Intent login=new Intent(getApplicationContext(),Login.class);
                startActivity(login);
            }
        });

现在在我的登录名单中

i称为全球像这样的类并获取URL

Now in my login
i called the global class like this and get the url

final GlobalClass gb = new GlobalClass();
       userEnteredMethod = gb.getNewURL();

String newURL = userEnteredMethod.concat("/MethodResult");
        AsyncHttpClient client = new AsyncHttpClient();
        client.get(newURL, params, new AsyncHttpResponseHandler() {
            @Override
            public void onSuccess(String response) {
                try {
                   // prgDialog.hide();
                    JSONObject obj = new JSONObject(response);
                    if (obj != null) {
                        JSONArray data = obj.getJSONArray("ValidateSubscriberLoginResult");
                        for (int i = 0; i < data.length(); i++) {
                            JSONObject user = data.getJSONObject(i);
                            //
                            if (!user.getString("ID").equals("0")) {
                               Toast.makeText(getApplicationContext(),"success",Toast.LENGTH_SHORT).show();
                            } else
                            {
                                Toast.makeText(getApplicationContext(),"Check again",Toast.LENGTH_SHORT).show();
                            }
                        }
                    }
                } catch (JSONException e) {
                    Toast.makeText(getApplicationContext(), "Error Occured [Server's JSON response might be invalid]!", Toast.LENGTH_LONG).show();

                    e.printStackTrace();
                }
                super.onSuccess(response);
            }

执行代码我在字符串中获得空指针异常newURL = userEnteredMethod.concat（/ MethodResult）;

在调试时我发现我在userEnteredMethod = gb.getNewURL（）时得到一个空值;



请帮我纠正问题

on executing the code i'm getting a null pointer exception in String newURL = userEnteredMethod.concat("/MethodResult");
while debuging i found out that i am getting a null value at userEnteredMethod = gb.getNewURL();

please help me to rectify the problem

推荐答案

当然不行。

Of course it won't work.

final GlobalClass gb = new GlobalClass();<br />
String userEnteredMethod = gb.getNewURL();

您已实例化一个新对象。因此，它会给你 null 。 :)

You have instantiated a new object. Hence, it'll give you null. :)

// obn button click, before the startACtivity()
login.putExtra("URL", globalVariable.getNewURL);


// in login
Bundle extras = getIntent().getExtras();
String url = extras.getString("URL");
String newURL = url.concat("/MethodResult");
AsyncHttpClient client = new AsyncHttpClient();
// your rest of the code

-KR

-KR

这篇关于在android中使用全局变量时出错的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！