Android Studio getApplicationcontext（）

Question

如果用户没有输入用户名和密码，我想弹出消息，但是我的问题是getApplicationcontext（），它说“无法解析方法”。我如何解决它？ - - - - - - - - - - - - - - - - - - - - - - -------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -----------------------------------------------

package com.example.rojean.prelim_project; 

import android.support.v7.app.AppCompatActivity; 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 

public class LoginActivity extends AppCompatActivity { 

    Button loginBtn; 
    EditText txtUsername, txtPassword; 
    AccountsManagement session; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_login); 

     Object getApplication; 
     session = new AccountsManagement(getApplicationcontext()); 

     txtUsername = (EditText) findViewById(R.id.nameField); 
     txtPassword = (EditText) findViewById(R.id.passwordField); 

     Toast.makeText(getApplicationContext(), 
       "User Login Status: " + session.isUserLoggedIn(), 
       Toast.LENGTH_LONG).show(); 

     loginBtn = (Button)findViewById(R.id.loginBtn); 
     loginBtn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

       String username = txtUsername.getText().toString(); 
       String password = txtPassword.getText().toString(); 

       //Validation method 
       if(username.trim().length() > 0 && password.trim().length() > 0){ 
        // For testing puspose username, password is checked with static data 
        // username = admin 
        // password = admin 

        if(username.equals("admin") && password.equals("admin")){ 

         // Creating user login session 
         // Statically storing name="Android Example" 
         // and email="androidexample84@gmail.com" 
         session.createUserLoginSession("Android Example", 
           "androidexample84@gmail.com"); 

         // Starting MainActivity 
         Intent i = new Intent(getApplicationContext(), MainActivity.class); 
         i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 

         // Add new Flag to start new Activity 
         i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 
         startActivity(i); 

         finish(); 
        }else{ 

         // username/password doesn't match& 
         Toast.makeText(getApplicationContext(), 
           "Username/Password is incorrect", 
           Toast.LENGTH_LONG).show(); 
        } 
       }else{ 

        // user didn't entered username or password 
        Toast.makeText(getApplicationContext(), 
          "Please enter username and password", 
          Toast.LENGTH_LONG).show(); 

       } 
      } 
     }); 
    } 

} 

Answer 1

尝试的LoginActivity.this代替getApplicationContext()

Answer 2

使用this而不是getApplicationContext()：

Toast.makeText(this, "User Login Status: " + session.isUserLoggedIn(), Toast.LENGTH_LONG).show; 

通过这种方式，您可以获得活动的上下文。

Answer 3

请勿使用getApplicationContext()。获取活动上下文的最佳方式是使用LoginActivity.this，其中this是指上下文本身。