運行簡單登錄應用程序的問題

Question

我正在學習從YouTube上製作一個簡單的登錄應用程序，但是，當我構建代碼時，儘管應用程序運行良好，但它從未將值3分配給嘗試計數器代碼，只有佈局是可見的，因此登錄不起作用。你能幫我麼？如果您需要其他文件，請將其寫入評論中，稍後再上傳。謝謝。

package com.shubham.splashscreenemulation; 

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


public class UserLogin extends AppCompatActivity { 

private static EditText username; 
private static EditText password; 
private static TextView attempts_left; 
private static Button login_btn; 
int attempt_counter = 3; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_user_login); 
} 

public void LoginButton(){ 

    username = (EditText)findViewById(R.id.editText_user); 
    password = (EditText)findViewById(R.id.editText_password); 
    attempts_left = (TextView)findViewById(R.id.textView_attempt_count); 
    login_btn = (Button)findViewById(R.id.button_login); 

    attempts_left.setText(Integer.toString(attempt_counter)); 

    login_btn.setOnClickListener(
      new View.OnClickListener(){ 

       @Override 
       public void onClick(View v){ 

        if(username.getText().toString().equals("Shubh") && password.getText().toString().equals("adidev")) 
        { 
         Toast.makeText(UserLogin.this, "Login credentials are correct!", Toast.LENGTH_SHORT).show(); 
         Intent intent = new Intent("com.shubham.splashscreenemulation.SplashScreen"); 
         startActivity(intent); 
        } 

        else 
        { 
         Toast.makeText(UserLogin.this, "Login credentials are not correct!", Toast.LENGTH_SHORT).show(); 
         attempt_counter--; 
         attempts_left.setText(Integer.toString(attempt_counter)); 
         if(attempt_counter == 0) 
         { 
          login_btn.setEnabled(false); 
         } 
        } 
       } 


      } 

    ); 
} 


} 

Answer 1

您不要在Activity中調用函數LoginButton（）。

這裏有一些提示：函數名以小寫字母開頭，如loginButton（帶有camelCase），類名以像AppCompatActivity這樣的大寫字母開頭。這個提示是爲了更好的代碼可讀性。爲什麼你在該函數中聲明Views是靜態的？

package com.shubham.splashscreenemulation; 

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


public class UserLogin extends AppCompatActivity { 

private static EditText username; 
private static EditText password; 
private static TextView attempts_left; 
private static Button login_btn; 
int attempt_counter = 3; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_user_login); 
    LoginButton(); 

} 

public void LoginButton(){ 

    username = (EditText)findViewById(R.id.editText_user); 
    password = (EditText)findViewById(R.id.editText_password); 
    attempts_left = (TextView)findViewById(R.id.textView_attempt_count); 
    login_btn = (Button)findViewById(R.id.button_login); 

    attempts_left.setText(Integer.toString(attempt_counter)); 

    login_btn.setOnClickListener(
      new View.OnClickListener(){ 

       @Override 
       public void onClick(View v){ 

        if(username.getText().toString().equals("Shubh") && password.getText().toString().equals("adidev")) 
        { 
         Toast.makeText(UserLogin.this, "Login credentials are correct!", Toast.LENGTH_SHORT).show(); 
         Intent intent = new Intent("com.shubham.splashscreenemulation.SplashScreen"); 
         startActivity(intent); 
        } 

        else 
        { 
         Toast.makeText(UserLogin.this, "Login credentials are not correct!", Toast.LENGTH_SHORT).show(); 
         attempt_counter--; 
         attempts_left.setText(Integer.toString(attempt_counter)); 
         if(attempt_counter == 0) 
         { 
          login_btn.setEnabled(false); 
         } 
        } 
       } 


      } 

    ); 
} 

Answer 2

您可以setContentView之後添加LoginButton()或刪除LoginButton方法，將裏面的onCreate一切。

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_user_login); 
     username = (EditText)findViewById(R.id.editText_user); 
     password = (EditText)findViewById(R.id.editText_password); 
     attempts_left = (TextView)findViewById(R.id.textView_attempt_count); 
     login_btn = (Button)findViewById(R.id.button_login); 
     attempts_left.setText(Integer.toString(attempt_counter)); 
     login_btn.setOnClickListener(new View.OnClickListener(){ 

      @Override 
       public void onClick(View v){ 
       if(username.getText().toString().equals("Shubh") && password.getText().toString().equals("adidev")) 
        { 
        Toast.makeText(UserLogin.this, "Login credentials are correct!", Toast.LENGTH_SHORT).show(); 
        Intent intent = new Intent("com.shubham.splashscreenemulation.SplashScreen"); 
        startActivity(intent); 
        } 
        else 
        { 
         Toast.makeText(UserLogin.this, "Login credentials are not correct!", Toast.LENGTH_SHORT).show(); 
         attempt_counter--;      attempts_left.setText(Integer.toString(attempt_counter)); 
         if(attempt_counter == 0) 
         { 
          login_btn.setEnabled(false); 
         } 
        } 
       } 
       }); 
      } 

你也可以改變你的setText這個attempts_left.setText(attempt_counter+"");