Android Studio Login Form

Question

Ich versuche, ein Login-Formular zu machen:

TextView tv = (TextView) findViewById(R.id.btnRegister); 
    tv.setClickable(true); 
    tv.setMovementMethod(LinkMovementMethod.getInstance()); 
    tv.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      startActivity(new Intent(MainActivity.this, Register.class)); 
     } 
}); 

username=(EditText)findViewById(R.id.Uname); 
password=(EditText)findViewById(R.id.Pword); 
party=username.getText().toString(); 
p2=password.getText().toString(); 
ok=(Button)findViewById(.id.btnLogin); 

ok.setOnClickListener(new View.OnClickListener() { 
    @Override 
    public void onClick(View v) { 
     if(party.isEmpty() && p2.isEmpty()){ 
      Toast.makeText(MainActivity.this, "empty fields", Toast.LENGTH_SHORT).show(); 
      return; 
     } else if(!party.isEmpty() && !p2.isEmpty()){ 
      db.execSQL("select * from Students where Name='"+party+"'and Password='"+p2+"'"); 
      Toast.makeText(MainActivity.this, "Welcome", Toast.LENGTH_SHORT).show(); 
      startActivity(new Intent(MainActivity.this,Welcome.class)); 
     } 
    } 
}); 

Wenn ich den Benutzernamen und das Passwort den Toast eingeben i machen "leeren Felder" zu zeigen, wenn ich es, klicken Sie bitte sagt leere Felder:

Answer 1

versuchen mit Länge

if(party.toString().trim().length < 0 && p2.toString().trim().length < 0){ 

Toast.makeText(MainActivity.this, "empty fields", Toast.LENGTH_SHORT).show(); 

return; 

}else { 

db.execSQL("select * from Students where Name='"+party+"'and Password='"+p2+"'"); 

Toast.makeText(MainActivity.this, "Welcome", Toast.LENGTH_SHORT).show(); 

startActivity(new Intent(MainActivity.this,Welcome.class)); 

} 

Answer 2

username = (EditText) findViewById(R.id.Uname); 
password = (EditText) findViewById(R.id.Pword); 

party = username.getText().toString(); 
p2 = password.getText().toString(); 


ok = (Button) findViewById(R.id.btnLogin); 
ok.setOnClickListener(new View.OnClickListener() { 

    @Override 
    public void onClick(View v) { 
     if (party.equals("") || p2.equals("")) { 

      Toast.makeText(MainActivity.this, "empty fields", Toast.LENGTH_SHORT).show(); 

     } else { 

      db.execSQL("select * from Students where Name='" + party + "'and Password='" + p2 + "'"); 

      Toast.makeText(MainActivity.this, "Welcome", Toast.LENGTH_SHORT).show(); 

      startActivity(new Intent(MainActivity.this, Welcome.class)); 

     } 

    } 

}); 

Answer 3

Bitte versuchen Sie, diese Arbeit für mich.

if (TextUtils.isEmpty(party) || TextUtils.isEmpty(p2)) { 
     Toast.makeText(MainActivity.this, "empty fields", Toast.LENGTH_SHORT).show(); 
    } else 

    { 
     db.execSQL("select * from Students where Name='" + party + "'and Password='" + p2 + "'"); 
     Toast.makeText(MainActivity.this, "Welcome", Toast.LENGTH_SHORT).show(); 
     startActivity(new Intent(MainActivity.this, Welcome.class)); 
    }