MainActivity.java

package com.example.librarymanagement;

import android.app.Activity;
import android.graphics.Color;
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 MainActivity extends Activity  {
    Button b1,b2;
    EditText ed1,ed2;

    TextView tx1;
    int counter = 3;

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

        b1 = (Button)findViewById(R.id.button);
        ed1 = (EditText)findViewById(R.id.editText);
        ed2 = (EditText)findViewById(R.id.editText2);

        b2 = (Button)findViewById(R.id.button2);
        tx1 = (TextView)findViewById(R.id.textView3);
        tx1.setVisibility(View.GONE);

        b1.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                if(ed1.getText().toString().equals("admin") &&
                        ed2.getText().toString().equals("admin"))
                {
                    Toast.makeText(getApplicationContext(),
                            "Redirecting...",Toast.LENGTH_SHORT).show();
                }
                else
                    {
                        Toast.makeText(getApplicationContext(), "Wrong Credentials",Toast.LENGTH_SHORT ).show();

                        tx1.setVisibility(View.VISIBLE);
                        tx1.setBackgroundColor(Color.RED);
                    counter--;
                    tx1.setText(Integer.toString(counter));

                    if (counter == 0)
                    {
                        b1.setEnabled(false);
                    }
                    }
            }
        });

        b2.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                finish();
            }
        });
    }
}