MainActivity.java package com.example.aris.hellotoast; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.TextView; import android.widget.Toast; public class MainActivity extends AppCompatActivity { private TextView mShowCount; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void showToast(View view) { mShowCount = (TextView) findViewById(R.id.show_count); Toast.makeText(MainActivity.this, "Toast Success", Toast.LENGTH_SHORT).show(); } public void countUp(View view) { int mCount = Integer.valueOf(String.valueOf(mShowCount.getText())); mCount++; if (mShowCount != null) mShowCount.setText(Integer.toString(mCount)); } }