Pass data between activity

When start a new activity in our main activity using startActivity(), data can be passed using Bundle.

Inside the main activity, MainActivity.java

            Intent intent = new Intent();
           intent.setClass(MainActivity.this, NewActivity.class);
          
           Bundle bundle = new Bundle();
           bundle.putCharSequence("extraCharSequence", "hello");
           bundle.putInt("extraInt", 12345);
           //...
           intent.putExtras(bundle);
           startActivity(intent);

Get the data in onCreate() of the new activity, NewActivity.java

    public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
      
       Bundle bundle = this.getIntent().getExtras();
       CharSequence dataCharSequence = bundle.getCharSequence("extraCharSequence");
       int dataInt = bundle.getCharSequence("extraInt");
      

    };

The code this.getIntent().getExtras() return the map of all extras previously added with putExtra(), or null if none have been added.