private String PREFS_KEY = "misdatos";

public void guardaIP(Context context, String valor) {
    SharedPreferences settings = context.getSharedPreferences(PREFS_KEY, MODE_PRIVATE);
    SharedPreferences.Editor editor;
    editor = settings.edit();
    editor.putString("myIP", valor);
    editor.commit();
}



public String obtieneIP(Context context) {
    SharedPreferences preferences = context.getSharedPreferences(PREFS_KEY, MODE_PRIVATE);
    return  preferences.getString("myIP", "");
}

guardaIP(getApplicationContext(), EditTextIP.getText().ToString());

EditTextIP.setText(obtieneIP(getApplicationContext()));