as 通信

https://blog.csdn.net/jiayu0855/article/details/78759471

Intent intent=new Intent(MainActivity.this, SecondActivity.class); startActivity(intent);```

https://blog.csdn.net/blueair_ren/article/details/52818778
1,intent

@1通过Intent向下一个活动发送数据。
String data = "nihao";                                                                      Intent intent = new Intent(activity1.this,activity2.class);
intent.putExtra("send_data",data);
startActivity(intent);
@2通过intent接收来自上一个活动的数据。
Intent intent = getIntent();
String data = intent.getStringExtra("send_data");

2.bundle
第一个activity

       Intent intent=new Intent(MainActivity.this, SecondActivity.class);
                Bundle bundle = new Bundle();
                bundle.putString("aa","ddkkddk");
                intent.putExtras(bundle);
                startActivity(intent);

第二个activity

    final Intent intent = getIntent();
        Bundle bundle = intent.getExtras();
        Log.e("leo", "onCreate: " + bundle.getString("aa"));

3.activity 与 fragment通信

    Bundle bundle = new Bundle();
                bundle.putString("message","我喜欢享学课堂");
                BlankFragment1 bf = new BlankFragment1();
                bf.setArguments(bundle);
                replacefragment(bf);

      Bundle bundle=this.getArguments();
        Log.e("leo", "onCreate: "+ bundle.getString("message"));