向下一个Activity传输数据
向下一个Activity传输数据：
Intent intent5 = new Intent(FirstActivity.this,SecondActivity.class);
intent5.putExtra("key_ExtData", "Hello，I'm from FirstActivity！！！");
startActivity(intent5);提取上一个Activity的数据
Intent intent = getIntent();
String data = intent.getStringExtra("key_ExtData");
Log.i("key_ExtData", data);
Toast.makeText(SecondActivity.this, data,Toast.LENGTH_LONG).show();