带有返回值的intent

1.启动activity　

　　

Intent intent = new Intent(MainActivity.this,Other.class);
intent.putExtra("message", a+" + "+b+" = ");
startActivityForResult(intent, 1000);

2.重写onActivityResult 比较请求码和返回码

 if(requestCode==1000 && resultCode==1001){}

3.返回结果

Intent intent = new Intent();
intent.putExtra("result", value);
setResult(1001, intent);
finish();