Intent传输数据-3

1.显式intent

Intent intent = new Intent(this,second.class);
intent.putExtra("data");
startActivity(intent);


Intent intent = getIntent();
String data = intent.getStringExtra("data");


推荐写法：
second：
public static void actionStart(Context context, String data1, String data2) ｛
    Intent intent = new Intent(context,second.class);
    intent.putExtra("param1", data1);
    intent.putExtra("param2", data2);
    context.startActivity(intent);
｝

first：
second.actionStart(this,"data1","data2");

2.startAcivityForResult

First:
Intent intent = new Intent(this,second.class);
startAcivityForResult(intent, 1);

 @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case 1:
                if (resultCode == RESULT_OK) {
                    String returnedData = data.getStringExtra("data_return");
                    Log.d("FirstActivity", returnedData);
                }
                break;
            default:
        }
    }

second:
Intent intent = new Intent();
intent.putExtra("data_return","hello first");
setResult(RESULT_OK,intent);
finish();

@Override
public void onBackPressed() {//back键退出特殊情况
        Intent intent = new Intent();
        intent.putExtra("data_return", "hello first");
        setResult(RESULT_OK, intent);
        finish();
    }