startActivityForResult和setResult案例详解

Intent intent=new Intent();
intent.setClass(A.this, B.class);
Bundle bundle=new Bundle();
String str1="aaaaaa";
bundle.putString("str1", str1);
intent.putExtras(bundle);
startActivityForResult(intent, 0);//这里采用startActivityForResult来做跳转，此处的0为一个依据，可以写其他的值，但一定要>=0

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (resultCode) { //resultCode为回传的标记，我在B中回传的是RESULT_OK
   case RESULT_OK:
    Bundle b=data.getExtras(); //data为B中回传的Intent
    String str=b.getString("str1");//str即为回传的值
    break;
default:
    break;
    }
}

setResult(RESULT_OK, intent); //intent为A传来的带有Bundle的intent，当然也可以自己定义新的Bundle
finish();//此处一定要调用finish()方法

public final void setResult(int resultCode, Intent data) {
        synchronized (this) {
            mResultCode = resultCode;
            mResultData = data;
        }
    }

    public void finish() {
        if (mParent == null) {
            int resultCode;
            Intent resultData;
            synchronized (this) {
                resultCode = mResultCode;
                resultData = mResultData;
            }
            if (Config.LOGV) Log.v(TAG, "Finishing self: token=" + mToken);
            try {
                if (ActivityManagerNative.getDefault()
                    .finishActivity(mToken, resultCode, resultData)) {
                    mFinished = true;
                }
            } catch (RemoteException e) {
                // Empty
            }
        } else {
            mParent.finishFromChild(this);
        }
    }

@Override
    public void onBackPressed() {
        Log.i(TAG, "onBackPressed");
        setResult(Const.LIVE_OK);
        super.onBackPressed();
    }