startActivityForResult获取不到返回值 – Android

使用startActivityForResult与setResult通常解决的场景是:
A Activity打开B Activity,B执行完业务后返回结果给A。

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// 弹出区域选择框(辅助GPS与网络自动获取,提示用户打开GPS与网络,不强制;打开后自动获取,供用户选择)
Intent i = new Intent(MainActivity.this, ProvinceActivity.class);
i.putExtra("currentPosition", "");
startActivityForResult(i, 0);
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/**
* 重写onActivityResult,
*/
@Override
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:// 取出字符串
Bundle bundle = data.getExtras();
String[] result = bundle.getStringArray("currentPosition");

Log.i("position", result.toString());
break;
}

super.onActivityResult(requestCode, resultCode, data);
}


Intent i = new Intent(ProvinceActivity.this, MainActivity.class);
Bundle b = new Bundle();
b.putStringArray("currentPosition", new String[] { mCurrentProviceName, mCurrentCityName, mCurrentDistrictName, mCurrentZipCode });
i.putExtras(b);
this.setResult(RESULT_OK, i);
this.finish();

​ 结果发现无论如何也不能输出结果,查找网络后发现Activity在Manifest注册时lauchMode不能使用singleInstance模式;将A与B的singleInstance去掉之后,正常获取值。