首页 > 代码库 > Android之startActivity、startActivityForResult和setResult详解
Android之startActivity、startActivityForResult和setResult详解
[PS:还是以GOOGLE原生的BluetoothChat为例]
1. startActivity与startActivityForResult的区别
startActivity( ) 仅仅是跳转到目标页面，若是想跳回当前页面，则必须再使用一次startActivity( )。
startActivityForResult( ) 可以一次性完成这项任务，当程序执行到这段代码的时候，假若从T1Activity跳转到下一个Text2Activity，
而当这个Text2Activity调用了finish()方法以后，程序会自动跳转回T1Activity，并调用前一个T1Activity中的onActivityResult( )方法。
例如在BluetoothChat类中，对跳转到DeviceListActivity类采用的是startActivityForResult( ) 方式：
@Override public boolean onOptionsItemSelected(MenuItem item) { Intent serverIntent = null; switch (item.getItemId()) { case R.id.secure_connect_scan: // Launch the DeviceListActivity to see devices and do scan serverIntent = new Intent(this, DeviceListActivity.class); startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE_SECURE); return true; case R.id.insecure_connect_scan: // Launch the DeviceListActivity to see devices and do scan serverIntent = new Intent(this, DeviceListActivity.class); startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE_INSECURE); return true; case R.id.discoverable: // Ensure this device is discoverable by others ensureDiscoverable(); return true; } return false; }
在DeviceActivity中则使用setResult()方法返回值：
// The on-click listener for all devices in the ListViews private OnItemClickListener mDeviceClickListener = new OnItemClickListener() { public void onItemClick(AdapterView<?> av, View v, int arg2, long arg3) { // Cancel discovery because it‘s costly and we‘re about to connect mBtAdapter.cancelDiscovery(); // Get the device MAC address, which is the last 17 chars in the View String info = ((TextView) v).getText().toString(); String address = info.substring(info.length() - 17); // Create the result Intent and include the MAC address Intent intent = new Intent(); intent.putExtra(EXTRA_DEVICE_ADDRESS, address); // Set result and finish this Activity setResult(Activity.RESULT_OK, intent); finish(); } };
但是，要注意，如果在startActivityForResult跳转到的Activity里面设置setResult，结果并不会马上返回给parent的Activity，只有当前Activity被finish，
结果才会被发送给parent的onActivityResult去处理：
public void onActivityResult(int requestCode, int resultCode, Intent data) { if(D) Log.d(TAG, "onActivityResult " + resultCode); switch (requestCode) { case REQUEST_CONNECT_DEVICE_SECURE: // When DeviceListActivity returns with a device to connect if (resultCode == Activity.RESULT_OK) { connectDevice(data, true); } break; case REQUEST_CONNECT_DEVICE_INSECURE: // When DeviceListActivity returns with a device to connect if (resultCode == Activity.RESULT_OK) { connectDevice(data, false); } break; case REQUEST_ENABLE_BT: // When the request to enable Bluetooth returns if (resultCode == Activity.RESULT_OK) { // Bluetooth is now enabled, so set up a chat session setupChat(); } else { // User did not enable Bluetooth or an error occurred Log.d(TAG, "BT not enabled"); Toast.makeText(this, R.string.bt_not_enabled_leaving, Toast.LENGTH_SHORT).show(); finish(); } } }
Android之startActivity、startActivityForResult和setResult详解
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。