在我的活动中，我正在调用主要活动中的第二个活动startActivityForResult。在我的第二个活动中，有一些方法可以完成此活动（可能没有结果），但是，其中只有一个返回结果。
例如，从主要活动中，我调用了第二个活动。在这个活动中，我正在检查手机的一些功能，例如它是否有摄像头。如果没有，那么我将关闭此活动。此外，在准备期间MediaRecorder或MediaPlayer如果发生问题，我将关闭此活动。
如果它的设备有摄像头并且录制完成，那么在录制视频后，如果用户点击完成按钮，我会将结果（录制视频的地址）发送回主活动。
如何检查主要活动的结果？
从您的FirstActivity, 调用SecondActivityusingstartActivityForResult()方法。
例如：
int LAUNCH_SECOND_ACTIVITY = 1
Intent i = new Intent(this, SecondActivity.class);
startActivityForResult(i, LAUNCH_SECOND_ACTIVITY);
在您的SecondActivity中，设置您要返回的数据FirstActivity。如果您不想返回，请不要设置任何内容。
例如：SecondActivity如果你想发回数据：
Intent returnIntent = new Intent();
returnIntent.putExtra("result",result);
setResult(Activity.RESULT_OK,returnIntent);
finish();
如果您不想返回数据：
Intent returnIntent = new Intent();
setResult(Activity.RESULT_CANCELED, returnIntent);
finish();
现在在您的FirstActivity类中，为该onActivityResult()方法编写以下代码。
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == LAUNCH_SECOND_ACTIVITY) {
if(resultCode == Activity.RESULT_OK){
String result=data.getStringExtra("result");
}
if (resultCode == Activity.RESULT_CANCELED) {
// Write your code if there's no result
}
}
} //onActivityResult
要在 Kotlin 中以更好的方式在两个 Activity 之间传递数据，请阅读“ A better way to pass data between Activities ”。
如何检查主要活动的结果？
您需要覆盖Activity.onActivityResult()然后检查其参数：
requestCode标识哪个应用程序返回了这些结果。这是您在调用时定义的startActivityForResult()。resultCode通知您此应用程序是成功、失败还是其他情况data保存此应用程序返回的任何信息。这可能是null。例子
要在上下文中查看整个过程，这是一个补充答案。有关更多解释，请参阅我的完整答案。
MainActivity.java
public class MainActivity extends AppCompatActivity {
// Add a different request code for every activity you are starting from here
private static final int SECOND_ACTIVITY_REQUEST_CODE = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
// "Go to Second Activity" button click
public void onButtonClick(View view) {
// Start the SecondActivity
Intent intent = new Intent(this, SecondActivity.class);
startActivityForResult(intent, SECOND_ACTIVITY_REQUEST_CODE);
}
// This method is called when the second activity finishes
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// check that it is the SecondActivity with an OK result
if (requestCode == SECOND_ACTIVITY_REQUEST_CODE) {
if (resultCode == RESULT_OK) { // Activity.RESULT_OK
// get String data from Intent
String returnString = data.getStringExtra("keyName");
// set text view with string
TextView textView = (TextView) findViewById(R.id.textView);
textView.setText(returnString);
}
}
}
}
SecondActivity.java
public class SecondActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
}
// "Send text back" button click
public void onButtonClick(View view) {
// get the text from the EditText
EditText editText = (EditText) findViewById(R.id.editText);
String stringToPassBack = editText.getText().toString();
// put the String to pass back into an Intent and close this activity
Intent intent = new Intent();
intent.putExtra("keyName", stringToPassBack);
setResult(RESULT_OK, intent);
finish();
}
}
补充Nishant 的答案，返回活动结果的最佳方法是：
Intent returnIntent = getIntent();
returnIntent.putExtra("result",result);
setResult(RESULT_OK,returnIntent);
finish();
我遇到了问题
new Intent();
然后我发现正确的方法是使用
getIntent();
获取当前意图。
对于我们拥有的新方式registerForActivityResult。
在 Java 中：
// You need to create a launcher variable inside onAttach or onCreate or global, i.e, before the activity is displayed
ActivityResultLauncher<Intent> launchSomeActivity = registerForActivityResult(
new ActivityResultContracts.StartActivityForResult(),
new ActivityResultCallback<ActivityResult>() {
@Override
public void onActivityResult(ActivityResult result) {
if (result.getResultCode() == Activity.RESULT_OK) {
Intent data = result.getData();
// your operation....
}
}
});
public void openYourActivity() {
Intent intent = new Intent(this, SomeActivity.class);
launchSomeActivity.launch(intent);
}
在科特林：
var resultLauncher = registerForActivityResult(StartActivityForResult()) { result ->
if (result.resultCode == Activity.RESULT_OK) {
val data: Intent? = result.data
// your operation...
}
}
fun openYourActivity() {
val intent = Intent(this, SomeActivity::class.java)
resultLauncher.launch(intent)
}
对于那些在 onActivityResult 中有错误 requestCode问题的人
如果您是startActivityForResult()从您的 调用Fragment，则 requestCode 由拥有 Fragment 的 Activity 更改。
如果您想在活动中获得正确的 resultCode，请尝试以下操作：
改变：
startActivityForResult(intent, 1);至：
getActivity().startActivityForResult(intent, 1);
ComponentActivity现在提供一个ActivityResultRegistry允许您处理startActivityForResult()+onActivityResult()和requestPermissions()+onRequestPermissionsResult()流的方法，而无需覆盖Activityor中的方法Fragment，通过 提高类型安全性ActivityResultContract，并提供用于测试这些流的钩子。
强烈建议使用 Android 10 Activity 1.2.0-alpha02 和 Fragment 1.3.0-alpha02 中引入的 Activity Result API。
将此添加到您的build.gradle
def activity_version = "1.2.0-beta01"
// Java language implementation
implementation "androidx.activity:activity:$activity_version"
// Kotlin
implementation "androidx.activity:activity-ktx:$activity_version"
这个新的 API 具有以下预建功能
一个使用 takePicture 合约的例子：
private val takePicture = prepareCall(ActivityResultContracts.TakePicture()) { bitmap: Bitmap? ->
// Do something with the Bitmap, if present
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button.setOnClickListener { takePicture() }
}
那么这里发生了什么？让我们稍微分解一下。takePicture只是一个返回可空位图的回调 - 它是否为空取决于该onActivityResult过程是否成功。prepareCall然后将此调用注册到ComponentActivity名为 the的新功能中ActivityResultRegistry- 我们稍后再讨论。ActivityResultContracts.TakePicture()是 Google 为我们创建的内置助手之一，最后调用takePicture实际上会触发 Intent，就像您之前使用Activity.startActivityForResult(intent, REQUEST_CODE).
一个简单的契约，它将 Int 作为输入并返回一个字符串，请求的 Activity 在结果 Intent 中返回该字符串。
class MyContract : ActivityResultContract<Int, String>() {
companion object {
const val ACTION = "com.myapp.action.MY_ACTION"
const val INPUT_INT = "input_int"
const val OUTPUT_STRING = "output_string"
}
override fun createIntent(input: Int): Intent {
return Intent(ACTION)
.apply { putExtra(INPUT_INT, input) }
}
override fun parseResult(resultCode: Int, intent: Intent?): String? {
return when (resultCode) {
Activity.RESULT_OK -> intent?.getStringExtra(OUTPUT_STRING)
else -> null
}
}
}
class MyActivity : AppCompatActivity() {
private val myActionCall = prepareCall(MyContract()) { result ->
Log.i("MyActivity", "Obtained result: $result")
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
...
button.setOnClickListener {
myActionCall(500)
}
}
}
查看此官方文档以获取更多信息。
If you want to update the user interface with the activity result, you can't to use this.runOnUiThread(new Runnable() {}. Doing this, the UI won't refresh with the new value. Instead, you can do this:
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_CANCELED) {
return;
}
global_lat = data.getDoubleExtra("LATITUDE", 0);
global_lng = data.getDoubleExtra("LONGITUDE", 0);
new_latlng = true;
}
@Override
protected void onResume() {
super.onResume();
if(new_latlng)
{
PhysicalTagProperties.this.setLocation(global_lat, global_lng);
new_latlng=false;
}
}
This seems silly, but it works pretty well.
我将在简短的回答中发布 Android X的新“方式” （因为在某些情况下您不需要自定义注册表或合同）。如果您想了解更多信息，请参阅： 从活动中获取结果
重要提示：Android X 的向后兼容性实际上存在一个错误，因此您必须fragment_version在 Gradle 文件中添加。否则你会得到一个异常 "New result API error : Can only use lower 16 bits for requestCode"。
dependencies {
def activity_version = "1.2.0-beta01"
// Java language implementation
implementation "androidx.activity:activity:$activity_version"
// Kotlin
implementation "androidx.activity:activity-ktx:$activity_version"
def fragment_version = "1.3.0-beta02"
// Java language implementation
implementation "androidx.fragment:fragment:$fragment_version"
// Kotlin
implementation "androidx.fragment:fragment-ktx:$fragment_version"
// Testing Fragments in Isolation
debugImplementation "androidx.fragment:fragment-testing:$fragment_version"
}
现在你只需要添加你的活动的这个成员变量。这使用预定义的注册表和通用合同。
public class MyActivity extends AppCompatActivity{
...
/**
* Activity callback API.
*/
// https://developer.android.com/training/basics/intents/result
private ActivityResultLauncher<Intent> mStartForResult = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(),
new ActivityResultCallback<ActivityResult>() {
@Override
public void onActivityResult(ActivityResult result) {
switch (result.getResultCode()) {
case Activity.RESULT_OK:
Intent intent = result.getData();
// Handle the Intent
Toast.makeText(MyActivity.this, "Activity returned ok", Toast.LENGTH_SHORT).show();
break;
case Activity.RESULT_CANCELED:
Toast.makeText(MyActivity.this, "Activity canceled", Toast.LENGTH_SHORT).show();
break;
}
}
});
在新 API 之前，您有：
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MyActivity .this, EditActivity.class);
startActivityForResult(intent, Constants.INTENT_EDIT_REQUEST_CODE);
}
});
您可能会注意到请求代码现在由 Google 框架生成（并保留）。 您的代码变为：
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MyActivity .this, EditActivity.class);
mStartForResult.launch(intent);
}
});
首先，您startActivityForResult()在第一个中使用 with 参数，Activity如果您想将数据从第二个发送Activity到第一个，然后使用with方法Activity传递值并在第一个方法中获取该数据。IntentsetResult()onActivityResult()Activity
这是Android上非常常见的问题
它可以分为三部分
- 开始活动 B
Intent i = new Intent(A.this, B.class);
startActivity(i);
- 设置请求的数据
在这一部分中，您决定在特定事件发生时是否要发回数据。
例如：在活动 B 中有一个 EditText 和两个按钮 b1、b2。单击按钮 b1 会将数据发送回活动 A。单击按钮 b2 不会发送任何数据。
发送数据
b1......clickListener
{
Intent resultIntent = new Intent();
resultIntent.putExtra("Your_key", "Your_value");
setResult(RES_CODE_A, resultIntent);
finish();
}
不发送数据
b2......clickListener
{
setResult(RES_CODE_B, new Intent());
finish();
}
用户单击后退按钮
默认情况下，使用 Activity.RESULT_CANCEL 响应代码设置结果
- 检索结果
对于那个覆盖 onActivityResult 方法
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RES_CODE_A) {
// b1 was clicked
String x = data.getStringExtra("RES_CODE_A");
}
else if(resultCode == RES_CODE_B){
// b2 was clicked
}
else{
// The back button was clicked
}
}
您需要覆盖 Activity.onActivityResult()：
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_CODE_ONE) {
String a = data.getStringExtra("RESULT_CODE_ONE");
}
else if(resultCode == RESULT_CODE_TWO){
// b was clicked
}
else{
}
}
在科特林
假设 A 和 B 是导航来自 A -> B 的活动 我们需要从 A <- B 返回的结果
在一个
// calling the Activity B
resultLauncher.launch(Intent(requireContext(), B::class.java))
// we get data in here from B
private var resultLauncher =
registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
when (result.resultCode) {
Activity.RESULT_OK -> {
result.data?.getStringExtra("VALUE")?.let {
// data received here
}
}
Activity.RESULT_CANCELED -> {
// cancel or failure
}
}
}
在乙
// Sending result value back to A
if (success) {
setResult(RESULT_OK, Intent().putExtra("VALUE", value))
} else {
setResult(RESULT_CANCELED)
}
在您的主要活动中
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViewById(R.id.takeCam).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent=new Intent(getApplicationContext(),TakePhotoActivity.class);
intent.putExtra("Mode","Take");
startActivity(intent);
}
});
findViewById(R.id.selectGal).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent=new Intent(getApplicationContext(),TakePhotoActivity.class);
intent.putExtra("Mode","Gallery");
startActivity(intent);
}
});
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
}
在要显示的第二个活动中
private static final int CAMERA_REQUEST = 1888;
private ImageView imageView;
private static final int MY_CAMERA_PERMISSION_CODE = 100;
private static final int PICK_PHOTO_FOR_AVATAR = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_take_photo);
imageView=findViewById(R.id.imageView);
if(getIntent().getStringExtra("Mode").equals("Gallery"))
{
pickImage();
}
else {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
requestPermissions(new String[]{Manifest.permission.CAMERA}, MY_CAMERA_PERMISSION_CODE);
} else {
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQUEST);
}
}
}
}
public void pickImage() {
Intent intent = new Intent(Intent.ACTION_PICK);
intent.setType("image/*");
startActivityForResult(intent, PICK_PHOTO_FOR_AVATAR);
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults)
{
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == MY_CAMERA_PERMISSION_CODE)
{
if (grantResults[0] == PackageManager.PERMISSION_GRANTED)
{
Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQUEST);
}
else
{
Toast.makeText(this, "Camera Permission Denied..", Toast.LENGTH_LONG).show();
}
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQUEST && resultCode == Activity.RESULT_OK) {
Bitmap photo = (Bitmap) data.getExtras().get("data");
imageView.setImageBitmap(photo);
}
if (requestCode == PICK_PHOTO_FOR_AVATAR && resultCode == Activity.RESULT_OK) {
if (data == null) {
Log.d("ABC","No Such Image Selected");
return;
}
try {
Uri selectedData=data.getData();
Log.d("ABC","Image Pick-Up");
imageView.setImageURI(selectedData);
InputStream inputStream = getApplicationContext().getContentResolver().openInputStream(selectedData);
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
Bitmap bmp=MediaStore.Images.Media.getBitmap(getContentResolver(),selectedData);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch(IOException e){
}
}
}