目录
Activity -> Activity
Activity -> Fragment
Fragment -> Activity
Activity -> Service
Activity -> Activity
实现小例子：
从MainActivity跳转并传值到Activity2，之后从Activity2再传值回到MainActivity
activity_main的布局：
<Buttonandroid:id="@+id/btn_send"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="传值"android:textSize="20sp"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent" /><TextViewandroid:id="@+id/textview_back"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginTop="50dp"android:textSize="20sp"android:text="默认值"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintHorizontal_bias="1.0"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/btn_send"app:layout_constraintVertical_bias="0.0" />
activity2的布局：
<TextViewandroid:id="@+id/text_receive"android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:text="默认值"android:textSize="30dp"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintHorizontal_bias="1.0"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent"app:layout_constraintVertical_bias="0.339" /><EditTextandroid:id="@+id/edit_back"android:layout_width="match_parent"android:layout_height="wrap_content"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintHorizontal_bias="0.0"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/text_receive"app:layout_constraintVertical_bias="0.2" /><Buttonandroid:id="@+id/btn_back"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="返回值"android:textSize="18sp"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/edit_back" />
MainActivity代码（写有备注）:创建Bundle对象，向其里面加入需要传递的值，注意值的类型，添加完毕之后，由intent将该bundle对象传递即可。
注意一下，如果另一个activity2返回来用的是setResult（）函数，那么在MainActivity中传值是需要使用startActivityForResult函数，如果单纯的使用startActivity函数进行跳转，会导致MainActivity中onActivityResult不会执行。
public class MainActivity extends AppCompatActivity implements View.OnClickListener {TextView textView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//获取控件Button button = findViewById(R.id.btn_send);textView = findViewById(R.id.textview_back);button.setOnClickListener(this);}//得到传回的数据@Overrideprotected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {super.onActivityResult(requestCode, resultCode, data);switch (resultCode) {case 1:Bundle bundle_back=data.getExtras();String str=bundle_back.getString("b");textView.setText(str);break;}}//按钮点击事件@Overridepublic void onClick(View view) {switch (view.getId()){case R.id.btn_send:Bundle bundle = new Bundle();bundle.putString("name","玛丽");bundle.putInt("age",15);Intent intent = new Intent(MainActivity.this,Activity2.class);intent.putExtras(bundle);startActivityForResult(intent,0);break;}}}
Activity2代码：在获传递过来值的时候我一直获取为空值，感觉很奇怪，之后发现是有两点导致的
1.被传递到的这个Activity中对Intent的操作，不要写成Intent intent = new Intent();，这样只是会重新在该页面创建了一个新的对象，而需要写成Intent intent = getIntent();去获取前面传递的值。
2.对于获取需要传回的content的放置位置也很关键，不可以放在onCreate()函数里面获取，这样会导致只会在初始化的时候执行一次，之后写入数据后是不会再执行的，会导致传回去的值一直为空。
public class Activity2 extends Activity implements View.OnClickListener {String name,content;int age;EditText editText;@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity2);//获取控件TextView textView = findViewById(R.id.text_receive);editText = findViewById(R.id.edit_back);Button button = findViewById(R.id.btn_back);//接收传来的值并显示Intent intent = getIntent();name = intent.getStringExtra("name");age = intent.getIntExtra("age",-1);textView.setText("名字:"+name+",年龄:"+age);button.setOnClickListener(this);}@Overridepublic void onClick(View view) {switch (view.getId()){case R.id.btn_back://返回值content = editText.getText().toString().trim();Intent intent_back = new Intent(Activity2.this,MainActivity.class);intent_back.putExtra("b",content);setResult(1,intent_back);finish();break;}}}
执行效果如下：
Activity -> Fragment
实现小例子：
从Activity跳转并传值到Fragment
activity_main的布局：
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="/apk/res/android"xmlns:app="/apk/res-auto"xmlns:tools="/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context=".MainActivity"><EditTextandroid:id="@+id/edit_input"android:layout_width="match_parent"android:layout_height="60dp"android:layout_margin="10dp"android:hint="输入内容" /><Buttonandroid:id="@+id/btn_send"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center"android:layout_margin="10dp"android:text="发送"android:textSize="30sp" /><LinearLayoutandroid:id="@+id/contentLayout"android:layout_width="wrap_content"android:layout_height="wrap_content"android:orientation="vertical"></LinearLayout></LinearLayout>
fragment_test的布局：
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="/apk/res/android"xmlns:app="/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent"><TextViewandroid:id="@+id/tvContent"android:layout_width="match_parent"android:layout_height="match_parent"android:text="默认值"android:textSize="25sp"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent" /></androidx.constraintlayout.widget.ConstraintLayout>
MainActivity代码（写有备注）：注意需要将fragment与activity进行绑定。
public class MainActivity extends AppCompatActivity {private EditText edit_input;private Button btn_send;private String inputContent;private FragmentManager manager;private FragmentTransaction transaction;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//获取控件edit_input = findViewById(R.id.edit_input);btn_send = findViewById(R.id.btn_send);//fragment与activity进行绑定manager = getSupportFragmentManager();transaction = manager.beginTransaction();transaction.add(R.id.contentLayout, new FragmentTest());mit();//按钮点击事件btn_send.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {inputContent = edit_input.getText().toString().trim();FragmentTest fragmentTest = new FragmentTest();Bundle bundle = new Bundle();bundle.putString("content", inputContent);fragmentTest.setArguments(bundle);manager = getSupportFragmentManager();transaction = manager.beginTransaction();transaction.replace(R.id.contentLayout, fragmentTest);mit();}});}}
在从Activity -> Fragment传值中，困扰了我很久，我使用FragmentManager manager = getFragmentManager(); 再使用（transaction为FragmentTransaction的对象）
transaction.add(R.id.contentLayout, new FragmentTest());
该句下方会出现红线。最后成功解决使用的方法是FragmentManager manager =getSupportFragmentManager(); 上方导入的为
import androidx.fragment.app.FragmentManager;import androidx.fragment.app.FragmentTransaction;
具体的原因目前我还是不太了解。
FragmentTest代码:
public class FragmentTest extends Fragment {private TextView tvContent;@Nullable@Overridepublic View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {View view = inflater.inflate(R.layout.fragment_test, null);tvContent = view.findViewById(R.id.tvContent);//获取activity传送过来的值Bundle bundle = getArguments();if (bundle != null) {tvContent.setText(bundle.getString("content"));}return view;}}
运行结果如图：
Fragment -> Activity
activity_main的布局：
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="/apk/res/android"xmlns:app="/apk/res-auto"xmlns:tools="/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:id="@+id/contents"tools:context=".MainActivity"><TextViewandroid:id="@+id/tv1"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="默认值"android:textSize="25sp"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent"app:layout_constraintTop_toTopOf="parent" /></androidx.constraintlayout.widget.ConstraintLayout>
fragment_test的布局：
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="/apk/res/android"xmlns:app="/apk/res-auto"xmlns:tools="/tools"android:layout_width="match_parent"android:layout_height="match_parent"><Buttonandroid:id="@+id/btn_send"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="发送"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent" /><EditTextandroid:id="@+id/edit_test"android:layout_width="match_parent"android:layout_height="50dp"android:layout_marginTop="88dp"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/btn_send" /></androidx.constraintlayout.widget.ConstraintLayout>
MainActivity代码（写有备注）:
public class MainActivity extends Activity implements FragmentTest.CallBackValue {private TextView tv1;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);tv1 = (TextView) findViewById(R.id.tv1);//activity与fragment进行绑定FragmentManager manager = getFragmentManager();FragmentTransaction transaction = manager.beginTransaction();transaction.add(R.id.contents, new Fragmen1());mit();}//传递值@Overridepublic void SendMessageValue(String content) {tv1.setText(content);}}
FragmentTest代码:
public class FragmentTest extends Fragment{private Button btn1;private EditText et1;CallBackValue callBackValue;//fragment与activity产生关联是回调这个方法@Overridepublic void onAttach(Activity activity) {super.onAttach(activity);callBackValue =(CallBackValue) getActivity();}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View view = inflater.inflate(R.layout.fragment_layout1, container, false);//获取控件btn1 = (Button) view.findViewById(R.id.btn_send);et1 = (EditText) view.findViewById(R.id.edit_test);//点击事件btn1.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {String content = et1.getText().toString().trim();callBackValue.SendMessageValue(content);}});return view;}//定义一个回调接口public interface CallBackValue{public void SendMessageValue(String content);}}
运行结果截图：
Activity -> Service
activity_main的布局如上。
方法一：使Activity实现implements ServiceConnection ，实现onServiceConnected函数。创ServiceTest.Binder的对象，通过这个对象来实现通信传值。
MainActivity代码（写有备注）:
public class MainActivity extends AppCompatActivity implements ServiceConnection {private EditText edit_input;private Button btn_send;private String inputContent;public ServiceTest.Binder binder = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//获取控件edit_input = findViewById(R.id.edit_input);btn_send = findViewById(R.id.btn_send);//绑定服务Intent intent = new Intent(MainActivity.this,ServiceTest.class);bindService(intent,this, Context.BIND_AUTO_CREATE);//按钮点击事件btn_send.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {inputContent = edit_input.getText().toString().trim();//通过 binder 对象来和 Service 进行通信if(binder != null)binder.sendData(inputContent);}});}@Overridepublic void onServiceConnected(ComponentName componentName, IBinder iBinder) {binder = (ServiceTest.Binder)iBinder;}@Overridepublic void onServiceDisconnected(ComponentName componentName) {}@Overrideprotected void onDestroy() {super.onDestroy();unbindService(this);}}
ServiceTest代码（写有备注）:
public class ServiceTest extends Service {String data;public ServiceTest(){}@Nullable@Overridepublic IBinder onBind(Intent intent) {return new Binder();}public class Binder extends android.os.Binder{public void sendData(String data){ServiceTest.this.data = data;Toast.makeText(ServiceTest.this, "哈哈哈"+data, Toast.LENGTH_SHORT).show();}}}
运行如下：
方法二：使用Intent,适用于传送少量的数据。
MainActivity代码（写有备注）:
public class MainActivity extends AppCompatActivity {private EditText edit_input;private Button btn_send;private String inputContent;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//获取控件edit_input = findViewById(R.id.edit_input);btn_send = findViewById(R.id.btn_send);//绑定服务Intent intent = new Intent(MainActivity.this,ServiceTest.class);//按钮点击事件btn_send.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {inputContent = edit_input.getText().toString().trim();intent.putExtra("test",inputContent);startService(intent);}});}}
ServiceTest代码（写有备注）:
public class ServiceTest extends Service {String data;public ServiceTest(){}@Nullable@Overridepublic IBinder onBind(Intent intent) {return null;}@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {//得到Activity传的数据data = intent.getStringExtra("test");Toast.makeText(ServiceTest.this, "传过来的数据"+data, Toast.LENGTH_SHORT).show();return super.onStartCommand(intent, flags, startId);}}
运行截图：
Android中Activity各种页面跳转并传值（Activity -＞ Activity）（Activity -＞ Fragment）（Activity -＞ Service)
