先给大家展示下效果展示图：

1 简介

如果想在Activity中得到新打开Activity 关闭后返回的数据，需要使用系统提供的startActivityForResult(Intent intent, int requestCode)方法打开新的Activity，新的Activity 关闭后会向前面的Activity传回数据，为了得到传回的数据，必须在前面的Activity中重写onActivityResult(int requestCode, int resultCode, Intent data)方法。

public class MainActivity extends Activity {private final static String TAG="MainActivity";@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);Button btnOpen=(Button)this.findViewById(R.id.btnOpen);btnOpen.setOnClickListener(new View.OnClickListener(){public void onClick(View v) {//得到新打开Activity关闭后返回的数据//第二个参数为请求码，可以根据业务需求自己编号startActivityForResult(new Intent(MainActivity.this, OtherActivity.class), 1);}});}/*** 为了得到传回的数据，必须在前面的Activity中（指MainActivity类）重写onActivityResult方法** requestCode 请求码，即调用startActivityForResult()传递过去的值* resultCode 结果码，结果码用于标识返回数据来自哪个新Activity*/@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {String result = data.getExtras().getString("result");//得到新Activity 关闭后返回的数据Log.i(TAG, result);}}

当新Activity关闭后，新Activity返回的数据通过Intent进行传递，android平台会调用前面Activity 的onActivityResult()方法，把存放了返回数据的Intent作为第三个输入参数传入，在onActivityResult()方法中使用第三个输入参数可以取出新Activity返回的数据。

2 setResult

使用startActivityForResult(Intent intent, int requestCode)方法打开新的Activity，新Activity关闭前需要向前面的Activity返回数据需要使用系统提供的setResult(int resultCode, Intent data)方法实现：

public class OtherActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.other);Button btnClose=(Button)findViewById(R.id.btnClose);btnClose.setOnClickListener(new View.OnClickListener(){public void onClick(View v) {//数据是使用Intent返回Intent intent = new Intent();//把返回数据存入Intentintent.putExtra("result", "My name is linjiqin");//设置返回数据OtherActivity.this.setResult(RESULT_OK, intent);//关闭ActivityOtherActivity.this.finish();}});}}

setResult()方法的第一个参数值可以根据业务需要自己定义，上面代码中使用到的RESULT_OK是系统Activity类定义的一个常量，值为-1，代码片断如下：

public class android.app.Activity extends ......{public static final int RESULT_CANCELED = 0;public static final int RESULT_OK = -1;public static final int RESULT_FIRST_USER = 1;}

说明：当点击“打开新的Activity”按钮，会跳转到“我是新打开的Activity”页面；

当点击“关闭”按钮，关闭当前页面，同时跳转到“我是旧的Activity”页面，且会传递result参数给前一个Activity

3请求码的作用

使用startActivityForResult(Intent intent, int requestCode)方法打开新的Activity，我们需要为startActivityForResult()方法传入一个请求码(第二个参数)。请求码的值是根据业务需要由自已设定，用于标识请求来源。例如：一个Activity有两个按钮，点击这两个按钮都会打开同一个Activity，不管是那个按钮打开新Activity，当这个新Activity关闭后，系统都会调用前面Activity的onActivityResult(int requestCode, int resultCode, Intent data)方法。在onActivityResult()方法如果需要知道新Activity是由那个按钮打开的，并且要做出相应的业务处理，这时可以这样做：

@Override public void onCreate(Bundle savedInstanceState) {....button1.setOnClickListener(new View.OnClickListener(){public void onClick(View v) {startActivityForResult (new Intent(MainActivity.this, NewActivity.class), 1);}});button2.setOnClickListener(new View.OnClickListener(){public void onClick(View v) {startActivityForResult (new Intent(MainActivity.this, NewActivity.class), 2);}});@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {switch(requestCode){case 1://来自按钮1的请求，作相应业务处理case 2://来自按钮2的请求，作相应业务处理}}}

4 结果码的作用

在一个Activity中，可能会使用startActivityForResult()方法打开多个不同的Activity处理不同的业务，当这些新Activity关闭后，系统都会调用前面Activity的onActivityResult(int requestCode, int resultCode, Intent data)方法。为了知道返回的数据来自于哪个新Activity，在onActivityResult()方法中可以这样做(ResultActivity和NewActivity为要打开的新Activity)：

public class ResultActivity extends Activity {.....ResultActivity.this.setResult(1, intent);ResultActivity.this.finish();}public class NewActivity extends Activity {......NewActivity.this.setResult(2, intent);NewActivity.this.finish();}public class MainActivity extends Activity { // 在该Activity会打开ResultActivity和NewActivity@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {switch(resultCode){case 1:// ResultActivity的返回数据case 2:// NewActivity的返回数据}}}

5 Demo源码：

TestResultActivity.java

package mm.shandong.com.testresult;import android.content.Intent;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.EditText;import android.widget.RadioButton;import android.widget.RadioGroup;import android.widget.TextView;public class TestResultActivity extends AppCompatActivity {EditText editTextBrand;RadioGroup radioGroup;TextView textViewXH;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_test_result);editTextBrand = (EditText) findViewById(R.id.editTextBrand);radioGroup = (RadioGroup) findViewById(R.id.radioGroup);textViewXH = (TextView) findViewById(R.id.textViewXH);RadioButton radionButton = (RadioButton) radioGroup.getChildAt(0);radionButton.setChecked(true);}///跳转到选择品牌界面public void selectBrand(View view) {Intent intent = new Intent(this, TestResultActivity1.class);startActivityForResult(intent, 1);}///选择要购买的电脑public void selectCompute(View view) {Intent intent = new Intent(this, TestResultActivity2.class);String brand = editTextBrand.getText().toString();RadioButton radionButton =(RadioButton) radioGroup.findViewById(radioGroup.getCheckedRadioButtonId());String nc = radionButton.getText().toString();intent.putExtra("brand", brand);intent.putExtra("nc", nc);startActivityForResult(intent, 2);textViewXH.setText("");}///activity请求返回的回调@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent intent) {switch (requestCode) { //resultCode为回传的标记case 1:if (resultCode == 2) {String brand = intent.getStringExtra("brand");editTextBrand.setText(brand);}break;case 2:if (resultCode == 3) {String xh = intent.getStringExtra("xh");textViewXH.setText(xh);}break;}}}

TestResultActivity1

package mm.shandong.com.testresult;import android.content.Intent;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.ArrayAdapter;import android.widget.ListView;import android.widget.Toast;public class TestResultActivity1 extends AppCompatActivity {ListView listView;String[] brands = new String[]{"联想", "戴尔"};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_test_result1);listView = (ListView) findViewById(R.id.listView);ArrayAdapter arrayAdapter = new ArrayAdapter(this,android.R.layout.simple_list_item_checked, brands);listView.setAdapter(arrayAdapter);listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);}///提交选择的品牌结果public void submit(View view) {int index = listView.getCheckedItemPosition();if (index < 0) {Toast.makeText(this, "请选择品牌", Toast.LENGTH_SHORT).show();return;}String brand = (String) listView.getItemAtPosition(index);int resultCode = 2;Intent intent = getIntent();intent.putExtra("brand", brand);setResult(2, intent);finish();}}

TestResultActivity2

package mm.shandong.com.testresult;import android.content.Intent;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.ArrayAdapter;import android.widget.ListView;import android.widget.Toast;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class TestResultActivity2 extends AppCompatActivity {ListView listView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_test_result2);Intent intent=getIntent();String brand=intent.getStringExtra("brand");String nc=intent.getStringExtra("nc");Map map=initData();List<String> lists= (List<String>) map.get(brand+nc);listView= (ListView) findViewById(R.id.listView);ArrayAdapter arrayAdapter=new ArrayAdapter(this,android.R.layout.simple_list_item_checked,lists);listView.setAdapter(arrayAdapter);listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);}///提交选择的电脑型号public void submit(View view){int index= listView.getCheckedItemPosition();if(index<0){Toast.makeText(this,"请选择型号",Toast.LENGTH_SHORT).show();return ;}String xh= (String) listView.getItemAtPosition(index);int resultCode=2;Intent intent=getIntent();intent.putExtra("xh",xh);setResult(3,intent);finish();}///初始化数据源public Map initData(){Map map=new HashMap();List<String> lists=new ArrayList<>();lists.add("联想1G0001");lists.add("联想1G0002");map.put("联想1G",lists);lists=new ArrayList<>();lists.add("联想2G0001");lists.add("联想2G0002");map.put("联想2G",lists);lists=new ArrayList<>();lists.add("戴尔1G0001");lists.add("戴尔1G0002");map.put("戴尔1G",lists);lists=new ArrayList<>();lists.add("戴尔2G0001");lists.add("戴尔2G0002");map.put("戴尔2G",lists);return map;}}

以上所述是小编给大家介绍的Activity实例详解之启动activity并返回结果，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对网站的支持！