startActivity和startActivityForResult用法详解

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startActivity(Intent intent)：仅仅是从当前活动界面跳转到另外一个界面，之后两个界面之间不再有联系。若是想跳回当前页面，则必须再使用一次startActivity( )。

startActivityForResult(Intent intent, int requestCode):可以经当前活动界面认为是一个父窗体，要跳转的界面为子窗体，当子窗体关闭时，父窗体会执行onActivityResult()方法，并可以获取子窗体的返回值.

代码如下：

mainActivity:

其中点击btn_main_start1为启动startActivity(); 点击btn_main_start2为启动startActivityForResult()

public class MainActivity extends Activity implements OnClickListener {private EditText et_main_message;private Button btn_main_start1;private Button btn_main_start2;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// 初始化视图对象et_main_message = (EditText) findViewById(R.id.et_main_message);btn_main_start1 = (Button) findViewById(R.id.btn_main_start1);btn_main_start2 = (Button) findViewById(R.id.btn_main_start2);// 设置点击监听btn_main_start1.setOnClickListener(this);btn_main_start2.setOnClickListener(this);}@Overridepublic void onClick(View v) {if (v == btn_main_start1) {// 1.创建Intent对象(显式)Intent intent = new Intent(this, SecondActivity.class);// 2.通过intent携带额外数据String message = et_main_message.getText().toString();intent.putExtra("MESSAGE", message);// 3.启动ActivitystartActivity(intent);} else if (v == btn_main_start2) {//1.创建Intent对象Intent intent = new Intent(this, SecondActivity.class);// 2.通过intent携带额外数据String message = et_main_message.getText().toString();intent.putExtra("MESSAGE", message);// 3.启动Activityint requestCode = 2;startActivityForResult(intent, requestCode);}}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {// 判断codeif (requestCode == 2 && resultCode == 3) {// 从data中取出数据String result = data.getStringExtra("RESULT");// 显示et_main_message.setText(result);}}}

SecondActivity:

public class SecondActivity extends Activity {private EditText et_second_message;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_second);et_second_message = (EditText) findViewById(R.id.et_second_message);// 得到intent对象Intent intent = getIntent();// 通过intent读取额外数据String message = intent.getStringExtra("MESSAGE");// 显示到EditTextet_second_message.setText(message);}public void back1(View v) {// 关闭当前界面finish();}public void back2(View v) {// 保存一个结果int resultCode = 3;// 准备一个带额外数据的intent对象Intent data = new Intent();String result = et_second_message.getText().toString();data.putExtra("RESULT", result);// 设置结果setResult(resultCode, data);// 关闭当前界面finish();}}

其中点击btn_main_start1为启动startActivity(); 点击btn_main_start2为启动startActivityForResult()

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