Android(安卓)之startActivityForReult 与 onActivityResult简介

startActivityForResult与startActivity的不同之处在于：
1、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( )。
2、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。

相关函数:
startActivityForResult(Intent intent, Int requestCode)
setResut(int resultCode, Intent intent)
onActivityResult(int requestCode, int resultCode, Intent intent)

-----------MainActivity----------------------------------------------

public class MainActivity extends Activity {

TextView t;
public static final int REQUSET = 110; //一定要>=0

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

t = (TextView)findViewById(R.id.toOther);

Button b = (Button)findViewById(R.id.toOther_btn);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent in = new Intent();
in.setClass(getApplicationContext(), OtherActivity.class);
startActivityForResult(in, REQUSET);
}
});
}

/**--requestCode:请求码 resultCode:结果码，用于标识返回数据来自哪个新Activity */
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);

if(requestCode == REQUSET && resultCode == OtherActivity.RESULT_OK){
String str = "帐号："+data.getStringExtra(OtherActivity.KEY_USER_ID)+"\n密码:"
+data.getStringExtra(OtherActivity.KEY_USER_PASSWORD);
t.setText(str);
}

Toast.makeText(getApplicationContext(), "requestCode=" + requestCode + "::::" + "resultCode=" + resultCode, Toast.LENGTH_LONG).show();
}
}

------------------OtherActivity--------------------------------------------------------------------

public class OtherActivity extends Activity {

EditText eID ;
EditText ePASSWORD ;
Button b;

public static final String KEY_USER_ID = "USER_ID";
public static final String KEY_USER_PASSWORD = "USER_PASSWORD";

public static final int RESULT_OK = 111;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_other);

eID = (EditText)findViewById(R.id.user_ID);
ePASSWORD = (EditText)findViewById(R.id.user_PASSWORD);

b = (Button)findViewById(R.id.toMain_btn);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent in = new Intent();
in.putExtra(KEY_USER_ID, eID.getText().toString());
in.putExtra(KEY_USER_PASSWORD, ePASSWORD.getText().toString());
setResult(RESULT_OK,in);
finish();
}
});
}
}

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