Question

我目前正在构建一个应用程序，我正面临一个持久性问题。我有2个活动A和B.在A中我定义信息'aa'和B信息'bb'（'aa'通过意图提供给B）。当在B中并通过导航后退按钮（在操作栏中）回到A时，我希望A能够访问'bb'值，以便我可以基于它执行某些逻辑。对于你来说，保持这些数据在A中访问它的最佳方法是什么？在此先感谢您的时间和帮助。干杯，本杰明

Answer 1

您可以尝试使用onActivityResult。

在活动B中：

@Override
public void onBackPressed() {
   // super.onBackPressed();

    Intent intent = new Intent();
    //put something in intent
    setResult(RESULT_OK, intent);
    finish();
}

在活动A：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // TODO Auto-generated method stub
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 1) {
        if (resultCode == RESULT_OK) {

            //get extra...

        }
    }
}

Answer 2

从活动A启动活动B时，请使用startActivityForResult(Intent, int);代替正常startActivity(Intent);并覆盖活动A中的onActivityResult()

例如

public class ActivityA extends Activity{

    private static final int MY_REQUEST_CODE = 123;

    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);

        //Setup your activity and views...

        //Assuming that you start ActivityB when a button is clicked.
        btnExample.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){

                 Intent intent = new Intent(ActivityA.this, ActivityB.class);

                 //Setup your intent and put the data.

                 startActivityForResult(intent, MY_REQUEST_CODE);

            }
        });
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent backIntent)
    {
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode == RESULT_OK && requestCode == MY_REQUEST_CODE && backIntent != null){
            //Handle your logic here.
        }
    }
}

并在活动B中，覆盖onBackPressed

public class ActivityB extends Activity{

     //Setup your activity

     @Override
     public void onBackPressed()
     {
         Intent backIntent = new Intent();
         //Put the data to backIntent
         setResult(RESULT_OK, backIntent);
         super.onBackPressed();
     }

     //The rest of your code

}

建议在导航回应用程序时保持数据持久化

2 个答案: