有一些情况可以回到你之前的活动:

情况1:如果你想把结果带回你之前的活动，那么 ActivityA.java

 Intent intent = new Intent(ActivityA.this, FBHelperActivity.class);
               startActivityForResult(intent,2);

FBHelperActivity.java

 Intent returnIntent = new Intent();
 setResult(RESULT_OK, returnIntent);
 finish();

案例2:ActivityA——> FBHelperActivity---->ActivityA

ActivityA.java

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

FBHelperActivity.java

after getting of result call finish();
 By this way your second activity will finish and because 
 you did not call finish() in your first activity then
 automatic first activity is in back ground, will visible.

 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
      int id = item.getItemId();

      if ( id == android.R.id.home ) {
          finish();
          return true;
      }

      return super.onOptionsItemSelected(item);
 }

尝试一下，它既可以在工具栏返回按钮作为硬件返回按钮。

您是否想要控制后退按钮的行为?您可以通过以下两种方法之一重写后退按钮(以转到特定的活动)。

Android 1.6及以下版本:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)  {
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
        // do something on back.
        return true;
    }

    return super.onKeyDown(keyCode, event);
}

或者如果你只支持android2.0或更高版本:

@Override
public void onBackPressed() {
    // do something on back.
    return;
}

详情请访问:http://android-developers.blogspot.com/2009/12/back-and-other-hard-keys-three-stories.html

试着活动#完成()。这或多或少是后退按钮默认的功能。

Android活动存储在活动堆栈中。回到以前的活动可能意味着两件事。

You opened the new activity from another activity with startActivityForResult. In that case you can just call the finishActivity() function from your code and it'll take you back to the previous activity. Keep track of the activity stack. Whenever you start a new activity with an intent you can specify an intent flag like FLAG_ACTIVITY_REORDER_TO_FRONT or FLAG_ACTIVITY_PREVIOUS_IS_TOP. You can use this to shuffle between the activities in your application. Haven't used them much though. Have a look at the flags here: http://developer.android.com/reference/android/content/Intent.html

正如注释中提到的，如果活动是用startActivity()打开的，那么可以用finish()关闭它。 如果你想使用向上按钮，你可以在onOptionsSelected(MenuItem item)方法中捕捉到，检查android.R.id.home的项目ID，而不是评论中提到的R.id.home。

通过单击返回按钮从一个活动返回到另一个活动，使用下面给出的代码，使用当前活动名称，然后使用目标活动。

@Override
public void onBackPressed() {
    // do something on back.
    startActivity(new Intent(secondActivity.this, MainActivity.class));
    return;
}