@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。

除了上面提到的答案，还有另一种方法，假设你有两个类，A类和B类。

类A你做了一些活动，比如选择复选框，打印出一些数据和意图到类B。 类B，你想传递多个值给类A，并保持类A之前的状态，你可以使用，尝试这种替代方法或下载源代码来演示这一点

http://whats-online.info/science-and-tutorials/125/Android-maintain-the-previous-state-of-activity-on-intent/

or

http://developer.android.com/reference/android/content/Intent.html

你可以试试这个:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {

        finish();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

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

如果你想点击返回按钮，然后简单地放

bbsubmit.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        onBackPressed();
    }
});

可以显式调用onBackPressed是最简单的方法 参考返回到上一个活动的详细信息

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。