Question

我有一个简单的程序，可以从活动B中更改活动A的背景。当您更改背景时，您需要刷新活动A以便更改背景，在查看stackoverflow之后，最简单的方法就是调用recreate（）。

我不确定我是在调用错误还是在错误的区域，但最终发生的事情是，当应用程序运行并最终崩溃时，它会循环以下错误 -

02-01 13:23:53.358 17302-17302/com.package.www.randomapp E/ViewRootImpl: sendUserActionEvent() mView == null

这是活动A的代码

@Override
 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mainmenu);
    backgroundChanger();
    recreate();
}

   public void backgroundChanger(){
    SharedPreferences sharedGradients = getSharedPreferences("gradientInfo", Context.MODE_PRIVATE);
    int backgroundGrad = sharedGradients.getInt("backgroundGradient", 0);


    if (backgroundGrad == 0){
        MMBackground.setBackgroundResource(R.drawable.blackgreengradiant);




    }
    if (backgroundGrad == 1){
        MMBackground.setBackgroundResource(R.drawable.blueblackgradiant);


    }
    if (backgroundGrad == 2){
        MMBackground.setBackgroundResource(R.drawable.goldblackgradiant);


    }

和活动B

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

 public void variableHandler() {  

    MainMenuBackgroundBtn.setOnClickListener(new View.OnClickListener() { 
        @Override
        public void onClick(final View v) {

            final SharedPreferences[] sharedGradients = {getSharedPreferences("gradientInfo", Context.MODE_PRIVATE)};
            final SharedPreferences.Editor[] editor1 = {sharedGradients[0].edit()};

            final SharedPreferences[] sharedBoolean = {getSharedPreferences("binaryPoint", Context.MODE_PRIVATE)};
            final SharedPreferences.Editor[] editorBinary = {sharedBoolean[0].edit()};

            final PopupMenu popup = new PopupMenu(getApplicationContext(), v);
            popup.inflate(R.menu.menu_background_gradiant_setter);
            popup.show();


            popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                @Override
                public boolean onMenuItemClick(MenuItem item) {

                    switch (item.getItemId()) {
                        case R.id.item1:
                            Toast.makeText(OptionsMenu.this, "Blue and black gradient", Toast.LENGTH_SHORT).show();

                            editorBinary[0] = sharedBoolean[0].edit();
                            editorBinary[0].putInt("binaryPoint", 1);

                            editor1[0] = sharedGradients[0].edit();
                            editor1[0].putInt("backgroundGradient", 1);
                            editor1[0].apply();



                            return true;

                        case R.id.item2:
                            Toast.makeText(OptionsMenu.this, "Gold and black gradient", Toast.LENGTH_SHORT).show();
                            editorBinary[0] = sharedBoolean[0].edit();
                            editorBinary[0].putInt("binaryPoint", 1);

                            editor1[0] = sharedGradients[0].edit();
                            editor1[0].putInt("backgroundGradient", 2);
                            editor1[0].apply();
                            return true;
    }
}

Answer 1

问题是你在Activity的recreate()方法中调用onCreate()而没有任何会产生无限循环的条件。保留一个变量来跟踪是否重新创建活动。

private static boolean alreadyRecreated = false;
//You can add some extra conditions here if you want.
if(!alreadyRecreated){
  recreate();
   alreadyRecreated = true;
}

Answer 2

recreate();会导致您的活动被重新创建。

即onCreate被调用。因为，你在onCreate方法中添加了recreate();，它会运行到无限循环并崩溃。

为什么重新创建循环无限？

2 个答案: