如何保存 Android 的可见性

Question

我尝试保存卡片视图的可见性状态，起初我的视图消失了，但是如果用户按下按钮，卡片视图就会显示。有人可以帮助我并告诉我如何存储可见性，我找不到有关此主题的任何内容太感谢了。我尝试了 shardPrefs 但不起作用@Overrideprotected void onCreate(final Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    cv1= (CardView) findViewById(R.id.cv1);    cv2= (CardView) findViewById(R.id.cv2);    cv3= (CardView) findViewById(R.id.cv3);    cv4= (CardView) findViewById(R.id.cv4);    cv5= (CardView) findViewById(R.id.cv5);    cv6= (CardView) findViewById(R.id.cv6);    cv7= (CardView) findViewById(R.id.cv7);    cv8= (CardView) findViewById(R.id.cv8);    cv9= (CardView) findViewById(R.id.cv9);    AddBar = findViewById(R.id.AddBar);    AddVoorraad =findViewById(R.id.AddVoorraad);    AddBar.setOnClickListener(new View.OnClickListener() {        @Override        public void onClick(View v) {            clickcount = clickcount + 1;            if (clickcount == 1) {                cv1.setVisibility(View.VISIBLE);            }            if (clickcount == 2) {                cv2.setVisibility(View.VISIBLE);            }            if (clickcount == 3) {                cv3.setVisibility(View.VISIBLE);            }            if (clickcount == 4) {                cv4.setVisibility(View.VISIBLE);            }            if (clickcount == 5) {                cv5.setVisibility(View.VISIBLE);            }            if (clickcount == 6) {                cv6.setVisibility(View.VISIBLE);            }            if (clickcount==7 ){                cv7.setVisibility(View.VISIBLE);            }        }    });    AddVoorraad.setOnClickListener(new View.OnClickListener() {        @Override        public void onClick(View v) {            clickcountV=clickcountV+1;            if (clickcountV==1) {                cv8.setVisibility(View.VISIBLE);            }            if (clickcount==2) {                cv9.setVisibility(View.VISIBLE);            }        }    });

Answer 1

尝试根据条件存储每个CardView内部的可见性。SharedPrefs并在 CardView 初始化期间检索并设置它们。检查下面的代码：

SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

int isVisible = sharedPreferences.getInt("cv1", View.GONE);

cv1.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv2", View.GONE);

cv2.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv3", View.GONE);

cv3.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv4", View.GONE);

cv4.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv5", View.GONE);

cv5.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv6", View.GONE);

cv6.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv7", View.GONE);

cv7.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv8", View.GONE);

cv8.setVisibility(isVisible);

isVisible = sharedPreferences.getInt("cv9", View.GONE);

cv9.setVisibility(isVisible);

AddBar.setOnClickListener(new View.OnClickListener() {

    @Override

    public void onClick(View v) {

        clickcount = clickcount + 1;

        if (clickcount == 1) {

            cv1.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv1", View.VISIBLE).commit();

        }

        if (clickcount == 2) {

            cv2.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv2", View.VISIBLE).commit();

        }

        if (clickcount == 3) {

            cv3.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv3", View.VISIBLE).commit();

        }

        if (clickcount == 4) {

            cv4.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv4", View.VISIBLE).commit();

        }

        if (clickcount == 5) {

            cv5.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv5", View.VISIBLE).commit();

        }

        if (clickcount == 6) {

            cv6.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv6", View.VISIBLE).commit();

        }

        if (clickcount==7 ){

            cv7.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv7", View.VISIBLE).commit();

        }

    }

});

AddVoorraad.setOnClickListener(new View.OnClickListener() {

    @Override

    public void onClick(View v) {

        clickcountV=clickcountV+1;

        if (clickcountV==1) {

            cv8.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv8", View.VISIBLE).commit();

        }

        if (clickcountV==2) {

            cv9.setVisibility(View.VISIBLE);

            sharedPreferences.edit().putInt("cv9", View.VISIBLE).commit();

        }

    }

});

Answer 2

当配置更改（旋转）时，您可以从 onSaveInstanceState 检索值，但是当您关闭应用程序（后退按钮）时，您需要从持久性存储中检索状态，例如共享首选项。

Answer 3

我不知道你到底尝试了什么，但如果你想做的只是存储状态以供以后使用，你当然可以使用 SharedPreferences 来实现这一点。您可以执行以下操作将状态保存为表示状态的字符串：

SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences();

SharedPreferences.Editor editor = prefs.edit();  

editor.putString("cv1_visibility", "VISIBLE");

editor.putString("cv2_visibility", "INVISIBLE");

editor.putString("cv3_visivility", "GONE");

...

editor.commit();

然后你可以像这样读取这些值：

SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences();

String cv1_state = prefs.getString("cv1_visibility", "NOT_FOUND");

String cv2_state = prefs.getString("cv2_visibility", "NOT_FOUND");

String cv3_state = prefs.getString("cv3_visibility", "NOT_FOUND");

...

然后根据活动开始时的状态进行适当的处理。请注意，getString()有一个defValue参数（第二个参数），该参数是首选项不存在时要返回的值。

编辑：您可以选择将它们存储为 int，但请注意其中一些常量不是 int。看看这个就明白我的意思了：https ://developer.android.com/reference/android/view/View