java - 即使活动更改或应用程序关闭，使用共享首选项存储数据并显示它

Question

我有一个应用程序可以跟踪药物（例如吸入器）的医疗库存水平。我有一张吸入器的图片，然后是一个变量，其中包含剩余的剂量。其他吸入器和片剂也是如此。用户可以单击“减号”按钮，将剂量/片剂的数量减少 1。

我正在尝试保存用户离开屏幕的数字，例如，如果他们将剂量从 200 减少到 150，我希望在他们再次回到该活动时显示 150。

我采用的方法是使用共享首选项，但在测试时它不起作用，药物水平刚刚显示了它们在 OnCreate() 方法中设置的值。

这是我的代码：

public class ManageMedication extends AppCompatActivity {


Button minusblue;
Button minus2;
Button minus3;
Button minus4;

int inhalerlevelblue = 200;
int inhalerlevelbrown = 200;
int inhalerlevelred = 120;
int tabletlevel1 = 50;
int tabletlevel2 = 50;
int levelshowninhaler2;

int newlevel1;
int newlevel2;
int newlevel3;
int newlevel4;
String shownewlevel1;
String shownewlevel2;
String shownewlevel3;
String shownewlevel4;


TextView displaylevel;
TextView displaylevel2;
TextView displaylevel3;
TextView displaylevel4;

String showInhalerLevel;
String showInhalerLevel2;
String showtabletLevel2;
String showtabletLevel1;
String levelbrown;
String levelred;

Spinner spinnerInhalers;
ImageView imageView2;

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

    minusblue = findViewById(R.id.buttonminus);
    minus2 = findViewById(R.id.buttonminus2);
    minus3 = findViewById(R.id.buttonminus3);
    minus4 = findViewById(R.id.buttonminus4);


    showInhalerLevel = String.valueOf(inhalerlevelblue);
    showInhalerLevel2 = String.valueOf(levelshowninhaler2);
    showtabletLevel1 = String.valueOf(tabletlevel1);
    showtabletLevel2 = String.valueOf(tabletlevel2);
    levelbrown = String.valueOf(inhalerlevelbrown);
    levelred = String.valueOf(inhalerlevelred);

    spinnerInhalers = findViewById(R.id.spinnerInhalers);


    displaylevel = findViewById(R.id.textViewStockBlue);
    displaylevel2 = findViewById(R.id.textViewStock2);
    displaylevel3 = findViewById(R.id.textViewStock3);
    displaylevel4 = findViewById(R.id.textViewStock4);

    imageView2 = findViewById(R.id.imageView2);

    displaylevel.setText(showInhalerLevel);
    displaylevel3.setText(showtabletLevel1);
    displaylevel4.setText(showtabletLevel2);

    minusblue.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            inhalerlevelblue = inhalerlevelblue - 1;
            newlevel1 = inhalerlevelblue - 1;
            shownewlevel1 = String.valueOf(newlevel1);
            displaylevel.setText(shownewlevel1);
        }
    });

    minus2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            levelshowninhaler2 = levelshowninhaler2 - 1;
            newlevel2 = levelshowninhaler2 - 1;
            shownewlevel2 = String.valueOf(newlevel2);
            displaylevel2.setText(shownewlevel2);
        }
    });

    minus3.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            tabletlevel1 = tabletlevel1 - 1;
            newlevel3 = tabletlevel1 - 1;
            shownewlevel3 = String.valueOf(newlevel3);
            displaylevel3.setText(shownewlevel3);
        }
    });

    minus4.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            tabletlevel2 = tabletlevel2 - 1;
            newlevel4 = tabletlevel2 - 1;
            shownewlevel4 = String.valueOf(newlevel4);
            displaylevel4.setText(shownewlevel4);
        }
    });

    final ArrayAdapter<String> myAdapter2 = new ArrayAdapter<>(ManageMedication.this,
            android.R.layout.simple_spinner_dropdown_item, getResources().getStringArray(R.array.inhalers));
    myAdapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinnerInhalers.setAdapter(myAdapter2);

    spinnerInhalers.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int position2, long l) {


            switch (position2) {
                case 0:
                    imageView2.setImageResource(R.drawable.browninhaler);
                    displaylevel2.setText(levelbrown);
                    levelshowninhaler2 = inhalerlevelbrown;
                    break;
                case 1:
                    imageView2.setImageResource(R.drawable.redinhaler);
                    displaylevel2.setText(levelred);
                    levelshowninhaler2 = inhalerlevelred;
                    break;
                default:
                    break;
            }
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {
            String[] list = getResources().getStringArray(R.array.inhalers);

            spinnerInhalers.setSelection(Integer.parseInt(list[0]));
        }

    });

}

@Override
protected void onPause(){
    super.onPause();
    SharedPreferences.Editor editor = getSharedPreferences("myprefs", MODE_PRIVATE).edit();
    editor.putInt("newlevel1", newlevel1);
    editor.putInt("newlevel2", newlevel2);
    editor.putInt("newlevel3", newlevel3);
    editor.putInt("newlevel4", newlevel4);
    editor.putString("shownewlevel1", shownewlevel1);
    editor.putString("shownewlevel2", shownewlevel2);
    editor.putString("shownewlevel3", shownewlevel3);
    editor.putString("shownewlevel4", shownewlevel4);
    editor.apply();
}
@Override
protected void onResume(){
    super.onResume();
    SharedPreferences prefs = getSharedPreferences("myprefs", MODE_PRIVATE);
    String restoredText = prefs.getString("text", null);
    if (restoredText != null) {
        int retrieved1 = prefs.getInt("newlevel1", 0);//0 is the default value.
        int retrieved2 = prefs.getInt("newlevel2", 0);
        int retrieved3 = prefs.getInt("newlevel3", 0);
        int retrieved4 = prefs.getInt("newlevel4", 0);
        String retrievedlevel1 = prefs.getString("shownewlevel1", "No name defined");//"No name defined" is the default value.
        String retrievedlevel2 = prefs.getString("shownewlevel2", "No name defined");
        String retrievedlevel3 = prefs.getString("shownewlevel3", "No name defined");
        String retrievedlevel4 = prefs.getString("shownewlevel4", "No name defined");

        displaylevel.setText(retrievedlevel1);
        displaylevel2.setText(retrievedlevel2);
        displaylevel3.setText(retrievedlevel3);
        displaylevel4.setText(retrievedlevel4);

    }

}
@Override
protected void onDestroy(){
    super.onDestroy();
    SharedPreferences.Editor editor = getSharedPreferences("myprefs", MODE_PRIVATE).edit();
    editor.putInt("newlevel1", newlevel1);
    editor.putInt("newlevel2", newlevel2);
    editor.putInt("newlevel3", newlevel3);
    editor.putInt("newlevel4", newlevel4);
    editor.putString("shownewlevel1", shownewlevel1);
    editor.putString("shownewlevel2", shownewlevel2);
    editor.putString("shownewlevel3", shownewlevel3);
    editor.putString("shownewlevel4", shownewlevel4);
    editor.apply();
  }
}

如您所见，我正在尝试将新值和该值的字符串存储到共享首选项中，并在 OnResume() 中再次显示它们。

这是正确的方法还是任何人都可以帮助我？

谢谢

标签： javaandroidsharedpreferencesonresume