java - 检索微调器选定的项目以在条件语句中使用

Question

我能够保存微调器所选项目的状态。我只是在发送和检索要在下一个 Activity 的 if 语句中使用的选定项目时遇到问题。

我知道我必须使用共享首选项，但在旋转项目方面我遇到了一些麻烦。

这是我的代码:

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



    LastSelectedItem = getSharedPreferences("PriorSelected", MODE_PRIVATE);

    go_back_btn = (Button) findViewById(R.id.go_back_btn);
    themeSpinner = (Spinner) findViewById(R.id.themeSpinner);


    go_back_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            LastSelectedItem = getSharedPreferences("PriorSelected", MODE_PRIVATE);
            SharedPreferences.Editor editor = LastSelectedItem.edit();
            editor.apply();
            Intent intent = new Intent(getApplicationContext(), home.class);
            startActivity(intent);
        }
    });


    int LastSelection = LastSelectedItem.getInt("LastSelection", 0);
    editor = LastSelectedItem.edit();


    ArrayAdapter<CharSequence> themeAdapter = ArrayAdapter.createFromResource(settings.this, R.array.theme_array, android.R.layout.simple_spinner_item);
    themeAdapter.setDropDownViewResource(android.R.layout.simple_spinner_item);

    themeSpinner.setAdapter(themeAdapter);
    themeSpinner.setSelection(LastSelection);


    themeSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            editor.putInt("LastSelection", position).apply();


        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {

        }
    });

}
}

Answer 1

SharedPreferences settings = getSharedPreferences("app_pref", 0);
SharedPreferences.Editor editor = settings.edit();

 themeSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                  //To save
editor.putInt("position",position);
editor.commit();


                }

                @Override
                public void onNothingSelected(AdapterView<?> parent) {

                }
            });



   //To retrieve in next activity
   SharedPreferences settings = getSharedPreferences("app_pref", 0);
   int snowDensity = settings.getInt("position", -1); //0 is the default value

您可以将值存储到 int 并将其传递给下一个 Activity ，而不是共享首选项。

 int position=-1;   

 themeSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                position=position;


            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                position=-1;
            }
        });


       go_back_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                Intent intent = new Intent(getApplicationContext(), home.class);
               intent.putExtra("position", position);
                startActivity(intent);
            }
        });

第二个 Activity :

int position= getIntent().getIntExtra("position", -1);