Question

我正在教自己如何使用Fragments和SharedPreferences。我正在创建一个使用导航抽屉在片段之间进行切换的应用。

在片段A中，我有8个切换按钮。当用户为B留下片段A然后返回时，我需要切换为保持这种状态的切换按钮，直到用户手动重置为止。切换和重置工作正常，但是我在多次尝试使SharedPref保持按钮状态时没有成功。

我认为这可能是个问题，因为每次选择菜单项时它都会调用“new”。如果是这样，我该如何解决它？

 public boolean onNavigationItemSelected(@NonNull MenuItem item) {

        switch(item.getItemId()){
            case R.id.nav_carb:
               getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainer,
                       new  CarbFragment()).commit();
                break;

MainActivity ：

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    private DrawerLayout drawer;
    ToggleButton toggleButton, toggleButton1, toggleButton2, toggleButton3, toggleButton4, toggleButton5, toggleButton6, toggleButton7;
    boolean selected, tb;
    SharedPreferences preferences;



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

        android.support.v7.widget.Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        drawer = findViewById(R.id.drawer_layout);
        NavigationView navigationView =findViewById(R.id.navView);
        navigationView.setNavigationItemSelectedListener(this);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);

        drawer.addDrawerListener(toggle);
        toggle.syncState();

        preferences = getSharedPreferences("checkedState", Context.MODE_PRIVATE);
        if(preferences.contains("tbpref")){
            selected = preferences.getBoolean("tbpref", true);
        }
       }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {

        switch(item.getItemId()){
            case R.id.nav_carb:
               getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainer,
                       new  CarbFragment()).commit();
                break;

            case R.id.nav_cal:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainer,
                        new CalFragment()).commit();
                break;
        }
        drawer.closeDrawer(GravityCompat.START);

        return true;
    }

FragmentA

public class CarbFragment extends Fragment {

ToggleButton toggleButton, toggleButton1, toggleButton2, toggleButton3, toggleButton4, toggleButton5, toggleButton6, toggleButton7;
Button reset;
boolean selected, tb;
SharedPreferences preferences;


@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    ConstraintLayout rootView = (ConstraintLayout) inflater.inflate(R.layout.fragment_carb_count, container, false);


    toggleButton = rootView.findViewById(R.id.toggleButton);
    toggleButton1 = rootView.findViewById(R.id.toggleButton1);
    toggleButton2 = rootView.findViewById(R.id.toggleButton2);
    toggleButton3 = rootView.findViewById(R.id.toggleButton3);
    toggleButton4 = rootView.findViewById(R.id.toggleButton4);
    toggleButton5 = rootView.findViewById(R.id.toggleButton5);
    toggleButton6 = rootView.findViewById(R.id.toggleButton6);
    toggleButton7 = rootView.findViewById(R.id.toggleButton7);
    reset = rootView.findViewById(R.id.button);

    reset.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {
           toggleButton.setChecked(false);
           toggleButton.setBackgroundColor(Color.rgb(255, 153, 153));
           toggleButton1.setChecked(false);
           toggleButton1.setBackgroundColor(Color.rgb(255, 219, 153));
           toggleButton2.setChecked(false);
           toggleButton2.setBackgroundColor(Color.rgb(255, 255, 153));
           toggleButton3.setChecked(false);
           toggleButton3.setBackgroundColor(Color.rgb(153, 255, 153));
           toggleButton4.setChecked(false);
           toggleButton4.setBackgroundColor(Color.rgb(153, 153, 255));
           toggleButton5.setChecked(false);
           toggleButton5.setBackgroundColor(Color.rgb(255, 153, 255));
           toggleButton6.setChecked(false);
           toggleButton6.setBackgroundColor(Color.rgb(255, 255, 255));
           toggleButton7.setChecked(false);
           toggleButton7.setBackgroundColor(Color.rgb(204, 204, 204));

           Toast toast = Toast.makeText(getContext(), "Ready to go again!", Toast.LENGTH_SHORT);
           toast.show();
       }
   });



    toggleButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "Nom Nom Nom", Toast.LENGTH_SHORT);
            toast.show();

            if (toggleButton.isChecked()) {
                SharedPreferences.Editor editor = preferences.edit();
                editor.putBoolean("tbpref", true);
                editor.apply();
            }
            else{
                SharedPreferences.Editor editor = preferences.edit();
                editor.putBoolean("tbpref", false);
                editor.apply();
            }


        }
    });
    toggleButton1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton1.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "You've got this!", Toast.LENGTH_SHORT);
            toast.show();
        }
    });


    toggleButton2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton2.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "Look at you go!!!", Toast.LENGTH_SHORT);
            toast.show();
        }
    });
    toggleButton3.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton3.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "You are crushing this!", Toast.LENGTH_SHORT);
            toast.show();
        }
    });

    toggleButton4.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton4.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "Killin' IT!", Toast.LENGTH_SHORT);
            toast.show();
        }
    });

    toggleButton5.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton5.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "Carbs don't control you!", Toast.LENGTH_SHORT);
            toast.show();
        }
    });

    toggleButton6.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton6.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "You're so awesome", Toast.LENGTH_SHORT);
            toast.show();
        }
    });

    toggleButton7.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            toggleButton7.setBackgroundColor(Color.DKGRAY);

            Toast toast = Toast.makeText(getContext(), "Kickin' butt and taking names", Toast.LENGTH_SHORT);
            toast.show();
        }
    });
    return rootView;
}

}

非常感谢能提供的任何帮助。我在这里看了几个答案，但似乎没有一个适合我的问题。我试着实现一些答案，但它们似乎也不适合我。谢谢。

Answer 1

您只能将状态写入共享首选项，而不是在片段内从它们中读取它。为了实现这一目标，您必须在onCreateView方法中执行以下操作：

boolean isChecked = preferences.getBoolean("tbpref");
toggleButton.setChecked(isChecked);

ToggleButtons Fragments SharedPref

1 个答案: