Question

我可以在使用应用程序时保存选项，但每当我关闭应用程序并重新启动它时，选项再次为空。我哪里错了？它始终加载默认值＆＃34; 0＆＃34;而不是记住最后的选择。

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
        final SharedPreferences.Editor editor = preferences.edit();
        SharedPreferences choiceSettings = getSharedPreferences("currentChoice", 0);
        final int[] currentChoice = {choiceSettings.getInt("currentChoice", 0)};
        final CharSequence[] items = {"AT&T", "Tmobile", "Verizon", "Sprint", "Other"};
        // Decide which carrier, so we can apply the correct forwarding code.
        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Select your carrier");
        builder.setIcon(R.drawable.ic_launcher);
        builder.setSingleChoiceItems(items, currentChoice[0],
                new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int item) {
                        // TODO Auto-generated method stub
                        switch (item) {
                            case 0:
                                Toast.makeText(getApplicationContext(),
                                        items[item], Toast.LENGTH_SHORT).show();
                                // Your code when first option seletced
                                currentChoice[0] = 0;
                                editor.putInt(String.valueOf(currentChoice[0]), 0);
                                editor.putString("fCode", "*67*");
                                editor.apply();
                                break;
                            case 1:
                                // Your code when 2nd option seletced
                                Toast.makeText(getApplicationContext(),
                                        items[item], Toast.LENGTH_SHORT).show();
                                currentChoice[0] = 1;
                                editor.putInt(String.valueOf(currentChoice[0]), 0);
                                editor.putString("fCode", "*67*");
                                editor.apply();
                                break;
                            case 2:
                                // Your code when 2nd option seletced
                                Toast.makeText(getApplicationContext(),
                                        items[item], Toast.LENGTH_SHORT).show();
                                currentChoice[0] = 2;
                                editor.putInt(String.valueOf(currentChoice[0]), 0);
                                editor.putString("fCode", "*67*");
                                editor.apply();
                                break;
                        }
                        dialog.cancel();
                    }
                });
        AlertDialog alert = builder.create();
        alert.show();
    }

Answer 1

您正在使用两个共享首选项容器，默认容器和自定义容器容器。仅使用默认值。

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this); 
final SharedPreferences.Editor editor = preferences.edit();
final int[] currentChoice = {preferences.getInt("currentChoice", 0)};

Answer 2

在开头（第4行），您尝试加载名为"currentChoice"的变量：

final int[] currentChoice = {choiceSettings.getInt("currentChoice", 0)};

通常，您使用editor.putInt(String key, int value)保存变量。因此key是用于保存变量的名称。

写作时

currentChoice[0] = 0;
editor.putInt(String.valueOf(currentChoice[0]), 0);

String.valueOf(currentChoice[0])成为＆＃34; 0＆＃34;。将int 0保存到名为＆＃34; 0＆＃34;的变量中。所以将第二行改为

editor.putInt("currentChoice", currentChoice[0]);

在Android警报对话框中保存单选按钮选择

2 个答案: