android - addPreferencesFromResource 使 sharedPreferences 不起作用

Question

所以可能是另一个新问题 :)

我有一个Activity、一个AppWidgetProvider 和一个PreferenceActivity。在 PreferenceActivity 中，我有一个 ListPreference，我用它来定义小部件的文本大小。 sharedPreferences 在主要 Activity 启动时加载没有问题，但是一旦 PreferenceActivity 运行，我就无法再检索 sharedPreference主要 Activity 中的正确值。我尝试直接在 PreferenceActivity 中检索 sharedPreference 值，同样的事情发生了:出于某种原因，当我尝试从 sharedPreferences 获取值时在我调用 addPreferencesFromResource(R.drawable.settings); 之前(在注释“测试 1”处)，它说:

"onStart() 1, size: small" and "Small works!"

即有用。但是当我尝试在资源调用之后检索值时(在注释“测试 2”处)，它说:

"onStart() 2, size: small" and "It doesn't work ..."

即它不起作用。我不知道为什么。显然它获得了 sharedPreference 的值，因为它表示当前 textWidgetSize 在这两种情况下都等于“小”，但出于某种原因它并不认为“小” =资源调用后的“小”。你们知道哪里出了问题吗？

这是 PreferenceActivity 代码:

package dk.mfoller.android.basicnote;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceActivity;
import android.preference.PreferenceManager;
import android.widget.Toast;
import dk.mfoller.android.basicnote.R;

public class BasicNoteSettings extends PreferenceActivity{

    String widgetTextSize = "small";
    boolean widgetLineCounter = true;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Calls a function to get the preferences
        getPrefs();

        // Test 1
        makeToast("onStart() 1, size: " + widgetTextSize);
        if(widgetTextSize == "small") {
            makeToast("Small works!");
        } else if(widgetTextSize == "medium") {
            makeToast("Medium works!");
        } else if(widgetTextSize == "large") {
            makeToast("Large works!");
        } else {
            makeToast("It doesn't work ...");
        }

        // Gets the preference layout from xml
        addPreferencesFromResource(R.drawable.settings);

        // Calls a function to get the preferences
        getPrefs();

        // Test 2
        makeToast("onStart() 2, size: " + widgetTextSize);
        if(widgetTextSize == "small") {
            makeToast("Small works!");
        } else if(widgetTextSize == "medium") {
            makeToast("Medium works!");
        } else if(widgetTextSize == "large") {
            makeToast("Large works!");
        } else {
            makeToast("It doesn't work ...");
        }

    }

    // A function to get the preferences    
    private void getPrefs() {
        // Gets data from the shared preferences
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
        widgetTextSize = prefs.getString("text_size_list", "small");
        widgetLineCounter = prefs.getBoolean("line_counter_cbox", true);
    }

    // A function to display a popup
    private void makeToast(String popup) {
        Toast.makeText(this, popup, Toast.LENGTH_SHORT).show();
    }

}

这是 xml 文档:

<?xml version="1.0" encoding="utf-8"?>

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    android:key="basicnote_settings"
    android:title="@string/settings_label">

    <PreferenceCategory android:title="Text size">
        <ListPreference android:key="text_size_list"
        android:title="Widget text size"
        android:summary="@string/text_size_summary"
        android:entries="@array/text_size_options"
        android:entryValues="@array/text_size_values"
        android:defaultValue="small" />
    </PreferenceCategory>

    <PreferenceCategory android:title="Other settings">
        <CheckBoxPreference android:key="line_counter_cbox"
            android:title="Line counter"
            android:summary="@string/hidden_lines_summary"
            android:defaultValue="true" />
    </PreferenceCategory>

</PreferenceScreen>

这是我的资源字符串:

<?xml version="1.0" encoding="utf-8"?>

<!-- Defines various resources -->
<resources>
    <string name="app_name">basicNote</string>
    <string name="note_hint">Tap to add some notes ...</string>
    <string name="fake_load">Loading notes ...</string>

    <string name="settings_label">basicNote settings</string>

    <string name="text_size_summary">Set the size of the widget text</string>
    <string-array name="text_size_options">
        <item>Small (12sp)</item>
        <item>Medium (13sp)</item>
        <item>Large (15sp)</item>
    </string-array>
    <string-array name="text_size_values">
        <item>small</item>
        <item>medium</item>
        <item>large</item>
    </string-array>

    <string name="hidden_lines_summary">Show/hide the number of lines not shown in the widget</string>
</resources>

Answer 1

您在 String 对象上使用 ==。请改用 .equals(yourString)。