如何在首选项摘要中显示 Android 首选项的当前值? [英] How do I display the current value of an Android Preference in the Preference summary?

问题描述

这必须经常出现.

当用户在 Android 应用中编辑首选项时，我希望他们能够在 Preference 摘要中看到当前设置的首选项值.

When the user is editing preferences in an Android app, I'd like them to be able to see the currently set value of the preference in the Preference summary.

示例:如果我有一个丢弃旧邮件"的首选项设置，该设置指定需要清理邮件的天数.在 PreferenceActivity 我希望用户看到:

Example: if I have a Preference setting for "Discard old messages" that specifies the number of days after which messages need to be cleaned up. In the PreferenceActivity I'd like the user to see:

丢弃旧消息" <- 标题

在 x 天后清理邮件" <- summary 其中 x 是当前的 Preference 值

"Clean up messages after x days" <- summary where x is the current Preference value

额外的功劳:使其可重复使用，因此我可以轻松地将其应用于我的所有首选项，无论它们的类型如何(以便它以最少的编码与 EditTextPreference、ListPreference 等一起使用).

Extra credit: make this reusable, so I can easily apply it to all my preferences regardless of their type (so that it work with EditTextPreference, ListPreference etc. with minimal amount of coding).

推荐答案

这是我的解决方案... FWIW

Here is my solution... FWIW

package com.example.PrefTest;

import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.os.Bundle;
import android.preference.EditTextPreference;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.preference.PreferenceGroup;
import android.preference.PreferenceManager;

public class Preferences extends PreferenceActivity implements
        OnSharedPreferenceChangeListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences);
        PreferenceManager.setDefaultValues(Preferences.this, R.xml.preferences,
            false);
        initSummary(getPreferenceScreen());
    }

    @Override
    protected void onResume() {
        super.onResume();
        // Set up a listener whenever a key changes
        getPreferenceScreen().getSharedPreferences()
                .registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    protected void onPause() {
        super.onPause();
        // Unregister the listener whenever a key changes
        getPreferenceScreen().getSharedPreferences()
                .unregisterOnSharedPreferenceChangeListener(this);
    }

    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
            String key) {
        updatePrefSummary(findPreference(key));
    }

    private void initSummary(Preference p) {
        if (p instanceof PreferenceGroup) {
            PreferenceGroup pGrp = (PreferenceGroup) p;
            for (int i = 0; i < pGrp.getPreferenceCount(); i++) {
                initSummary(pGrp.getPreference(i));
            }
        } else {
            updatePrefSummary(p);
        }
    }

    private void updatePrefSummary(Preference p) {
        if (p instanceof ListPreference) {
            ListPreference listPref = (ListPreference) p;
            p.setSummary(listPref.getEntry());
        }
        if (p instanceof EditTextPreference) {
            EditTextPreference editTextPref = (EditTextPreference) p;
            if (p.getTitle().toString().toLowerCase().contains("password"))
            {
                p.setSummary("******");
            } else {
                p.setSummary(editTextPref.getText());
            }
        }
        if (p instanceof MultiSelectListPreference) {
            EditTextPreference editTextPref = (EditTextPreference) p;
            p.setSummary(editTextPref.getText());
        }
    }
}

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