Question

我正在编写一个需要基于TimePicker的首选项（实际上是两个）的应用程序，并从Android Programming Tutorials书中刷了一些（Apache许可的）代码。我把它修改得更好一些，但有一件事令我困惑。

我还没有在实际设备上尝试过它，但是在仿真器上它现在考虑了24小时时间显示的系统设置，清除了对TimePicker对话框的关注，这样即使手动编辑而不是使用时间也会被读取箭头键和 - 有问题的部分 - 在PreferenceScreen中显示所选时间。

问题在于我已经在模拟器中尝试了这个API级别3,4,7和10，并且它只在10中完全正确工作。在早期版本的模拟器中，如果我在PreferenceScreen中放入一个复选框两个TimePreferences，每次切换复选框时，两个TimePreferences中的TextView都会切换位置。因此，如果我第一次启动应用程序时单击复选框，则开始时间看起来像晚上10点，停止时间看起来像早上8点（即使我点击首选项时，适当的时间显示在TimePicker中）。

有更好的方法吗？最好是一种优雅的方式，以便整个类是自包含的，我不需要在仅适用于类的XML文件中创建布局？或者有办法解决/修复此行为？我还想避免使用setSummary，以便仍然有机会向首选项添加摘要。我的大部分实验都在使用布局代码在onCreateView中，但我无法完全正确地工作。无论我使用RelativeLayout还是LinearLayout，这似乎都会发生。

完整代码如下：

package test.android.testproject2;

//imports...

public class TimePreference extends DialogPreference {
    private int lastHour=0;
    private int lastMinute=0;
    private boolean is24HourFormat;
    private TimePicker picker=null;
    private TextView timeDisplay;

    public TimePreference(Context ctxt) {
        this(ctxt, null);
    }

    public TimePreference(Context ctxt, AttributeSet attrs) {
        this(ctxt, attrs, 0);
    }

    public TimePreference(Context ctxt, AttributeSet attrs, int defStyle) {
        super(ctxt, attrs, defStyle);

        is24HourFormat = DateFormat.is24HourFormat(ctxt);
        setPositiveButtonText("Set");
        setNegativeButtonText("Cancel");
    }

    @Override
    public String toString() {
        if(is24HourFormat) {
            return ((lastHour < 10) ? "0" : "")
                    + Integer.toString(lastHour)
                    + ":" + ((lastMinute < 10) ? "0" : "")
                    + Integer.toString(lastMinute);
        } else {
            int myHour = lastHour % 12;
            return ((myHour == 0) ? "12" : ((myHour < 10) ? "0" : "") + Integer.toString(myHour))
                    + ":" + ((lastMinute < 10) ? "0" : "") 
                    + Integer.toString(lastMinute) 
                    + ((lastHour >= 12) ? " PM" : " AM");
        }
    }

    @Override
    protected View onCreateDialogView() {
        picker=new TimePicker(getContext().getApplicationContext());
        return(picker);
    }

    @Override
    protected void onBindDialogView(View v) {
        super.onBindDialogView(v);
        picker.setIs24HourView(is24HourFormat);
        picker.setCurrentHour(lastHour);
        picker.setCurrentMinute(lastMinute);
    }

    @Override
    protected View onCreateView (ViewGroup parent) {
         View prefView = super.onCreateView(parent);
         LinearLayout layout = new LinearLayout(parent.getContext());
         LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.FILL_PARENT, 2);
         layout.addView(prefView, lp);
         timeDisplay = new TextView(parent.getContext());
         timeDisplay.setGravity(Gravity.BOTTOM | Gravity.RIGHT);
         timeDisplay.setText(toString());
         LinearLayout.LayoutParams lp2 = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.FILL_PARENT, 1);
         layout.addView(timeDisplay, lp2);
         return layout;
    }

    @Override
    protected void onDialogClosed(boolean positiveResult) {
        super.onDialogClosed(positiveResult);

        if (positiveResult) {
            picker.clearFocus();
            lastHour=picker.getCurrentHour();
            lastMinute=picker.getCurrentMinute();

            String time=String.valueOf(lastHour)+":"+String.valueOf(lastMinute);

            if (callChangeListener(time)) {
                persistString(time);
                timeDisplay.setText(toString());
            }
        }
    }

    @Override
    protected Object onGetDefaultValue(TypedArray a, int index) {
        return(a.getString(index));
    }

    @Override
    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
        String time=null;

        if (restoreValue) {
            if (defaultValue==null) {
                time=getPersistedString("00:00");
            }
            else {
                time=getPersistedString(defaultValue.toString());
            }
        }
        else {
            if (defaultValue==null) {
                time="00:00";
            }
            else {
                time=defaultValue.toString();
            }
            if (shouldPersist()) {
                persistString(time);
            }
        }

        String[] timeParts=time.split(":");
        lastHour=Integer.parseInt(timeParts[0]);
        lastMinute=Integer.parseInt(timeParts[1]);;
    }
}

示例首选项布局如下：

<?xml version="1.0" encoding="UTF-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    <PreferenceCategory android:title="@string/preferences_time_title">
        <test.android.testproject2.TimePreference
            android:key="preferences_start_time"
            android:showDefault="true"
            android:defaultValue="08:00"
            android:summary="When to start"
            android:title="@string/preferences_start_time"/>
        <test.android.testproject2.TimePreference
            android:key="preferences_stop_time"
            android:showDefault="true"
            android:defaultValue="22:00"
            android:summary="When to stop"
            android:title="@string/preferences_stop_time"/>
    </PreferenceCategory>
    <PreferenceCategory android:title="@string/preferences_options_title">
        <CheckBoxPreference
            android:key="preferences_enabled"
            android:defaultValue="false"
            android:title="@string/preferences_enabled"/>
    </PreferenceCategory>
</PreferenceScreen>

截图：

Default settings

Checked settings

这发生在API 3,4和7的模拟器上。我也在10上尝试过它并且它可以正常工作。

更新：它在带有API 8的模拟器上也能正常工作（2.2 / Froyo）。

更新2：我已经重写了onCreateView方法，如下所示。它仍然以同样的方式失败，但渲染效率更高，我相信它的行为更接近Android文档中指定的要求。

    @Override
    protected View onCreateView (ViewGroup parent) {
         ViewGroup prefView = (ViewGroup) super.onCreateView(parent);
         View widgetLayout;
         int childCounter = 0;
         do {
             widgetLayout = prefView.getChildAt(childCounter);
             childCounter++;
         } while (widgetLayout.getId() != android.R.id.widget_frame); 
         timeDisplay = new TextView(widgetLayout.getContext());
         timeDisplay.setText(toString());
         ((ViewGroup) widgetLayout).addView(timeDisplay);
         return prefView;
    }

我的下一步是开始登录onCreateView，onBindView和getView，看看它们是如何被调用的以及视图内部发生了什么。如果有人在此期间提出任何想法，请告诉我！

Answer 1

我已经弄明白了并修复了它。它现在适用于从Cupcake（1.5 - 3级）到Gingerbread（2.3.3 - 10级）的API的各个级别。代码如下。请注意，原始代码是在问题中指定的Apache许可。我特此将所有修改都用于公共领域。

package test.android.testproject2;

import android.content.Context;
import android.content.res.TypedArray;
import android.preference.DialogPreference;
import android.text.format.DateFormat;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.TimePicker;

public class TimePreference extends DialogPreference {
    protected int lastHour=0;
    protected int lastMinute=0;
    protected boolean is24HourFormat;
    protected TimePicker picker=null;
    protected TextView timeDisplay;

    public TimePreference(Context ctxt) {
        this(ctxt, null);
    }

    public TimePreference(Context ctxt, AttributeSet attrs) {
        this(ctxt, attrs, 0);
    }

    public TimePreference(Context ctxt, AttributeSet attrs, int defStyle) {
        super(ctxt, attrs, defStyle);

        is24HourFormat = DateFormat.is24HourFormat(ctxt);
        setPositiveButtonText("Set");
        setNegativeButtonText("Cancel");
    }

    @Override
    public String toString() {
        if(is24HourFormat) {
            return ((lastHour < 10) ? "0" : "")
                    + Integer.toString(lastHour)
                    + ":" + ((lastMinute < 10) ? "0" : "")
                    + Integer.toString(lastMinute);
        } else {
            int myHour = lastHour % 12;
            return ((myHour == 0) ? "12" : ((myHour < 10) ? "0" : "") + Integer.toString(myHour))
                    + ":" + ((lastMinute < 10) ? "0" : "") 
                    + Integer.toString(lastMinute) 
                    + ((lastHour >= 12) ? " PM" : " AM");
        }
    }

    @Override
    protected View onCreateDialogView() {
        picker=new TimePicker(getContext().getApplicationContext());
        return(picker);
    }

    @Override
    protected void onBindDialogView(View v) {
        super.onBindDialogView(v);
        picker.setIs24HourView(is24HourFormat);
        picker.setCurrentHour(lastHour);
        picker.setCurrentMinute(lastMinute);
    }

    @Override
    public void onBindView(View view) {
        View widgetLayout;
        int childCounter = 0;
        do {
            widgetLayout = ((ViewGroup) view).getChildAt(childCounter);
            childCounter++;
        } while (widgetLayout.getId() != android.R.id.widget_frame); 
        ((ViewGroup) widgetLayout).removeAllViews();
        timeDisplay = new TextView(widgetLayout.getContext());
        timeDisplay.setText(toString());
        ((ViewGroup) widgetLayout).addView(timeDisplay);
        super.onBindView(view);
    }

    @Override
    protected void onDialogClosed(boolean positiveResult) {
        super.onDialogClosed(positiveResult);

        if (positiveResult) {
            picker.clearFocus();
            lastHour=picker.getCurrentHour();
            lastMinute=picker.getCurrentMinute();

            String time=String.valueOf(lastHour)+":"+String.valueOf(lastMinute);

            if (callChangeListener(time)) {
                persistString(time);
                timeDisplay.setText(toString());
            }
        }
    }

    @Override
    protected Object onGetDefaultValue(TypedArray a, int index) {
        return(a.getString(index));
    }

    @Override
    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
        String time=null;

        if (restoreValue) {
            if (defaultValue==null) {
                time=getPersistedString("00:00");
            }
            else {
                time=getPersistedString(defaultValue.toString());
            }
        }
        else {
            if (defaultValue==null) {
                time="00:00";
            }
            else {
                time=defaultValue.toString();
            }
            if (shouldPersist()) {
                persistString(time);
            }
        }

        String[] timeParts=time.split(":");
        lastHour=Integer.parseInt(timeParts[0]);
        lastMinute=Integer.parseInt(timeParts[1]);;
    }
}

基于TimePicker的DialogPreference的布局

1 个答案: