FrameLayout IllegalStateException：指定的孩子已经有一个父母

Question

我在从 PreferenceActivity 实例化的对话框中遇到此错误。谁能告诉我怎么了？

public class NumberPickerPreference extends DialogPreference {

    public static final int MAX_VALUE = 24;
    public static final int MIN_VALUE = 2;

    public NumberPicker picker;
    FrameLayout dialogView;
    private int value;
    Context ctx;


    public NumberPickerPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
        ctx = context;
        dialogView = new FrameLayout(ctx);
        picker = new NumberPicker(ctx);
    }

    public NumberPickerPreference(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

    }

    @Override
    protected View onCreateDialogView() {
        FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        layoutParams.gravity = Gravity.CENTER;
        picker.setLayoutParams(layoutParams);
        dialogView.addView(picker); // <- this line has the error

        return dialogView;
    }

    @Override
    public void onDismiss(DialogInterface dialog) {
        super.onDismiss(dialog);
        dialog.dismiss();
    }

    @Override
    protected void onBindDialogView(View view) {
        super.onBindDialogView(view);
        picker.setMinValue(MIN_VALUE);
        picker.setMaxValue(MAX_VALUE);
        picker.setValue(getValue());
    }

    @Override
    protected void onDialogClosed(boolean positiveResult) {
        if (positiveResult) {
            setValue(picker.getValue());
        }
    }

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

    @Override
    protected void onSetInitialValue(boolean restorePersistedValue, Object defaultValue) {
        setValue(restorePersistedValue ? getPersistedInt(MIN_VALUE) : (Integer) defaultValue);
    }

    public void setValue(int value) {
        this.value = value;
        persistInt(this.value);
    }

    public int getValue() {
        return this.value;
    }
}

这是堆栈跟踪

04-26 00:47:30.870  25385-25385/tk.stayhappy.packagetracker E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: tk.stayhappy.packagetracker, PID: 25385
    java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
            at android.view.ViewGroup.addViewInner(ViewGroup.java:3937)
            at android.view.ViewGroup.addView(ViewGroup.java:3787)
            at android.view.ViewGroup.addView(ViewGroup.java:3759)
            at com.android.internal.app.AlertController.setupView(AlertController.java:492)
            at com.android.internal.app.AlertController.installContent(AlertController.java:236)
            at android.app.AlertDialog.onCreate(AlertDialog.java:356)
            at android.app.Dialog.dispatchOnCreate(Dialog.java:373)
            at android.app.Dialog.show(Dialog.java:274)
            at android.preference.DialogPreference.showDialog(DialogPreference.java:294)
            at android.preference.DialogPreference.onClick(DialogPreference.java:274)
            at android.preference.Preference.performClick(Preference.java:983)
            at android.preference.PreferenceScreen.onItemClick(PreferenceScreen.java:214)
            at android.widget.AdapterView.performItemClick(AdapterView.java:305)
            at android.widget.AbsListView.performItemClick(AbsListView.java:1148)
            at android.widget.AbsListView$PerformClick.run(AbsListView.java:3059)
            at android.widget.AbsListView$3.run(AbsListView.java:3866)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5293)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)

我没有更多的想法，因为它可能是错误的。尝试使用 ApplicationContext 更改上下文，在对话框关闭时删除 picker，获取 picker 和 dialogView 的父级并检查 childCount。没运气。还有其他建议吗？

Answer 1

一个视图只能有一个父级。 onCreateDialogView 将返回 dialogView，然后将其添加到视图中（并因此接收父级）。如果onCreateDialogView 被第二次调用，dialogView 将已经有一个父级并且会抛出一个IllegalStateException。相反，在 onCreateDialogView 内部初始化 dialogView 和 picker，这样您每次都可以从新的、无父视图开始。