RelativeLayout addRule踩坑之旅-白红宇

Android设置一些属性时，可以使用|来表示同时设置的功能。比如Gravity

private int mGravity = Gravity.START | Gravity.TOP;复制代码

最近项目中代码改动，将xml的view，改成在java代码中添加。写成了下面代码

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);params.addRule(ALIGN_PARENT_BOTTOM | ALIGN_PARENT_RIGHT);复制代码

导致布局出错。查看源代码

/**         * Adds a layout rule to be interpreted by the RelativeLayout.         *          * Use this for verbs that refer to a sibling (ex.         * {@link #ALIGN_RIGHT}) or take a boolean value (ex.         * {@link #CENTER_IN_PARENT}).         * 
         * If the rule is relative to the layout direction (ex.         * {@link #START_OF}), then the layout direction must be resolved using         * {@link #resolveLayoutDirection(int)} before calling         * {@link #getRule(int)} with an absolute rule (ex. {@link #LEFT_OF}.         *         * @param verb a layout verb, such as {@link #ALIGN_RIGHT}         * @param subject the ID of another view to use as an anchor, or a         *                boolean value (represented as {@link #TRUE} for true         *                or 0 for false)         * @see #addRule(int)         * @see #removeRule(int)         * @see #getRule(int)         */        public void addRule(int verb, int subject) {            // If we're removing a relative rule, we'll need to force layout            // resolution the next time it's requested.            if (!mNeedsLayoutResolution && isRelativeRule(verb)                    && mInitialRules[verb] != 0 && subject == 0) {                mNeedsLayoutResolution = true;            }            mRules[verb] = subject;            mInitialRules[verb] = subject;            mRulesChanged = true;        }复制代码

Android使用的是数组，对Rule进行的缓存，即规则是一一对应的。

/**     * Rule that aligns a child's right edge with another child's left edge.     */    public static final int LEFT_OF                  = 0;    /**     * Rule that aligns a child's left edge with another child's right edge.     */    public static final int RIGHT_OF                 = 1;    /**     * Rule that aligns a child's bottom edge with another child's top edge.     */    public static final int ABOVE                    = 2;    /**     * Rule that aligns a child's top edge with another child's bottom edge.     */    public static final int BELOW                    = 3;    /**     * Rule that aligns a child's baseline with another child's baseline.     */    public static final int ALIGN_BASELINE           = 4;    /**     * Rule that aligns a child's left edge with another child's left edge.     */    public static final int ALIGN_LEFT               = 5;    /**     * Rule that aligns a child's top edge with another child's top edge.     */    public static final int ALIGN_TOP                = 6;    /**     * Rule that aligns a child's right edge with another child's right edge.     */    public static final int ALIGN_RIGHT              = 7;    /**     * Rule that aligns a child's bottom edge with another child's bottom edge.     */    public static final int ALIGN_BOTTOM             = 8;    /**     * Rule that aligns the child's left edge with its RelativeLayout     * parent's left edge.     */    public static final int ALIGN_PARENT_LEFT        = 9;    /**     * Rule that aligns the child's top edge with its RelativeLayout     * parent's top edge.     */    public static final int ALIGN_PARENT_TOP         = 10;    /**     * Rule that aligns the child's right edge with its RelativeLayout     * parent's right edge.     */    public static final int ALIGN_PARENT_RIGHT       = 11;    /**     * Rule that aligns the child's bottom edge with its RelativeLayout     * parent's bottom edge.     */    public static final int ALIGN_PARENT_BOTTOM      = 12;    /**     * Rule that centers the child with respect to the bounds of its     * RelativeLayout parent.     */    public static final int CENTER_IN_PARENT         = 13;    /**     * Rule that centers the child horizontally with respect to the     * bounds of its RelativeLayout parent.     */    public static final int CENTER_HORIZONTAL        = 14;    /**     * Rule that centers the child vertically with respect to the     * bounds of its RelativeLayout parent.     */    public static final int CENTER_VERTICAL          = 15;    /**     * Rule that aligns a child's end edge with another child's start edge.     */    public static final int START_OF                 = 16;    /**     * Rule that aligns a child's start edge with another child's end edge.     */    public static final int END_OF                   = 17;    /**     * Rule that aligns a child's start edge with another child's start edge.     */    public static final int ALIGN_START              = 18;    /**     * Rule that aligns a child's end edge with another child's end edge.     */    public static final int ALIGN_END                = 19;    /**     * Rule that aligns the child's start edge with its RelativeLayout     * parent's start edge.     */    public static final int ALIGN_PARENT_START       = 20;    /**     * Rule that aligns the child's end edge with its RelativeLayout     * parent's end edge.     */    public static final int ALIGN_PARENT_END         = 21;复制代码

每个规则对应数组的下标，所以不能进行位运算。

记录一下，防止以后再惯性思维导致出错。

需要分别调用addRule添加

RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(                ViewGroup.LayoutParams.WRAP_CONTENT,                ViewGroup.LayoutParams.WRAP_CONTENT);lp.addRule(ALIGN_PARENT_BOTTOM);lp.addRule(ALIGN_PARENT_RIGHT);复制代码