項目源碼地址: https://github.com/angcyo/FlowRadioGroup

為了更好的擁有RadioGroup的屬性/方法:
1:新建一個View,繼承RadioGroup

public class FlowRadioGroup extends RadioGroup

流式布局最重要的就是,測量子View 的大小和子View 的布局位置
2:重寫onMeasure和onLayout方法

List<List<View>> mAllViews;//保存所有行的所有View
List<Integer> mLineHeight;//保存每一行的行高

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
    int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
    int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
    int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

    int width = 0, height = 0;
    int lineWidth = 0, lineHeight = 0;
    int childWidth = 0, childHeight = 0;

    mAllViews = new ArrayList<>();
    mLineHeight = new ArrayList<>();

    List<View> lineViews = new ArrayList<>();
    int count = getChildCount();
    for (int i = 0; i < count; i++) {
        View child = getChildAt(i);
        measureChild(child, widthMeasureSpec, heightMeasureSpec);
        LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) child.getLayoutParams();

        childWidth = child.getMeasuredWidth() + params.leftMargin + params.rightMargin;
        childHeight = child.getMeasuredHeight() + params.topMargin + params.bottomMargin;

        if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {
            width = Math.max(width, lineWidth);
            height += lineHeight;
            mLineHeight.add(lineHeight);
            mAllViews.add(lineViews);

            lineWidth = childWidth;
            lineHeight = childHeight;
            lineViews = new ArrayList<>();
        } else {
            lineWidth += childWidth;
            lineHeight = Math.max(childHeight, lineHeight);
        }
        lineViews.add(child);

        if (i == (count - 1)) {
            width = Math.max(width, lineWidth);
            height += lineHeight;
        }
    }
    mLineHeight.add(lineHeight);
    mAllViews.add(lineViews);
    width += getPaddingLeft() + getPaddingRight();
    height += getPaddingTop() + getPaddingBottom();
    setMeasuredDimension(modeWidth == MeasureSpec.AT_MOST ? width : sizeWidth, modeHeight == MeasureSpec.AT_MOST ? height : sizeHeight);
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    int top = getPaddingTop();//開始布局子view的 top距離
    int left = getPaddingLeft();//開始布局子view的 left距離

    int lineNum = mAllViews.size();//行數(shù)
    List<View> lineView;
    int lineHeight;
    for (int i = 0; i < lineNum; i++) {
        lineView = mAllViews.get(i);
        lineHeight = mLineHeight.get(i);

        for (int j = 0; j < lineView.size(); j++) {
            View child = lineView.get(j);
            if (child.getVisibility() == View.GONE) {
                continue;
            }

            LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) child.getLayoutParams();
            int ld = left + params.leftMargin;
            int td = top + params.topMargin;
            int rd = ld + child.getMeasuredWidth();//不需要加上 params.rightMargin,
            int bd = td + child.getMeasuredHeight();//不需要加上 params.bottomMargin, 因為在 onMeasure , 中已經(jīng)加在了 lineHeight 中
            child.layout(ld, td, rd, bd);

            left += child.getMeasuredWidth() + params.leftMargin + params.rightMargin;//因為在 這里添加了;
        }

        left = getPaddingLeft();
        top += lineHeight;
    }
}

到此,基本上布局就可以使用了;
不過還有一個問題,就是布局不具備保存狀態(tài)的能力;
所以需要重寫onSaveInstanceState和onRestoreInstanceState方法;
這里不展示,項目源碼中有,并且也有使用方法;

為了更靈活, 更方便使用;
可以擴張接口;

/**
 * 獲取選中按鈕的索引,從開始, 未選中返回 -1
 */
public int getCheckedRadioButtonIndex() {
    return indexOfChild(findViewById(getCheckedRadioButtonId()));
}

/**
 * 獲取選中按鈕的文本,未選中 返回 空字符串
 */
public String getCheckedRadioButtonText() {
    if (getCheckedRadioButtonId() == -1) {
        return "";
    }
    return ((RadioButton) findViewById(getCheckedRadioButtonId())).getText().toString();
}

更多更好的擴展方法, 大家可以根據(jù)需求定制;

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