java递归生成树型结构方式_Java

java递归生成树

1.获取数据

public list<treeclassifyrespvo> gettreeclassifylist(classifypagereqvo reqvo) {
    list<classifydo> classifylist = classifymapper.selectlist(reqvo);
    list<treeclassifyrespvo> childclassifyresp = classifyconvert.instance.convertlist01(classifylist);
    return getclassifytree(childclassifyresp);
}

2.生成树形结构

public list<treeclassifyrespvo> getclassifytree(list<treeclassifyrespvo> childclassifyresp) {
    // 返回的树形数据
    list<treeclassifyrespvo> tree = new arraylist<treeclassifyrespvo>();
    // 第一次遍历
    for (treeclassifyrespvo treeclassify : childclassifyresp) {
        // 找到根节点，这里我的根节点的pid为0
        if (treeclassify.getpid()==0) {
            tree.add(findchild(treeclassify, childclassifyresp));
        }
    }
    return tree;
}

3.查询子节点

private treeclassifyrespvo findchild(treeclassifyrespvo treeclassify, list<treeclassifyrespvo> list) {
    // 定义list用于存储子节点
    list<treeclassifyrespvo> children = new arraylist<treeclassifyrespvo>();
    for (treeclassifyrespvo node : list) {
        // 找到根节点，这里我的根节点的pid为0
        if (node.getpid().equals(treeclassify.getid())) {
            // 调用递归
            children.add(findchild(node, list));
        }
    }
    treeclassify.setchildren(children);
    return treeclassify;
}