如何在 Java 的广度优先搜索中将字符串顶点转换为 Integer 顶点

Question

I'm trying to get data from a txt file and create a graph. But I can't do this because vertex1 and vertex2 are String values.

for example

Vertex1 - Vertex2 - Edges

John Lisa 4...

As I understand it, in order to write this Breadth First Search method, I need to save the String values in a hash table but I can't because I need integer values. How can I do it?

Answer 1

Meant is mapping names to a counter.

private final Map<String, Integer> vertexIdsByName = new HashMap<>();

public int getVertexId(String name) {
    return vertexIdsByName.computeIfAbsent(name,
            nm -> vertexIdsByName.size() + 1);
}

The above translates vertex names to an integer ID, 1, 2, 3, ...

If the asked vertex name already is present, its ID is returned, otherwise a new ID, the number of elements in the HashMap + 1 is stored as the new ID and returned.