图无法解析为日食错误

Question

I'm having a problem with eclipse where it says graph can not be resolved to a type, its really confusing. Its part of a college program i wrote with the help of a text book.The problem seems to be everywhere i have DistPar, sPath and vertex list. Can anyone help.

public class shortpa {

    public int distance;
    public int parentVert;
    public char label;
    public boolean isInTree;
    public final int MAX_VERTS=20;
    public final int INFINITY=1000000;
    public Vertex vertexList[];
    public int adjMat[][];
    public int nVerts;
    public int nTree;
    public DistPar sPath[];
    public int currentVert;
    public int startToCurrent;


    public static void main(String[] args)
    {
        Graph theGraph = new Graph();//error here saying graph can nt be resolved to a type
        theGraph.addVertex('A');
        theGraph.addVertex('B');
        theGraph.addVertex('C');
        theGraph.addVertex('D');
        theGraph.addVertex('Z');


        theGraph.addEdge(1, 2, 10);//1 repesents A, 2 repesents B....etc and 10 is the weight
        theGraph.addEdge(1, 5, 18);
        theGraph.addEdge(2, 3, 3);
        theGraph.addEdge(2, 5,17);
        theGraph.addEdge(2, 4, 1);
        theGraph.addEdge(3, 4, 1);
        theGraph.addEdge(4, 5, 4);

        System.out.println("Shortest paths");
        theGraph.path();
        System.out.println();

    }
//--------------------------------------------------------------------------    
    public void DistPar(int pv, int d)
    {
        distance = d;
        parentVert=pv;
    }
//--------------------------------------------------------------------------    
    public void Vertex(char lab)
    {
        label = lab;
        isInTree = false;
    }
//--------------------------------------------------------------------------    
    public void Graph()
    {
        vertexList = new Vertex[MAX_VERTS];/////error here saying vertex can not be resolved to a type
        adjMat = new int[MAX_VERTS][MAX_VERTS];
        nVerts=0;
        nTree=0;
        for(int j =0; j<MAX_VERTS; j++)
            for(int k=0; k<MAX_VERTS; k++)
            adjMat[j][k] = INFINITY;
        sPath = new DistPar[MAX_VERTS];//error here saying distpar can not be resolved to a type
    }
//--------------------------------------------------------------------------
    public void addVertex(char lab)
    {
        vertexList[nVerts++] = new Vertex(lab);
    }
//-------------------------------------------------------------------------
    public void addEdge(int start, int end, int weight)////have a look here
    {
        adjMat[start][end]=weight;
    }
//--------------------------------------------------------------------
    public void path()
    {
        int startTree = 0;
        vertexList[startTree].isInTree = true;
        nTree = 1;

        for(int j=0; j<nVerts; j++)
        {
            int tempDist = adjMat[startTree][j];
            sPath[j] = new DistPar(startTree, tempDist);
        }
        while(nTree < nVerts)
        {
            int indexMin = getMin();
            int minDist = sPath[indexMin].distance;

            if(minDist == INFINITY)
            {
                System.out.println("Unreachable vertexs");
                break;
            }
            else
            {
                currentVert=indexMin;
                startToCurrent=sPath[indexMin].distance;
            }
            vertexList[currentVert].isInTree = true;
            nTree++;
            adjust_sPath();
        }
        displayPaths();
        nTree = 0;
        for(int j=0; j<nVerts; j++)
            vertexList[j].isInTree = false;
    }
//---------------------------------------------------------------------------   
    public int getMin()
    {
        int minDist = INFINITY;
        int indexMin = 0;
        for(int j=1; j<nVerts;j++)
        {
            if(!vertexList[j].isInTree && sPath[j].distance < minDist)
            {
                minDist = sPath[j].distance;
                indexMin = j;
            }
        }
        return indexMin;
    }
//------------------------------------------------------------------------------
    public void adjust_sPath()
    {
        int column = 1;
        while(column < nVerts)
        {
            if(vertexList[column].isInTree)
            {
                column++;
                continue;
            }
            int currentToFringe = adjMat[currentVert][column];
            int startToFringe = startToCurrent + currentToFringe;
            int sPathDist = sPath[column].distance;
            if(startToFringe < sPathDist)
            {
                sPath[column].parentVert = currentVert;
                sPath[column].distance = startToFringe;
            }
            column++;
        }
    }
//------------------------------------------------------------------------------
    public void displayPaths()
    {
        for(int j=0; j< nVerts; j++)
        {
            System.out.println(vertexList[j].label+"=");
            if(sPath[j].distance == INFINITY)
                System.out.println("inf");
            else
                System.out.println(sPath[j].distance);
            char parent = vertexList[sPath[j].parentVert].label;
            System.out.println(" (" + parent + ") ");
        }
        System.out.println("");
    }


}

Answer 1

In the line Graph theGraph = new Graph(); it cannot be saying "graph can nt be resolved to a type". It must be saying "Graph cannot be resolved to a type". So, welcome to Java programming; lesson #1: lower case letters vs. upper case letters do really matter .

(Lesson #2: this is not an Eclipse error; it is an error issued by the java compiler. It has absolutely nothing to do with Eclipse; it would be issued in any other IDE as well.)

So, the compiler says that "Graph cannot be resolved to a type" because it does not know what "Graph" is. And that is only natural, because there is no class Graph anywhere to be seen.

Now, further down in your source file I see a public void Graph() , which is attempting to initialize the contents of your shortpa class, so what you probably meant to do instead was to call your class Graph instead of shortpa , and you meant Graph() to be a constructor , not a function returning void.

So, replace class shortpa with class Graph and replace public void Graph() with public Graph() .