用java建立无向图，然后进行深度和广度遍历，下列的代码怎么改

Question

import java.util.LinkedList;
import java.util.Queue;
class MatrixUDG {
static int vlen;
int elen;
int[][] mMatrix;
char[] mVexs;
private int number = 7;
private boolean[] flag;
int[][] edges;
MatrixUDG(char[] vexs, char[][] edges) {
// 初始化"顶点数"和"边数"
int vlen = vexs.length;
int elen = edges.length;
// 初始化"顶点"
mVexs = new char[vlen];
for (int i = 0; i < mVexs.length; i++)
mVexs[i] = vexs[i];
// 初始化"边"
mMatrix = new int[vlen][vlen];
this.edges = new int[vlen][vlen];
for (int i = 0; i < elen; i++) {
// 读取边的起始顶点和结束顶点
int p1 = getPosition(edges[i][0]);
int p2 = getPosition(edges[i][1]);
// mMatrix[p1][p2] = 1;
// mMatrix[p2][p1] = 1;

        this.edges[p1][p2] = 1;
        this.edges[p1][p2] = 1;
    }

    flag = new boolean[vlen];

}

/*
 * 返回ch位置
 */
int getPosition(char ch) {
    for (int i = 0; i < mVexs.length; i++)
        if (mVexs[i] == ch)
            return i;
    return -1;
}

public void print() {
    System.out.printf("Martix Graph:\n");
    for (int i = 0; i < mVexs.length; i++) {
        for (int j = 0; j < mVexs.length; j++)
            System.out.printf("%d ", mMatrix[i][j]);
        System.out.printf("\n");
    }
}

void DFSTraverse() {
    flag = new boolean[number];
    for (int i = 0; i < number; i++) {
        if (flag[i] == false) {// 当前顶点没有被访问
            DFS(i);
        }
    }
}

void DFS(int i) {
    flag[i] = true;// 第i个顶点被访问
    System.out.print(mVexs[i] + " ");
    for (int j = 0; j < number; j++) {
        if (flag[j] == false && edges[i][j] == 1) {
            DFS(j);
        }
    }
}

void BFSTraverse() {
    flag = new boolean[number];
    Queue<Integer> queue = new LinkedList<Integer>();
    for (int i = 0; i < number; i++) {
        if (flag[i] == false) {
            flag[i] = true;
            System.out.print(mVexs[i] + " ");
            queue.add(i);
            while (!queue.isEmpty()) {
                int j = queue.poll();
                for (int k = 0; k < number; k++) {
                    if (edges[j][k] == 1 && flag[k] == false) {
                        flag[k] = true;
                        System.out.print(mVexs[k] + " ");
                        queue.add(k);
                    }
                }
            }
        }
    }
}

}
class Test {
public static void main(String[] args) {
char[] vexs = { 'A', 'B', 'C', 'D', 'E', 'F', 'G' };
char[][] edges = new char[][] { { 'A', 'C' }, { 'A', 'D' },
{ 'A', 'F' }, { 'B', 'C' }, { 'C', 'D' }, { 'E', 'G' },
{ 'F', 'G' } };
MatrixUDG t = new MatrixUDG(vexs, edges);
t.print(); // 打印图
System.out.println("图的深度遍历操作:" + " ");
t.DFSTraverse();
System.out.println();
System.out.println("图的广度遍历操作:"+" ");
t.BFSTraverse();
}
}

Answer 1

单步调试下，看看变量是否为null