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Graph.java
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Graph.java
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package com.baeldung.graph;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
public class Graph {
private Map<Vertex, List<Vertex>> adjVertices;
Graph() {
this.adjVertices = new HashMap<Vertex, List<Vertex>>();
}
void addVertex(String label) {
adjVertices.putIfAbsent(new Vertex(label), new ArrayList<>());
}
void removeVertex(String label) {
Vertex v = new Vertex(label);
adjVertices.values().stream().forEach(e -> e.remove(v));
adjVertices.remove(new Vertex(label));
}
void addEdge(String label1, String label2) {
Vertex v1 = new Vertex(label1);
Vertex v2 = new Vertex(label2);
adjVertices.get(v1).add(v2);
adjVertices.get(v2).add(v1);
}
void removeEdge(String label1, String label2) {
Vertex v1 = new Vertex(label1);
Vertex v2 = new Vertex(label2);
List<Vertex> eV1 = adjVertices.get(v1);
List<Vertex> eV2 = adjVertices.get(v2);
if (eV1 != null)
eV1.remove(v2);
if (eV2 != null)
eV2.remove(v1);
}
List<Vertex> getAdjVertices(String label) {
return adjVertices.get(new Vertex(label));
}
String printGraph() {
StringBuffer sb = new StringBuffer();
for(Vertex v : adjVertices.keySet()) {
sb.append(v);
sb.append(adjVertices.get(v));
}
return sb.toString();
}
class Vertex {
String label;
Vertex(String label) {
this.label = label;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + getOuterType().hashCode();
result = prime * result + ((label == null) ? 0 : label.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Vertex other = (Vertex) obj;
if (!getOuterType().equals(other.getOuterType()))
return false;
if (label == null) {
if (other.label != null)
return false;
} else if (!label.equals(other.label))
return false;
return true;
}
@Override
public String toString() {
return label;
}
private Graph getOuterType() {
return Graph.this;
}
}
}