Add chapt. 5

snippet/ch5/EqualsMain.java

+class Person {
+  protected int id;
+  protected String name;
+  public Person(int id, String name) {
+    this.id = id; this.name = name;
+  }
+  @Override public String toString() {
+    return "Person(" + this.id + ", " + this.name + ")";
+  }
+  @Override public boolean equals(Object o) {
+    if(this == o) return true;
+    if(o == null || !(o instanceof Person)) {
+      return false; }
+    Person p = (Person)o;
+    return p.id == this.id && p.name.equals(this.name);
+  } 
+}
+
+class Patient extends Person {
+    public Patient(int id, String name) {
+      super(id, name);
+    }
+    @Override public String toString() {
+      return "Patient(" + this.id + ", " + this.name + ")";
+    }
+    @Override public boolean equals(Object o) {
+      if(this == o) return true;
+      if(o == null || !(o instanceof Patient)) {
+        return false; }
+      Patient p = (Patient)o;
+      return p.id == this.id && p.name.equals(this.name);
+    } 
+  }
+
+public class EqualsMain {
+    public static void main(String[] args) {
+
+
+    }
+}
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