Add @Override to toString

src/Body.java

@@ -110,6 +110,7 @@ public class Body {
      * mass, position (mass center) and current movement. Example:
      * "5.972E24 kg, position: [1.48E11,0.0,0.0] m, movement: [0.0,29290.0,0.0] m/s."
      */
+    @Override
     public String toString() {
         return String.format(
                 "%g kg, position: %s m, movement: %s m/s.",

src/BodyForceTreeMap.java

@@ -101,6 +101,7 @@ public class BodyForceTreeMap {
      * Returns a readable representation of this map, in which key-value pairs are ordered
      * descending according to the mass of the bodies.
      */
+    @Override
     public String toString() {
         return toString(root);
     }

src/Vector3.java

@@ -97,6 +97,7 @@ public class Vector3 {
      * Returns the coordinates of this vector in brackets as a string
      * in the form "[x,y,z]", e.g., "[1.48E11,0.0,0.0]".
      */
+    @Override
     public String toString() {
         return String.format("[%g,%g,%g]", x, y, z);
     }