Merge pull request aimacode#289 from rajatthakur/iss-fix2

Replaced '==' Fixes aimacode#288

Author: ctjoreilly

aima-core/src/main/java/aima/core/environment/tictactoe/TicTacToeState.java

@@ -3,6 +3,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 import aima.core.util.datastructure.XYLocation;
 
@@ -29,7 +30,7 @@ public String getPlayerToMove() {
 	}
 
 	public boolean isEmpty(int col, int row) {
-		return board[getAbsPosition(col, row)] == EMPTY;
+		return Objects.equals(board[getAbsPosition(col, row)], EMPTY);
 	}
 
 	public String getValue(int col, int row) {
@@ -45,16 +46,16 @@ public void mark(XYLocation action) {
 	}
 
 	public void mark(int col, int row) {
-		if (utility == -1 && getValue(col, row) == EMPTY) {
+		if (utility == -1 && Objects.equals(getValue(col, row), EMPTY)) {
 			board[getAbsPosition(col, row)] = playerToMove;
 			analyzeUtility();
-			playerToMove = (playerToMove == X ? O : X);
+			playerToMove = (Objects.equals(playerToMove, X) ? O : X);
 		}
 	}
 
 	private void analyzeUtility() {
 		if (lineThroughBoard()) {
-			utility = (playerToMove == X ? 1 : 0);
+			utility = (Objects.equals(playerToMove, X) ? 1 : 0);
 		} else if (getNumberOfMarkedPositions() == 9) {
 			utility = 0.5;
 		}
@@ -67,7 +68,7 @@ public boolean lineThroughBoard() {
 	private boolean isAnyRowComplete() {
 		for (int row = 0; row < 3; row++) {
 			String val = getValue(0, row);
-			if (val != EMPTY && val == getValue(1, row) && val == getValue(2, row)) {
+			if (!Objects.equals(val, EMPTY) && Objects.equals(val, getValue(1, row)) && Objects.equals(val, getValue(2, row))) {
 				return true;
 			}
 		}
@@ -77,7 +78,7 @@ private boolean isAnyRowComplete() {
 	private boolean isAnyColumnComplete() {
 		for (int col = 0; col < 3; col++) {
 			String val = getValue(col, 0);
-			if (val != EMPTY && val == getValue(col, 1) && val == getValue(col, 2)) {
+			if (!Objects.equals(val, EMPTY) && Objects.equals(val, getValue(col, 1)) && Objects.equals(val, getValue(col, 2))) {
 				return true;
 			}
 		}
@@ -87,11 +88,11 @@ private boolean isAnyColumnComplete() {
 	private boolean isAnyDiagonalComplete() {
 		boolean retVal = false;
 		String val = getValue(0, 0);
-		if (val != EMPTY && val == getValue(1, 1) && val == getValue(2, 2)) {
+		if (!Objects.equals(val, EMPTY) && Objects.equals(val, getValue(1, 1)) && Objects.equals(val, getValue(2, 2))) {
 			return true;
 		}
 		val = getValue(0, 2);
-		if (val != EMPTY && val == getValue(1, 1) && val == getValue(2, 0)) {
+		if (!Objects.equals(val, EMPTY) && Objects.equals(val, getValue(1, 1)) && Objects.equals(val, getValue(2, 0))) {
 			return true;
 		}
 		return retVal;
@@ -138,7 +139,7 @@ public boolean equals(Object anObj) {
 		if (anObj != null && anObj.getClass() == getClass()) {
 			TicTacToeState anotherState = (TicTacToeState) anObj;
 			for (int i = 0; i < 9; i++) {
-				if (board[i] != anotherState.board[i]) {
+				if (!Objects.equals(board[i], anotherState.board[i])) {
 					return false;
 				}
 			}

aima-core/src/main/java/aima/core/environment/vacuum/ModelBasedReflexVacuumAgent.java

@@ -1,6 +1,7 @@
 package aima.core.environment.vacuum;
 
 import java.util.LinkedHashSet;
+import java.util.Objects;
 import java.util.Set;
 
 import aima.core.agent.Action;
@@ -43,7 +44,7 @@ protected DynamicState updateState(DynamicState state,
 				state.setAttribute(ATTRIBUTE_CURRENT_STATE,
 						vep.getLocationState());
 				// Keep track of the state of the different locations
-				if (VacuumEnvironment.LOCATION_A == vep.getAgentLocation()) {
+				if (Objects.equals(VacuumEnvironment.LOCATION_A, vep.getAgentLocation())) {
 					state.setAttribute(ATTRIBUTE_STATE_LOCATION_A,
 							vep.getLocationState());
 				} else {

aima-core/src/main/java/aima/core/environment/vacuum/ReflexVacuumAgent.java

@@ -6,6 +6,8 @@
 import aima.core.agent.impl.AbstractAgent;
 import aima.core.agent.impl.NoOpAction;
 
+import java.util.Objects;
+
 /**
  * Artificial Intelligence A Modern Approach (3rd Edition): Figure 2.8, page 48.<br>
  * <br>
@@ -39,11 +41,11 @@ public Action execute(Percept percept) {
 						.getLocationState()) {
 					return VacuumEnvironment.ACTION_SUCK;
 					// else if location = A then return Right
-				} else if (VacuumEnvironment.LOCATION_A == vep
-						.getAgentLocation()) {
+				} else if (Objects.equals(VacuumEnvironment.LOCATION_A, vep
+                        .getAgentLocation())) {
 					return VacuumEnvironment.ACTION_MOVE_RIGHT;
-				} else if (VacuumEnvironment.LOCATION_B == vep
-						.getAgentLocation()) {
+				} else if (Objects.equals(VacuumEnvironment.LOCATION_B, vep
+						.getAgentLocation())) {
 					// else if location = B then return Left
 					return VacuumEnvironment.ACTION_MOVE_LEFT;
 				}

aima-core/src/main/java/aima/core/nlp/parsing/grammars/Rule.java

@@ -3,6 +3,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * A derivation rule that is contained within a grammar. This rule is probabilistic, in that it 
@@ -65,7 +66,7 @@ public boolean derives( List<String> sentForm ) {
 			return false;
 		}
 		for( int i=0; i < sentForm.size(); i++ ) {
-			if( this.rhs.get(i) != sentForm.get(i)) {
+			if(!Objects.equals(this.rhs.get(i), sentForm.get(i))) {
 				return false;
 			}
 		}