his Java code does not run, it has some errors and it needs a main method, please fix it. import java.io.*; class DecisionTree { /* NESTED CLASS */ private class BinTree { /* FIELDS */ private int nodeID; private String questOrAns = null; private BinTree yesBranch = null; private BinTree noBranch = null; /* CONSTRUCTOR */ public BinTree(int newNodeID, String newQuestAns) { nodeID = newNodeID; questOrAns = newQuestAns; } } /* OTHER FIELDS */ static BufferedReader keyboardInput = new BufferedReader(new InputStreamReader(System.in)); BinTree rootNode = null; /* Default Constructor */ public DecisionTree() { } /* CREATE ROOT NODE */ public void createRoot(int newNodeID, String newQuestAns) { rootNode = new BinTree(newNodeID,newQuestAns); System.out.println("Created root node " + newNodeID); } /* ADD YES NODE */ public void addYesNode(int existingNodeID, int newNodeID, String newQuestAns) { // If no root node do nothing if (rootNode == null) { System.out.println("ERROR: No root node!"); return; } // Search tree if (searchTreeAndAddYesNode(rootNode,existingNodeID,newNodeID,newQuestAns)) { System.out.println("Added node " + newNodeID + " onto \"yes\" branch of node " + existingNodeID); } else System.out.println("Node " + existingNodeID + " not found"); } /* SEARCH TREE AND ADD YES NODE */ private boolean searchTreeAndAddYesNode(BinTree currentNode, int existingNodeID, int newNodeID,
This Java code does not run, it has some errors and it needs a main method, please fix it.
import java.io.*;
class DecisionTree {
/* NESTED CLASS */
private class BinTree {
/* FIELDS */
private int nodeID;
private String questOrAns = null;
private BinTree yesBranch = null;
private BinTree noBranch = null;
/* CONSTRUCTOR */
public BinTree(int newNodeID, String newQuestAns) {
nodeID = newNodeID;
questOrAns = newQuestAns;
}
}
/* OTHER FIELDS */
static BufferedReader keyboardInput = new
BufferedReader(new InputStreamReader(System.in));
BinTree rootNode = null;
/* Default Constructor */
public DecisionTree() {
}
/* CREATE ROOT NODE */
public void createRoot(int newNodeID, String newQuestAns) {
rootNode = new BinTree(newNodeID,newQuestAns);
System.out.println("Created root node " + newNodeID);
}
/* ADD YES NODE */
public void addYesNode(int existingNodeID, int newNodeID, String newQuestAns) {
// If no root node do nothing
if (rootNode == null) {
System.out.println("ERROR: No root node!");
return;
}
// Search tree
if (searchTreeAndAddYesNode(rootNode,existingNodeID,newNodeID,newQuestAns)) {
System.out.println("Added node " + newNodeID +
" onto \"yes\" branch of node " + existingNodeID);
}
else System.out.println("Node " + existingNodeID + " not found");
}
/* SEARCH TREE AND ADD YES NODE */
private boolean searchTreeAndAddYesNode(BinTree currentNode,
int existingNodeID, int newNodeID, String newQuestAns) {
if (currentNode.nodeID == existingNodeID) {
// Found node
if (currentNode.yesBranch == null) currentNode.yesBranch = new
BinTree(newNodeID,newQuestAns);
else {
System.out.println("WARNING: Overwriting previous node " +
"(id = " + currentNode.yesBranch.nodeID +
") linked to yes branch of node " +
existingNodeID);
currentNode.yesBranch = new BinTree(newNodeID,newQuestAns);
}
return(true);
}
else {
// Try yes branch if it exists
if (currentNode.yesBranch != null) {
if (searchTreeAndAddYesNode(currentNode.yesBranch,
existingNodeID,newNodeID,newQuestAns)) {
return(true);
}
else {
// Try no branch if it exists
if (currentNode.noBranch != null) {
return(searchTreeAndAddYesNode(currentNode.noBranch,
existingNodeID,newNodeID,newQuestAns));
}
else return(false); // Not found here
}
}
return(false); // Not found here
}
}
/* ADD NO NODE */
public void addNoNode(int existingNodeID, int newNodeID, String newQuestAns) {
// If no root node do nothing
if (rootNode == null) {
System.out.println("ERROR: No root node!");
return;
}
// Search tree
if (searchTreeAndAddNoNode(rootNode,existingNodeID,newNodeID,newQuestAns)) {
System.out.println("Added node " + newNodeID +
" onto \"no\" branch of node " + existingNodeID);
}
else System.out.println("Node " + existingNodeID + " not found");
}
/* SEARCH TREE AND ADD NO NODE */
private boolean searchTreeAndAddNoNode(BinTree currentNode,
int existingNodeID, int newNodeID, String newQuestAns) {
if (currentNode.nodeID == existingNodeID) {
// Found node
if (currentNode.noBranch == null) currentNode.noBranch = new
BinTree(newNodeID,newQuestAns);
else {
System.out.println("WARNING: Overwriting previous node " +
"(id = " + currentNode.noBranch.nodeID +
") linked to yes branch of node " +
existingNodeID);
currentNode.noBranch = new BinTree(newNodeID,newQuestAns);
}
return(true);
}
else {
// Try yes branch if it exists
if (currentNode.yesBranch != null) {
if (searchTreeAndAddNoNode(currentNode.yesBranch,
existingNodeID,newNodeID,newQuestAns)) {
return(true);
}
else {
// Try no branch if it exists
if (currentNode.noBranch != null) {
return(searchTreeAndAddNoNode(currentNode.noBranch,
existingNodeID,newNodeID,newQuestAns));
}
else return(false); // Not found here
}
}
else return(false); // Not found here
}
}
public void queryBinTree() throws IOException {
queryBinTree(rootNode);
}
private void queryBinTree(BinTree currentNode) throws IOException {
// Test for leaf node (answer) and missing branches
if (currentNode.yesBranch==null) {
if (currentNode.noBranch==null) System.out.println(currentNode.questOrAns);
else System.out.println("Error: Missing \"Yes\" branch at \"" +
currentNode.questOrAns + "\" question");
return;
}
if (currentNode.noBranch==null) {
System.out.println("Error: Missing \"No\" branch at \"" +
currentNode.questOrAns + "\" question");
return;
}
// Question
askQuestion(currentNode);
}
private void askQuestion(BinTree currentNode) throws IOException {
System.out.println(currentNode.questOrAns + " (enter \"Yes\" or \"No\")");
String answer = keyboardInput.readLine();
if (answer.equals("Yes")) queryBinTree(currentNode.yesBranch);
else {
if (answer.equals("No")) queryBinTree(currentNode.noBranch);
else {
System.out.println("ERROR: Must answer \"Yes\" or \"No\"");
askQuestion(currentNode);
}
}
}
/* OUTPUT BIN TREE */
public void outputBinTree() {
outputBinTree("1",rootNode);
}
private void outputBinTree(String tag, BinTree currentNode) {
// Check for empty node
if (currentNode == null) return;
// Output
System.out.println("[" + tag + "] nodeID = " + currentNode.nodeID +
", question/answer = " + currentNode.questOrAns);
// Go down yes branch
outputBinTree(tag + ".1",currentNode.yesBranch);
// Go down no branch
outputBinTree(tag + ".2",currentNode.noBranch);
}
}
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