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glmartinglmartin
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Merge pull request eugenp#8218 from yavuztas/pr-BAEL-3408
Source code for BAEL-3408
2 parents 5e8882a + aeb2681 commit 2e1d1ff

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‎data-structures/src/main/java/com/baeldung/printbinarytree/BinaryTreeModel.java‎

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package com.baeldung.printbinarytree;
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public class BinaryTreeModel {
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private Object value;
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private BinaryTreeModel left;
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private BinaryTreeModel right;
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public BinaryTreeModel(Object value) {
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this.value = value;
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}
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public Object getValue() {
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return value;
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}
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public void setValue(Object value) {
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this.value = value;
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}
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public BinaryTreeModel getLeft() {
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return left;
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}
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public void setLeft(BinaryTreeModel left) {
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this.left = left;
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}
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public BinaryTreeModel getRight() {
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return right;
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}
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public void setRight(BinaryTreeModel right) {
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this.right = right;
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}
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}

‎data-structures/src/main/java/com/baeldung/printbinarytree/BinaryTreePrinter.java‎

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package com.baeldung.printbinarytree;
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import java.io.PrintStream;
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public class BinaryTreePrinter {
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private BinaryTreeModel tree;
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public BinaryTreePrinter(BinaryTreeModel tree) {
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this.tree = tree;
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}
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private String traversePreOrder(BinaryTreeModel root) {
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if (root == null) {
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return "";
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}
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StringBuilder sb = new StringBuilder();
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sb.append(root.getValue());
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String pointerRight = "└──";
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String pointerLeft = (root.getRight() != null) ? "├──" : "└──";
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traverseNodes(sb, "", pointerLeft, root.getLeft(), root.getRight() != null);
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traverseNodes(sb, "", pointerRight, root.getRight(), false);
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return sb.toString();
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}
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private void traverseNodes(StringBuilder sb, String padding, String pointer, BinaryTreeModel node,
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boolean hasRightSibling) {
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if (node != null) {
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sb.append("\n");
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sb.append(padding);
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sb.append(pointer);
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sb.append(node.getValue());
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StringBuilder paddingBuilder = new StringBuilder(padding);
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if (hasRightSibling) {
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paddingBuilder.append("│ ");
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} else {
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paddingBuilder.append(" ");
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}
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String paddingForBoth = paddingBuilder.toString();
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String pointerRight = "└──";
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String pointerLeft = (node.getRight() != null) ? "├──" : "└──";
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traverseNodes(sb, paddingForBoth, pointerLeft, node.getLeft(), node.getRight() != null);
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traverseNodes(sb, paddingForBoth, pointerRight, node.getRight(), false);
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}
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}
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public void print(PrintStream os) {
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os.print(traversePreOrder(tree));
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}
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}

‎data-structures/src/test/java/com/baeldung/printbinarytree/PrintingBinaryTreeModelUnitTest.java‎

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package com.baeldung.printbinarytree;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import java.io.ByteArrayOutputStream;
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import java.io.OutputStream;
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import java.io.PrintStream;
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import org.junit.After;
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import org.junit.Before;
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import org.junit.Test;
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import com.baeldung.printbinarytree.BinaryTreeModel;
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import com.baeldung.printbinarytree.BinaryTreePrinter;
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public class PrintingBinaryTreeModelUnitTest {
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private BinaryTreeModel balanced;
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private BinaryTreeModel leftSkewed;
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private BinaryTreeModel rightSkewed;
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private OutputStream output;
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@Before
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public void setup() {
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balanced = createBalancedTree();
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leftSkewed = createLeftUnbalancedTree();
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rightSkewed = createRightUnbalancedTree();
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output = new ByteArrayOutputStream();
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System.setOut(new PrintStream(output));
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}
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@After
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public void tearDown() {
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System.setOut(System.out);
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}
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private BinaryTreeModel createBalancedTree() {
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BinaryTreeModel root = new BinaryTreeModel("root");
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BinaryTreeModel node1 = new BinaryTreeModel("node1");
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BinaryTreeModel node2 = new BinaryTreeModel("node2");
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root.setLeft(node1);
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root.setRight(node2);
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BinaryTreeModel node3 = new BinaryTreeModel("node3");
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BinaryTreeModel node4 = new BinaryTreeModel("node4");
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node1.setLeft(node3);
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node1.setRight(node4);
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node2.setLeft(new BinaryTreeModel("node5"));
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node2.setRight(new BinaryTreeModel("node6"));
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BinaryTreeModel node7 = new BinaryTreeModel("node7");
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node3.setLeft(node7);
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node7.setLeft(new BinaryTreeModel("node8"));
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node7.setRight(new BinaryTreeModel("node9"));
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return root;
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}
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private BinaryTreeModel createLeftUnbalancedTree() {
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BinaryTreeModel root = new BinaryTreeModel("root");
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BinaryTreeModel node1 = new BinaryTreeModel("node1");
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root.setLeft(node1);
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root.setRight(new BinaryTreeModel("node2"));
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BinaryTreeModel node3 = new BinaryTreeModel("node3");
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node1.setLeft(node3);
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BinaryTreeModel node4 = new BinaryTreeModel("node4");
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node3.setLeft(node4);
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BinaryTreeModel node5 = new BinaryTreeModel("node5");
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node4.setLeft(node5);
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BinaryTreeModel node6 = new BinaryTreeModel("node6");
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node5.setLeft(node6);
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BinaryTreeModel node7 = new BinaryTreeModel("node7");
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node6.setLeft(node7);
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node7.setLeft(new BinaryTreeModel("node8"));
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return root;
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}
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private BinaryTreeModel createRightUnbalancedTree() {
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BinaryTreeModel root = new BinaryTreeModel("root");
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BinaryTreeModel node2 = new BinaryTreeModel("node2");
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root.setLeft(new BinaryTreeModel("node1"));
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root.setRight(node2);
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BinaryTreeModel node3 = new BinaryTreeModel("node3");
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node2.setRight(node3);
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BinaryTreeModel node4 = new BinaryTreeModel("node4");
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node3.setRight(node4);
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BinaryTreeModel node5 = new BinaryTreeModel("node5");
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node4.setRight(node5);
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BinaryTreeModel node6 = new BinaryTreeModel("node6");
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node5.setRight(node6);
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BinaryTreeModel node7 = new BinaryTreeModel("node7");
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node6.setRight(node7);
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node7.setRight(new BinaryTreeModel("node8"));
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return root;
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}
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@Test
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public void givenBinaryTreeModelBalanced_whenPrintWithBinaryTreePrinter_thenProduceCorrectOutput() {
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StringBuilder expected = new StringBuilder();
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expected.append("root").append("\n");
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expected.append("├──node1").append("\n");
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expected.append("│ ├──node3").append("\n");
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expected.append("│ │ └──node7").append("\n");
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expected.append("│ │ ├──node8").append("\n");
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expected.append("│ │ └──node9").append("\n");
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expected.append("│ └──node4").append("\n");
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expected.append("└──node2").append("\n");
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expected.append(" ├──node5").append("\n");
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expected.append(" └──node6");
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new BinaryTreePrinter(balanced).print(System.out);
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assertEquals(expected.toString(), output.toString());
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}
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@Test
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public void givenBinaryTreeModelLeftUnbalanced_whenPrintWithBinaryTreePrinter_thenProduceCorrectOutput() {
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StringBuilder expected = new StringBuilder();
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expected.append("root").append("\n");
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expected.append("├──node1").append("\n");
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expected.append("│ └──node3").append("\n");
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expected.append("│ └──node4").append("\n");
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expected.append("│ └──node5").append("\n");
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expected.append("│ └──node6").append("\n");
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expected.append("│ └──node7").append("\n");
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expected.append("│ └──node8").append("\n");
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expected.append("└──node2");
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new BinaryTreePrinter(leftSkewed).print(System.out);
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assertEquals(expected.toString(), output.toString());
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}
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@Test
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public void givenBinaryTreeModelRightUnbalanced_whenPrintWithBinaryTreePrinter_thenProduceCorrectOutput() {
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StringBuilder expected = new StringBuilder();
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expected.append("root").append("\n");
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expected.append("├──node1").append("\n");
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expected.append("└──node2").append("\n");
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expected.append(" └──node3").append("\n");
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expected.append(" └──node4").append("\n");
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expected.append(" └──node5").append("\n");
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expected.append(" └──node6").append("\n");
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expected.append(" └──node7").append("\n");
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expected.append(" └──node8");
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new BinaryTreePrinter(rightSkewed).print(System.out);
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assertEquals(expected.toString(), output.toString());
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}
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}

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