Determine the order of braces is valid using Java

The challenge

Write a function that takes a string of braces, and determines if the order of the braces is valid. It should return true if the string is valid, and false if it’s invalid.

All input strings will be nonempty, and will only consist of parentheses, brackets and curly braces: ()[]{}.

What is considered Valid?

A string of braces is considered valid if all braces are matched with the correct brace.

Examples

"(){}[]" => True "([{}])" => True "(}" => False "[(])" => False "[({})](]" => False
Code language: PHP (php)

The solution in Java code

Option 1:

import java.util.Stack; public class BraceChecker { public boolean isValid(String braces) { Stack<Character> s = new Stack<>(); for (char c : braces.toCharArray()) if (s.size() > 0 && isClosing(s.peek(), c)) s.pop(); else s.push(c); return s.size() == 0; } public boolean isClosing(char x, char c) { return (x == '{' && c == '}') || (x == '(' && c == ')') || (x == '[' && c == ']'); } }
Code language: Java (java)

Option 2:

public class BraceChecker { public boolean isValid(String braces) { String b = braces; System.out.println(braces); for(int i=0;i<braces.length()/2;i++) { b = b.replaceAll("\\(\\)", ""); b = b.replaceAll("\\[\\]", ""); b = b.replaceAll("\\{\\}", ""); if(b.length() == 0) return true; } return false; } }
Code language: Java (java)

Option 3:

public class BraceChecker { public boolean isValid(String s) { int x = s.length(); s = s.replaceAll("\\(\\)|\\[\\]|\\{\\}",""); return s.length() == x ? false : s.length() == 0 || isValid(s); } }
Code language: Java (java)

Option 4:

public class BraceChecker { public boolean isValid(String brackets) { while(brackets.indexOf("{}")!=-1||brackets.indexOf("[]")!=-1||brackets.indexOf("()")!=-1) { brackets = brackets.replace("{}",""); brackets = brackets.replace("[]",""); brackets = brackets.replace("()",""); } return brackets.isEmpty(); } }
Code language: Java (java)

Test cases to validate our solution

import static org.junit.Assert.*; import org.junit.Test; public class BraceCheckerTests { private BraceChecker checker = new BraceChecker(); @Test public void testValid() { assertEquals(true, checker.isValid("()")); assertEquals(true, checker.isValid("[]")); assertEquals(true, checker.isValid("{}")); assertEquals(true, checker.isValid("(){}[]")); assertEquals(true, checker.isValid("([{}])")); assertEquals(true, checker.isValid("({})[({})]")); assertEquals(true, checker.isValid("(({{[[]]}}))")); assertEquals(true, checker.isValid("{}({})[]")); } @Test public void testInvalid() throws Exception { assertEquals(false, checker.isValid("[(])")); assertEquals(false, checker.isValid("(}")); assertEquals(false, checker.isValid("(})")); assertEquals(false, checker.isValid(")(}{][")); assertEquals(false, checker.isValid("())({}}{()][][")); assertEquals(false, checker.isValid("(((({{")); assertEquals(false, checker.isValid("}}]]))}])")); } }
Code language: Java (java)
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