Longest Substring Without Repeating Character

The Longest Substring Without Repeating Character is the maximum substring or part of a big string where no character is repeated. 

For example in the string WeSome.Org

so the length of the Longest Substring Without Repeating Character is 6.

In the string iamlearningdsalgofromwesome.org

so the length of the Longest Substring Without Repeating Character is 8.

In the string longestuniquesubstring

so the length of the Longest Substring Without Repeating Character is 8.

package org.wesome.dsalgo;

public class LongestUniqueSubString {
    public static int longestUniqueSubString(String str) {
        String window = "";

        int maxLength = -1;
        if (str.isEmpty()) {
            return 0;
        } else if (str.length() == 1) {
            return 1;
        }
        for (char c : str.toLowerCase().toCharArray()) {
            String current = String.valueOf(c);

            // If string already contains the character
            // Then substring after the repeated character
            if (window.contains(current)) {
                window = window.substring(window.indexOf(current) + 1);
            }
            window = window + c;
            maxLength = Math.max(window.length(), maxLength);
        }
        return maxLength;
    }
}

package org.wesome.dsalgo;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class LongestUniqueSubStringTest {
    @Test
    void longestUniqueSubStringTest1() {
        String string = "WeSome.Org";
        Assertions.assertEquals(6, LongestUniqueSubString.longestUniqueSubString(string));
    }

    @Test
    void longestUniqueSubStringTest2() {
        String string = "iAmLearningDsAlgoFromWeSome.Org";
        Assertions.assertEquals(8, LongestUniqueSubString.longestUniqueSubString(string));
    }

    @Test
    void longestUniqueSubStringTest3() {
        String string = "LongestUniqueSubString";
        Assertions.assertEquals(8, LongestUniqueSubString.longestUniqueSubString(string));
    }
}

plugins {
    id 'java'
}

group = 'org.wesome'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = JavaVersion.VERSION_1_8

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter:5.6.2'
}

test {
    useJUnitPlatform()
}