Java Interview Questions and Sample Solutions (Sorting Units, Coding Challenges, and Common Topics)

1. Personality Test

Select positive options; note that the personality test may also affect candidate selection.

2. Programming Test

Problem: Given an array with size units such as 20M, 1T, 300G (where 1T=1000G, 1G=1000M), output the values sorted from smallest to largest.

Example Input: 20M<br/>1T<br/>300G Example Output: 20M<br/>300G<br/>1T Solution (Java):

package Huawei;<br/><br/>import java.util.Scanner;<br/><br/>/**<br/> * Created by xuzhenyu on 2020/1/5.<br/> */<br/>public class Test {<br/>    public static void main(String[] args) {<br/>        Scanner scanner = new Scanner(System.in);<br/>        int n = scanner.nextInt();<br/>        String[] strings = new String[n];<br/>        for (int i = 0; i < n; i++) {<br/>            strings[i] = scanner.next();<br/>        }<br/>        String[] resultStrs = sort(strings);<br/>        for (int i = 0; i < resultStrs.length; i++) {<br/>            System.out.println(resultStrs[i]);<br/>        }<br/>    }<br/>    private static String[] sort(String[] strs) {<br/>        for (int i = 0; i < strs.length - 1; i++) {<br/>            for (int j = 0; j < strs.length - i - 1; j++) {<br/>                // M G T<br/>                if (compare(strs[j], strs[j + 1])) {<br/>                    String tem = strs[j];<br/>                    strs[j] = strs[j + 1];<br/>                    strs[j + 1] = tem;<br/>                }<br/>            }<br/>        }<br/>        return strs;<br/>    }<br/>    private static boolean compare(String str1, String str2) {<br/>        int str1M = turnString(str1);<br/>        int str2M = turnString(str2);<br/>        return str1M > str2M;<br/>    }<br/>    private static int turnString(String str) {<br/>        if ("M".equals(String.valueOf(str.charAt(str.length() - 1)))) {<br/>            return Integer.parseInt(str.substring(0, str.length() - 1));<br/>        } else if ("G".equals(String.valueOf(str.charAt(str.length() - 1)))) {<br/>            return Integer.parseInt(str.substring(0, str.length() - 1)) * 1000;<br/>        } else if ("T".equals(String.valueOf(str.charAt(str.length() - 1)))) {<br/>            return Integer.parseInt(str.substring(0, str.length() - 1)) * 1000000;<br/>        }<br/>        return 0;<br/>    }<br/>}<br/>

3. Additional Interview Questions

3.1 Two Coding Problems

(1) Given an array where only one element appears once and all others appear twice, output the unique element. (Reference to previous interview collections.)

Example Input: {2,2,1,1,4,4,7}

Output: 7

(2) See the attached image for the second coding problem.

3.2 Interview Topics

(1) Describe common factory design patterns.

(2) Steps to locate a Full GC performance issue.

(3) MySQL database optimization techniques.

(4) Zookeeper leader election mechanism.

These constitute the core interview segment.

Additional Resources

Links to extensive interview question archives (e.g., 001–180 issues, HashMap interview Q&A, Spring Cloud questions, SQL optimization, Redis topics, etc.) are provided for further study.