diff --git a/src/test/java/study/StringCalculator.java b/src/test/java/study/StringCalculator.java
new file mode 100644
index 000000000..ce7d4a2b0
--- /dev/null
+++ b/src/test/java/study/StringCalculator.java
@@ -0,0 +1,73 @@
+package study;
+
+import java.util.Scanner;
+import java.util.StringTokenizer;
+
+public class StringCalculator {
+
+    /** 에러 1 .  계산식이 토큰으로 뽑히지 않음
+     *  해결   .  StringTokenizer stringTokenizer = new StringTokenizer() 3번째 인자에 true 추가
+     *           3번째 인자는 구분자로 토큰을 분리할 때 구분자도 토큰에 포함시킬지 여부 default값은 false
+     * **/
+
+    public static void main(String[] args){
+        String token = "";
+        int amount = 0;
+
+        Scanner sc = new Scanner(System.in);
+
+        System.out.println("계산식 입력 : ");
+
+        String inputData = sc.nextLine();
+        StringTokenizer stringTokenizer = new StringTokenizer(inputData, "+-*/", true);
+
+        try {
+            while (stringTokenizer.hasMoreTokens()){
+
+                token = stringTokenizer.nextToken();
+
+                if (token.equals("+")){
+
+                    token = stringTokenizer.nextToken();
+                    amount += Integer.parseInt(token);
+
+
+                } else if (token.equals("-")) {
+
+                    token = stringTokenizer.nextToken();
+                    amount -= Integer.parseInt(token);
+
+                } else if (token.equals("*")) {
+
+                    token = stringTokenizer.nextToken();
+                    amount *= Integer.parseInt(token);
+
+                } else if (token.equals("/")) {
+
+                    token = stringTokenizer.nextToken();
+                    amount /= Integer.parseInt(token);
+
+                } else {
+                    amount = Integer.parseInt(token);
+                }
+
+            }
+            System.out.println("결과값 : " + amount);
+
+        } catch (NullPointerException e){
+
+        }
+
+
+    }
+
+    public String _StringCalculator() {
+
+        Scanner scanner = new Scanner(System.in);
+
+        String scanInput = scanner.nextLine();
+
+
+        return null;
+    }
+}
diff --git a/src/test/java/study/StringTest.java b/src/test/java/study/StringTest.java
index 43e47d90b..2b4db4c3b 100644
--- a/src/test/java/study/StringTest.java
+++ b/src/test/java/study/StringTest.java
@@ -1,13 +1,99 @@
 package study;
 
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import java.util.HashSet;
+import java.util.Set;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class StringTest {
+    private Set<Integer> numbers;
+
     @Test
     void replace() {
         String actual = "abc".replace("b", "d");
         assertThat(actual).isEqualTo("adc");
     }
+
+    @Test
+    void test1A() {
+        String actual = "1,2";
+        String[] actual1 = actual.split(",");
+
+        assertThat(actual1[0]).contains("1");
+
+    }
+
+    @Test
+    void test1B() {
+        String actual = "1";
+        String[] actual1 = actual.split(",");
+
+        assertThat(actual1).containsExactly("1");
+    }
+
+    @Test
+    void test2() {
+        String actual = "(1,2)";
+        String actual1 = actual.substring(1,4);
+
+        assertThat(actual1).isEqualTo("1,2");
+    }
+
+    @Test
+    void test3() {
+        String actual = "abc";
+        char a = actual.charAt(1);
+
+        assertThat(a).isEqualTo('b');
+    }
+
+    @Test
+    @BeforeEach
+    void test4A() {
+
+        numbers = new HashSet<>();
+        numbers.add(1);
+        numbers.add(1);
+        numbers.add(2);
+        numbers.add(3);
+
+        assertThat(numbers.size()).isEqualTo(3);
+    }
+
+    @ParameterizedTest
+    @ValueSource(ints = {1,2,3})
+    void test4B(int number) {
+
+        numbers = new HashSet<>();
+        numbers.add(1);
+        numbers.add(1);
+        numbers.add(2);
+        numbers.add(3);
+
+//        assertThat(numbers.contains(1)).isTrue();
+//        assertThat(numbers.contains(2)).isTrue();
+//        assertThat(numbers.contains(3)).isTrue();
+
+        assertThat(numbers.contains(number)).isTrue();
+    }
+
+    // TODO
+//    @ParameterizedTest
+//    @CsvSource(value = {"7", "4", "5"})
+//    void test4C(int number) {
+//
+//        numbers = new HashSet<>();
+//        numbers.add(1);
+//        numbers.add(1);
+//        numbers.add(2);
+//        numbers.add(3);
+//
+//        asser
+//    }
 }