BAEL-6078 - Convert an Integer Value into 2-Digit Hex Value in Java (#13682)

core-java-modules/core-java-numbers-6/src/main/java/com/baeldung/integertohex/IntegerToHex.java

@@ -0,0 +1,16 @@
+package com.baeldung.integertohex;
+
+class IntegerToHex {
+    static final String digits = "0123456789ABCDEF";
+    static String integerToHex(int input) {
+        if (input <= 0)
+            return "0";
+        StringBuilder hex = new StringBuilder();
+        while (input > 0) {
+            int digit = input % 16;
+            hex.insert(0, digits.charAt(digit));
+            input = input / 16;
+        }
+        return hex.toString();
+    }
+}

core-java-modules/core-java-numbers-6/src/test/java/com/baeldung/integertohex/IntegerToHexUnitTest.java

@@ -0,0 +1,75 @@
+package com.baeldung.integertohex;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.apache.commons.codec.binary.Hex;
+import org.junit.jupiter.api.Test;
+
+class IntegerToHexUnitTest {
+
+    @Test
+    void givenIntegerValue_whenUseRawMethod_thenWillGetHexValue() {
+        String result = IntegerToHex.integerToHex(1055);
+        assertEquals("41F", result);
+    }
+
+    @Test
+    void givenIntegerNegativeValue_whenUseRawMethod_thenZeroValue() {
+        String result = IntegerToHex.integerToHex(-1055);
+        assertEquals("0", result);
+    }
+
+    @Test
+    void givenIntegerPositiveValue_whenUseStringFormat_thenWillGetHexValue() {
+        String result = String.format("%02x", 255);
+        assertEquals("ff", result);
+    }
+
+    @Test
+    void givenIntegerPositiveValue_whenUseStringFormat_thenWillGetHexValueWithLeftZeros() {
+        String result = String.format("%04x", 255);
+        assertEquals("00ff", result);
+    }
+
+    @Test
+    void givenIntegerPositiveValue_whenUseStringFormat_thenWillGetHexValueWithLeftZerosAndUpperLetter() {
+        String result = String.format("%04X", 255);
+        assertEquals("00FF", result);
+    }
+
+    @Test
+    void givenIntegerValue_whenUseIntegerToHexString_thenWillGetHexValue() {
+        String result = Integer.toHexString(1000);
+        assertEquals("3e8", result);
+    }
+
+    @Test
+    void givenIntegerValue_whenUseLongToHexString_thenWillGetHexValue() {
+        String result = Long.toHexString(255L);
+        assertEquals("ff", result);
+    }
+
+    @Test
+    public void givenNegativeIntegerValue_whenUseIntegerToString_thenWillGetHexValue() {
+        String result = Integer.toString(-1458, 16);
+        assertEquals("-5b2", result);
+    }
+
+    @Test
+    public void givenIntegerValue_whenUseIntegerToString_thenWillGetHexValue() {
+        String result = Integer.toString(1458, 16);
+        assertEquals("5b2", result);
+    }
+
+    @Test
+    public void givenLongValue_whenUseLongToString_thenWillGetHexValue() {
+        String result = Long.toString(158, 16);
+        assertEquals("9e", result);
+    }
+
+    @Test
+    public void givenIntegerValue_whenUseApacheCommons_thenWillGetHexSignedValue() {
+        String result = Hex.encodeHexString(new byte[] { (byte) 254 });
+        assertEquals("fe", result);
+    }
+}