From c76c811b1cb72b71c8c127c9e3da41a731e4adff Mon Sep 17 00:00:00 2001
From: patkorek <patkorek@gmail.com>
Date: Tue, 7 Apr 2020 10:23:15 +0200
Subject: [PATCH] BAEL-2660 few examples to convert String to Int

---
 .../strings/ConvertStringToInt.groovy         | 92 +++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 core-groovy/src/test/groovy/com/baeldung/strings/ConvertStringToInt.groovy

diff --git a/core-groovy/src/test/groovy/com/baeldung/strings/ConvertStringToInt.groovy b/core-groovy/src/test/groovy/com/baeldung/strings/ConvertStringToInt.groovy
new file mode 100644
index 0000000000..40c53965a5
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/strings/ConvertStringToInt.groovy
@@ -0,0 +1,92 @@
+package com.baeldung.strings
+
+import org.junit.Test
+
+import java.text.DecimalFormat
+
+import static org.junit.Assert.assertEquals
+import static org.junit.Assert.assertNull
+
+class ConvertStringToInt {
+
+    @Test
+    void givenString_thenConvertToIntegerUsingAsInteger() {
+        def stringNum = "123"
+        def invalidString = "123a"
+        Integer expectedInteger = 123
+        Integer integerNum = stringNum as Integer
+        def intNum = invalidString?.isInteger() ? invalidString as Integer : null
+
+        assertNull(null, intNum)
+        assertEquals(integerNum, expectedInteger)
+    }
+
+    @Test
+    void givenString_thenConvertToIntUsingAsInt() {
+        def stringNum = "123"
+        int expectedInt = 123
+        int intNum = stringNum as int
+
+        assertEquals(intNum, expectedInt)
+    }
+
+    @Test
+    void givenString_thenConvertToIntegerUsingToInteger() {
+        def stringNum = "123"
+        int expectedInt = 123
+        int intNum = stringNum.toInteger()
+
+        assertEquals(intNum, expectedInt)
+    }
+
+    @Test
+    void givenString_thenConvertToIntegerUsingParseInt() {
+        def stringNum = "123"
+        int expectedInt = 123
+        int intNum = Integer.parseInt(stringNum)
+
+        assertEquals(intNum, expectedInt)
+    }
+
+    @Test
+    void givenString_thenConvertToIntegerUsingValueOf() {
+        def stringNum = "123"
+        int expectedInt = 123
+        int intNum = Integer.valueOf(stringNum)
+
+        assertEquals(intNum, expectedInt)
+    }
+
+    @Test
+    void givenString_thenConvertToIntegerUsingIntValue() {
+        def stringNum = "123"
+        int expectedInt = 123
+        int intNum = new Integer(stringNum).intValue()
+        int secondIntNum = new Integer(stringNum)
+
+        assertEquals(intNum, expectedInt)
+        assertEquals(secondIntNum, expectedInt)
+    }
+
+    @Test
+    void givenString_thenConvertToIntegerUsingDecimalFormat() {
+        def stringNum = "123"
+        int expectedInt = 123
+        DecimalFormat decimalFormat = new DecimalFormat("#")
+        int intNum = decimalFormat.parse(stringNum).intValue()
+
+        assertEquals(intNum, expectedInt)
+    }
+
+    @Test(expected = NumberFormatException.class)
+    void givenInvalidString_whenUsingAs_thenThrowNumberFormatException() {
+        def invalidString = "123a"
+        invalidString as Integer
+    }
+
+    @Test(expected = NullPointerException.class)
+    void givenNullString_whenUsingToInteger_thenThrowNullPointerException() {
+        def invalidString = null
+        invalidString.toInteger()
+    }
+}