add hashCode() function to java.lang.StringBuilder

Sources/JavApi/lang/String+Java.swift

@@ -188,6 +188,10 @@ extension String {
     return self
   }
 
+  /// Hashcode of ``String``
+  public func hashCode () -> Int {
+    return self.hashValue
+  }
 }
 
 fileprivate let TRIM_CHARACTER_SET = CharacterSet(charactersIn : "\u{0000}\u{0001}\u{0002}\u{0003}\u{0004}\u{0005}\u{0006}\u{0007}\u{0008}\u{0009}\u{000A}\u{000B}\u{000C}\u{000D}\u{000E}\u{000F}\u{0010}\u{0011}\u{0012}\u{0013}\u{0014}\u{0015}\u{0016}\u{0017}\u{0018}\u{0019}\u{001A}\u{001B}\u{001C}\u{001D}\u{001E}\u{001F}\u{0020}") // different to strip can be readed f.e. here: (https://stackoverflow.com/questions/51266582/difference-between-string-trim-and-strip-methods-in-java-11)

Sources/JavApi/lang/String+Swiftify.swift

@@ -5,6 +5,15 @@
 
 extension String {
 
+  // overwrite Foundation.String hashValue with Java like hashCode
+  var hashValue : Int {
+    var hash = 0
+    for character in self.reversed() {
+      hash = 31 * hash + Int(character.asciiValue!)
+    }
+    return hash
+  }
+
   /// Returns the bytes of String in given encoding
   /// - Returns byte array
   public func getBytes () -> [UInt8] {

Sources/JavApi/lang/StringBuilder+Equalable.swift

@@ -0,0 +1,11 @@
+/*
+ * SPDX-FileCopyrightText: 2024 - Sebastian Ritter <[email protected]>
+ * SPDX-License-Identifier: MIT
+ */
+
+extension StringBuilder : Equatable {
+
+  public static func == (lhs: StringBuilder, rhs: StringBuilder) -> Bool {
+    return lhs === rhs
+  }
+}

Sources/JavApi/lang/StringBuilder+Hashable.swift

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2024 - Sebastian Ritter <[email protected]>
+ * SPDX-License-Identifier: MIT
+ */
+
+import Foundation
+
+extension StringBuilder : Hashable {
+
+  public var hashValue: Int {
+    var hasher = Hasher()
+    hash(into: &hasher)
+    return hasher.finalize()
+  }
+
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(System.identityHashCode(self))
+    hasher.combine(self.content)
+  }
+
+  // the Java method
+  public func hashCode () -> Int {
+    return hashValue
+  }
+}

Sources/JavApi/lang/System.swift

@@ -70,12 +70,12 @@ public struct System {
     }
   }
 
-  /// Return the value from environment variable
-  /// - Returns value of environment variable or nil
-  static public func getenv (_ name : String) -> String? {
-    return ProcessInfo.processInfo.environment[name]
+  /// Return the current time in milliseconds
+  ///
+  /// - Returns: milliseconds as Int64
+  public static func currentTimeMillis () -> Int64 {
+    return Int64(Date().timeIntervalSince1970.advanced(by: 0)*1_000)
   }
-
   /// Exits the application
   /// - Parameters:
   /// - Parameter status return value e.g. for scripting with your application
@@ -85,10 +85,21 @@ public struct System {
     Foundation.exit(Int32(status))
   }
 
-  /// Return the current time in milliseconds
-  ///
-  /// - Returns: milliseconds as Int64
-  public static func currentTimeMillis () -> Int64 {
-    return Int64(Date().timeIntervalSince1970.advanced(by: 0)*1_000)
+  /// Returns a hashCode
+  /// - Note: unsafe
+  public static func identityHashCode (_ x : AnyObject?) -> Int {
+    if let x {
+      return ObjectIdentifier(x).hashValue
+    }
+    else {
+      return 0
+    }
   }
+
+  /// Return the value from environment variable
+  /// - Returns value of environment variable or nil
+  public static func getenv (_ name : String) -> String? {
+    return ProcessInfo.processInfo.environment[name]
+  }
+
 }

Tests/JavApiTests/JavApi_lang_StringBuilder_Tests.swift

@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: 2024 - Sebastian Ritter <[email protected]>
+ * SPDX-License-Identifier: MIT
+ */
+import XCTest
+@testable import JavApi
+
+final class JavApi_lang_StringBuilder_Tests: XCTestCase {
+
+  func testEquals () {
+    let a = StringBuilder("1")
+    let b = StringBuilder("2")
+    let c = StringBuilder("1")
+    XCTAssertFalse(a===b);
+    XCTAssertFalse(a == b) // false
+    XCTAssertTrue(a == a) // true
+    XCTAssertFalse(a===c) // false
+    XCTAssertFalse(a==c) // false
+  }
+
+  func testHashCode () {
+    let a = StringBuilder("1")
+    let b = StringBuilder("2")
+    let c = StringBuilder("1")
+    // call twice with same result
+    XCTAssertEqual(a.hashCode(), a.hashCode())
+    // two objects with different content creates different hashCode
+    XCTAssertNotEqual(a.hashCode(), b.hashCode())
+    // two objects with same content creates different hashCode
+    XCTAssertNotEqual(a.hashCode(), c.hashCode())
+  }
+}