Kotlin High Performance Programming

1 .Kotlin High Performance Programming 朱涛 Android Developer, Momo Inc. 

2 .History Java 1.0 in 1996 Kotlin 1.0 in 2016 

3 .Kotlin, a better Java? Safer More Concise More Productive Interoperable Tool-friendly 

4 .What about performance? CPU Memory FPS 

5 .Tools Show Kotlin Bytecode tools Benchmarks https://github.com/Kotlin/kotlin-benchmarks https://developer.android.com/kotlin https://openjdk.java.net/projects/code-tools/jmh/ 

6 .

7 .Show Kotlin Bytecode tools 

8 . Benchmarks apply plugin: 'kotlin-kapt' … dependencies { implementation 'org.openjdk.jmh:jmh-core:1.21' kapt 'org.openjdk.jmh:jmh-generator-annprocess:1.21' } 

9 .StringBuilder 

10 .Java world… 

11 .public static void stringAdd() { String string = ""; for(int i=0;i<10000;i++){ string += "hello"; } } public static void stringBuilder() { StringBuilder builder = new StringBuilder(); for(int i=0;i<10000;i++){ builder.append("hello"); } } 

12 .public static void stringAdd() { String string = ""; for(int i=0;i<10000;i++){ string += "hello"; ① } } public static void stringBuilder() { StringBuilder builder = new StringBuilder(); for(int i=0;i<10000;i++){ builder.append("hello"); ② } } 

13 .public static void stringAdd() { String string = ""; for(int i=0;i<10000;i++){ string += "hello"; ① } } public static void stringBuilder() { StringBuilder builder = new StringBuilder(); for(int i=0;i<10000;i++){ builder.append("hello"); ② } } 

14 .Kotlin world? 

15 .fun stringAdd() { var string = "" for (i in 0..9_999) { string += " kotlin" } } 

16 . SIPUSH 9999 … NEW java/lang/StringBuilder DUP INVOKESPECIAL java/lang/StringBuilder.<init> ()V SWAP INVOKEVIRTUAL java/lang/StringBuilder.append (Ljava/ lang/String;)Ljava/lang/StringBuilder; LDC " kotlin" … GOTO L2 

17 .SIPUSH 9999 … NEW java/lang/StringBuilder ① DUP INVOKESPECIAL java/lang/StringBuilder.<init> ② SWAP INVOKEVIRTUAL java/lang/StringBuilder.append ③ (Ljava/lang/String;)Ljava/lang/StringBuilder; LDC " kotlin" … GOTO L2 

18 .SIPUSH 9999 … NEW java/lang/StringBuilder ① DUP INVOKESPECIAL java/lang/StringBuilder.<init> ② SWAP INVOKEVIRTUAL java/lang/StringBuilder.append ③ (Ljava/lang/String;)Ljava/lang/StringBuilder; LDC " kotlin" … GOTO L2 

19 .fun stringBuilder() { val stringBuilder = StringBuilder() for (i in 0..9_999) { stringBuilder.append(" kotlin") } } 

20 .NEW java/lang/StringBuilder DUP INVOKESPECIAL java/lang/StringBuilder.<init> ()V … SIPUSH 9999 ISTORE 2 … LDC " kotlin" INVOKEVIRTUAL java/lang/StringBuilder.append (Ljava/lang/ String;)Ljava/lang/StringBuilder; … GOTO L2 

21 .NEW java/lang/StringBuilder ① DUP INVOKESPECIAL java/lang/StringBuilder.<init> ② … SIPUSH 9999 ISTORE 2 … LDC " kotlin" INVOKEVIRTUAL java/lang/StringBuilder.append ③ (Ljava/lang/String;)Ljava/lang/StringBuilder; … GOTO L2 

22 .NEW java/lang/StringBuilder ① DUP INVOKESPECIAL java/lang/StringBuilder.<init> ② … SIPUSH 9999 ISTORE 2 … LDC " kotlin" INVOKEVIRTUAL java/lang/StringBuilder.append ③ (Ljava/lang/String;)Ljava/lang/StringBuilder; … GOTO L2 

23 .1. Use StringBuilder in loop 

24 .1. Use StringBuilder in loop — Java coding experience is helpful. 

25 .Primitive 

26 . float Float int Integer double Double byte short Short Byte char Character Primitive 

27 . Float Int float Float int Integer double Double Double byte Byte short Short Byte Short char Char Character Primitive 

28 .Primitive or Wrapper 

29 . Primitive Wrapper int, float… Integer, Float… Object Oriented, Better Performance null instead of 0 Stack Heap