​面试官疯了：While(true)和For(;;)哪个性能好？_每日快播

有人愿意用While(true)因为他更清晰的看出来这里是个无限循环。有人愿意用For(;;)，因为有些IDE对于While(true)会给出警告。至于你，爱用啥用啥！

【资料图】

while(true)和for(;;)都是做无限循环的代码，他俩有啥区别呢？

我承认这个问题有点无聊，并且工作中也不会有人刻意的去考虑他们之间的性能差异，也不太会有人在做这个选择之间纠结。

但是，最近竟然有很多面试官开始问这个问题，所以，那就索性理性分析一波。

准备2段代码：

public class HollisTest {    public static void main(String[] args) {        for(;;){            System.out.println("this is hollis testing....");        }    }}

public class HollisTest {        public static void main(String[] args) {        while (true){            System.out.println("this is hollis testing....");        }    }}

关于这个问题，网上有很多讨论，说那么多没用，直接反编译，看看字节码有啥区别就行了。

分别将他们编译成class文件：

javac HollisTest.java

然后再通过javap对class文件进行反编译，然后我们就会发现，两个文件内容，一模一样！！！

Classfile /Users/hollis/workspace/chaojue/HLab/src/main/java/HollisTest.class  Last modified 2023-6-18; size 463 bytes  MD5 checksum 38eddb7d25748625d7c9aa377b6f66d3  Compiled from "HollisTest.java"public class HollisTest  minor version: 0  major version: 52  flags: ACC_PUBLIC, ACC_SUPERConstant pool:   #1 = Methodref          #6.#16         // java/lang/Object."":()V   #2 = Fieldref           #17.#18        // java/lang/System.out:Ljava/io/PrintStream;   #3 = String             #19            // this is hollis testing....   #4 = Methodref          #20.#21        // java/io/PrintStream.println:(Ljava/lang/String;)V   #5 = Class              #22            // HollisTest   #6 = Class              #23            // java/lang/Object   #7 = Utf8                  #8 = Utf8               ()V   #9 = Utf8               Code  #10 = Utf8               LineNumberTable  #11 = Utf8               main  #12 = Utf8               ([Ljava/lang/String;)V  #13 = Utf8               StackMapTable  #14 = Utf8               SourceFile  #15 = Utf8               HollisTest.java  #16 = NameAndType        #7:#8          // "":()V  #17 = Class              #24            // java/lang/System  #18 = NameAndType        #25:#26        // out:Ljava/io/PrintStream;  #19 = Utf8               this is hollis testing....  #20 = Class              #27            // java/io/PrintStream  #21 = NameAndType        #28:#29        // println:(Ljava/lang/String;)V  #22 = Utf8               HollisTest  #23 = Utf8               java/lang/Object  #24 = Utf8               java/lang/System  #25 = Utf8               out  #26 = Utf8               Ljava/io/PrintStream;  #27 = Utf8               java/io/PrintStream  #28 = Utf8               println  #29 = Utf8               (Ljava/lang/String;)V{  public HollisTest();    descriptor: ()V    flags: ACC_PUBLIC    Code:      stack=1, locals=1, args_size=1         0: aload_0         1: invokespecial #1                  // Method java/lang/Object."":()V         4: return      LineNumberTable:        line 1: 0  public static void main(java.lang.String[]);    descriptor: ([Ljava/lang/String;)V    flags: ACC_PUBLIC, ACC_STATIC    Code:      stack=2, locals=1, args_size=1         0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;         3: ldc           #3                  // String this is hollis testing....         5: invokevirtual #4                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V         8: goto          0      LineNumberTable:        line 5: 0      StackMapTable: number_of_entries = 1        frame_type = 0 /* same */}SourceFile: "HollisTest.java"

可以看到，两个用法，其实都是通过goto来干的，所以，这两者其实是没啥区别的。用哪个都行

有人愿意用while(true)因为他更清晰的看出来这里是个无限循环。有人愿意用for(;;)，因为有些IDE对于while(true)会给出警告。至于你，爱用啥用啥！

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