for (; ; )和while (true) 没有区别
看jdk源码的时候,很多地方都是用的for (; ; ),难道跟while (true)有何区别,用javap反汇编了下,实际是一样的
javap -v target.test-classes.com.example.demoweb.DemoWebApplicationTests
源码
public class DemoWebApplicationTests {
public void test1() {
for (; ; ) {
System.out.println(11);
}
}
public void test2() {
while (true) {
System.out.println(11);
}
}
}
反汇编后代码
Warning: Binary file target.test-classes.com.example.demoweb.DemoWebApplicationTests contains com.example.demoweb.DemoWebApplicationTests
Classfile /Users/pigercc/IdeaProjects/demo-web/target/test-classes/com/example/demoweb/DemoWebApplicationTests.class
Last modified Mar 15, 2019; size 632 bytes
MD5 checksum 7c14c6fc2447db0f652238e10b70d796
Compiled from "DemoWebApplicationTests.java"
public class com.example.demoweb.DemoWebApplicationTests
minor version: 0
major version: 52
flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
#1 = Methodref #5.#18 // java/lang/Object."<init>":()V
#2 = Fieldref #19.#20 // java/lang/System.out:Ljava/io/PrintStream;
#3 = Methodref #21.#22 // java/io/PrintStream.println:(I)V
#4 = Class #23 // com/example/demoweb/DemoWebApplicationTests
#5 = Class #24 // java/lang/Object
#6 = Utf8 <init>
#7 = Utf8 ()V
#8 = Utf8 Code
#9 = Utf8 LineNumberTable
#10 = Utf8 LocalVariableTable
#11 = Utf8 this
#12 = Utf8 Lcom/example/demoweb/DemoWebApplicationTests;
#13 = Utf8 test1
#14 = Utf8 StackMapTable
#15 = Utf8 test2
#16 = Utf8 SourceFile
#17 = Utf8 DemoWebApplicationTests.java
#18 = NameAndType #6:#7 // "<init>":()V
#19 = Class #25 // java/lang/System
#20 = NameAndType #26:#27 // out:Ljava/io/PrintStream;
#21 = Class #28 // java/io/PrintStream
#22 = NameAndType #29:#30 // println:(I)V
#23 = Utf8 com/example/demoweb/DemoWebApplicationTests
#24 = Utf8 java/lang/Object
#25 = Utf8 java/lang/System
#26 = Utf8 out
#27 = Utf8 Ljava/io/PrintStream;
#28 = Utf8 java/io/PrintStream
#29 = Utf8 println
#30 = Utf8 (I)V
{
public com.example.demoweb.DemoWebApplicationTests();
descriptor: ()V
flags: ACC_PUBLIC
Code:
stack=1, locals=1, args_size=1
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
LineNumberTable:
line 11: 0
LocalVariableTable:
Start Length Slot Name Signature
0 5 0 this Lcom/example/demoweb/DemoWebApplicationTests;
public void test1();
descriptor: ()V
flags: ACC_PUBLIC
Code:
stack=2, locals=1, args_size=1
0: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
3: bipush 11
5: invokevirtual #3 // Method java/io/PrintStream.println:(I)V
8: goto 0
LineNumberTable:
line 16: 0
LocalVariableTable:
Start Length Slot Name Signature
0 11 0 this Lcom/example/demoweb/DemoWebApplicationTests;
StackMapTable: number_of_entries = 1
frame_type = 0 /* same */
public void test2();
descriptor: ()V
flags: ACC_PUBLIC
Code:
stack=2, locals=1, args_size=1
0: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
3: bipush 11
5: invokevirtual #3 // Method java/io/PrintStream.println:(I)V
8: goto 0
LineNumberTable:
line 22: 0
LocalVariableTable:
Start Length Slot Name Signature
0 11 0 this Lcom/example/demoweb/DemoWebApplicationTests;
StackMapTable: number_of_entries = 1
frame_type = 0 /* same */
}
SourceFile: "DemoWebApplicationTests.java"

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