What does “p” in “javap” stand for?

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长情又很酷
长情又很酷 2021-01-31 02:46

What does \"p\" in \"javap\" stand for? (The \"c\" in \"javac\" stands for compiler)

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  • 2021-01-31 03:06

    Official Documentation(Java 13).

    Besides what has been answered, let's introspect javap:

    As you can see, from the options description, p in javap most probably stands for print(as the description consists MOSTLY of print this, print that, show this, show that...).

    javap -help
    Usage: javap <options> <classes>
    where possible options include:
      -help  --help  -?        Print this usage message
      -version                 Version information
      -v  -verbose             Print additional information
      -l                       Print line number and local variable tables
      -public                  Show only public classes and members
      -protected               Show protected/public classes and members
      -package                 Show package/protected/public classes
                               and members (default)
      -p  -private             Show all classes and members
      -c                       Disassemble the code
      -s                       Print internal type signatures
      -sysinfo                 Show system info (path, size, date, MD5 hash)
                               of class being processed
      -constants               Show final constants
      -classpath <path>        Specify where to find user class files
      -cp <path>               Specify where to find user class files
      -bootclasspath <path>    Override location of bootstrap class files
    

    Example usage and output(on stdout):

    public class CheckoutJavaP{ 
        private static int i = 1;
        protected static String s = "string";
        public static void main(String[] args){
            InnerClass iC = new InnerClass();
            iC.show();
            System.out.println(s + i);
        }
    }
    
    class InnerClass{
        protected int count;
        public InnerClass(){ System.out.println("In InnerClass Constructor");}
        public void show(){ System.out.println("In InnerClass.show()");}
        public int getCount(){ return this.count;}
    }
    

    (Note: As per its definition, the output below has no mention of InnerClass, only the class it is introspecting and no mention of the private property):

    The javap command disassembles one or more class files. The output depends on the options used. When no options are used, then the javap command prints the package, protected and public fields, and methods of the classes passed to it. The javap command prints its output to stdout.

     javap CheckoutJavaP.class
        Compiled from "CheckoutJavaP.java"
        public class CheckoutJavaP {
          protected static java.lang.String s;
          public CheckoutJavaP();
          public static void main(java.lang.String[]);
          static {};
        }
    

    The verbose javap is(if you are interested):

    javap -v CheckoutJavaP.class
    Classfile /C:/Users/jumping_monkey/CheckoutJavaP.class
      Last modified 9 Feb, 2020; size 822 bytes
      MD5 checksum fb7f219851715ef4489ebf7a47800d47
      Compiled from "CheckoutJavaP.java"
    public class CheckoutJavaP
      minor version: 0
      major version: 52
      flags: ACC_PUBLIC, ACC_SUPER
    Constant pool:
       #1 = Methodref          #16.#30        // java/lang/Object."<init>":()V
       #2 = Class              #31            // InnerClass
       #3 = Methodref          #2.#30         // InnerClass."<init>":()V
       #4 = Methodref          #2.#32         // InnerClass.show:()V
       #5 = Fieldref           #33.#34        // java/lang/System.out:Ljava/io/PrintStream;
       #6 = Class              #35            // java/lang/StringBuilder
       #7 = Methodref          #6.#30         // java/lang/StringBuilder."<init>":()V
       #8 = Fieldref           #15.#36        // CheckoutJavaP.s:Ljava/lang/String;
       #9 = Methodref          #6.#37         // java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      #10 = Fieldref           #15.#38        // CheckoutJavaP.i:I
      #11 = Methodref          #6.#39         // java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
      #12 = Methodref          #6.#40         // java/lang/StringBuilder.toString:()Ljava/lang/String;
      #13 = Methodref          #41.#42        // java/io/PrintStream.println:(Ljava/lang/String;)V
      #14 = String             #43            // string
      #15 = Class              #44            // CheckoutJavaP
      #16 = Class              #45            // java/lang/Object
      #17 = Utf8               i
      #18 = Utf8               I
      #19 = Utf8               s
      #20 = Utf8               Ljava/lang/String;
      #21 = Utf8               <init>
      #22 = Utf8               ()V
      #23 = Utf8               Code
      #24 = Utf8               LineNumberTable
      #25 = Utf8               main
      #26 = Utf8               ([Ljava/lang/String;)V
      #27 = Utf8               <clinit>
      #28 = Utf8               SourceFile
      #29 = Utf8               CheckoutJavaP.java
      #30 = NameAndType        #21:#22        // "<init>":()V
      #31 = Utf8               InnerClass
      #32 = NameAndType        #46:#22        // show:()V
      #33 = Class              #47            // java/lang/System
      #34 = NameAndType        #48:#49        // out:Ljava/io/PrintStream;
      #35 = Utf8               java/lang/StringBuilder
      #36 = NameAndType        #19:#20        // s:Ljava/lang/String;
      #37 = NameAndType        #50:#51        // append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      #38 = NameAndType        #17:#18        // i:I
      #39 = NameAndType        #50:#52        // append:(I)Ljava/lang/StringBuilder;
      #40 = NameAndType        #53:#54        // toString:()Ljava/lang/String;
      #41 = Class              #55            // java/io/PrintStream
      #42 = NameAndType        #56:#57        // println:(Ljava/lang/String;)V
      #43 = Utf8               string
      #44 = Utf8               CheckoutJavaP
      #45 = Utf8               java/lang/Object
      #46 = Utf8               show
      #47 = Utf8               java/lang/System
      #48 = Utf8               out
      #49 = Utf8               Ljava/io/PrintStream;
      #50 = Utf8               append
      #51 = Utf8               (Ljava/lang/String;)Ljava/lang/StringBuilder;
      #52 = Utf8               (I)Ljava/lang/StringBuilder;
      #53 = Utf8               toString
      #54 = Utf8               ()Ljava/lang/String;
      #55 = Utf8               java/io/PrintStream
      #56 = Utf8               println
      #57 = Utf8               (Ljava/lang/String;)V
    {
      protected static java.lang.String s;
        descriptor: Ljava/lang/String;
        flags: ACC_PROTECTED, ACC_STATIC
    
      public CheckoutJavaP();
        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 1: 0
    
      public static void main(java.lang.String[]);
        descriptor: ([Ljava/lang/String;)V
        flags: ACC_PUBLIC, ACC_STATIC
        Code:
          stack=3, locals=2, args_size=1
             0: new           #2                  // class InnerClass
             3: dup
             4: invokespecial #3                  // Method InnerClass."<init>":()V
             7: astore_1
             8: aload_1
             9: invokevirtual #4                  // Method InnerClass.show:()V
            12: getstatic     #5                  // Field java/lang/System.out:Ljava/io/PrintStream;
            15: new           #6                  // class java/lang/StringBuilder
            18: dup
            19: invokespecial #7                  // Method java/lang/StringBuilder."<init>":()V
            22: getstatic     #8                  // Field s:Ljava/lang/String;
            25: invokevirtual #9                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            28: getstatic     #10                 // Field i:I
            31: invokevirtual #11                 // Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
            34: invokevirtual #12                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
            37: invokevirtual #13                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
            40: return
          LineNumberTable:
            line 5: 0
            line 6: 8
            line 7: 12
            line 8: 40
    
      static {};
        descriptor: ()V
        flags: ACC_STATIC
        Code:
          stack=1, locals=0, args_size=0
             0: iconst_1
             1: putstatic     #10                 // Field i:I
             4: ldc           #14                 // String string
             6: putstatic     #8                  // Field s:Ljava/lang/String;
             9: return
          LineNumberTable:
            line 2: 0
            line 3: 4
    }
    SourceFile: "CheckoutJavaP.java"
    
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  • 2021-01-31 03:07

    it stands for java printer....

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  • 2021-01-31 03:12

    The javap command disassembles one or more class files. Its output depends on the options used. If no options are used, javap prints out the package, protected, and public fields and methods of the classes passed to it. javap prints its output to stdout.

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  • 2021-01-31 03:14

    By default, javap prints declarations of the non-private members of each of the classes specified on the command line

    Reference : http://docstore.mik.ua/orelly/java/javanut/ch16_08.htm

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  • 2021-01-31 03:15

    It lists all the methods and variable the specified class contains. You just need to paas the class name with javap command on command-line. e.g. C:\jdk1.3\bin> javap java.lang.Object it will list all the methods Object class contains.

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  • 2021-01-31 03:16

    It prints the methods declarations in your class and its a very good way to see the how your compiler has interpreted your code and convert your source file into .class format.

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