PostgreSQL, 158 characters

select'public static boolean isPowerOfTen(long input) {
  return
   '||string_agg(' input == 1'||repeat('0',x)||'L','
  ||')||';
}'from generate_series(0,18)x

05AB1E, 99 97 96 94 93 87 bytes

Code:

“‚Æ£‹ÒŒ€ˆPowerOfTen(“?“¢„î®) {
 «‡
   “?19FN0›i"  ||"?}’ î® == ’?N°?'L?N18Qi';,"}"?}"",

Try it online!

Uses CP-1252 encoding.

Java, 217 215 220 219 192 bytes

Golfed:

public static String b(){String s="public static boolean isPowerOfTen(long input) {\n  return\n    input == 1L",z="";for(int i=0;i++<18;){z+="0";s+="\n  || input == 1"+z+"L";}return s+";\n}";}

Ungolfed:

  public static String a(){
    String s = "public static boolean isPowerOfTen(long input) {\n  return\n    input == 1L", z="";
    for (int i=0; i++ < 18;) {
        z += "0";
        s += "\n  || input == 1"+z+"L";
    }
    return s + ";\n}";
  }

(first answer, wuhu)

Thanks!
-2 bytes: user902383
-1 byte: Denham Coote

Changes:

• used tabs instead of spaces
• missed the last line of output: 18 -> 19
• removed inner loop
• changed from printing to returning string

Vim 97 keystrokes

ipublic static boolean isPowerOfTen(long input) {
  return
  || input == 1L<esc>qyYpfLi0<esc>q16@yo}<esc>3Gxx

Well, I'm on a roll today with vim producing java, so why not continue the trend!

CJam, 52 characters

YA#_("𐀑򀺸󆚜񸎟񜏓񞍁򛟯󩥰󾐚򉴍􍼯𹾚򶗜򳙯󭧐񹷜񊽅𸏘򴂃򦗩󧥮𤠐𰑈򶂤𘏧󔆧򇃫󡀽򊠑񊩭򯐙񛌲񊚩𤱶𻺢"f&bY7#b:c~

Try it online!

Stage 1

Using Unicode characters U+10000 to U+10FFFF, we can encode 20 bits in a single character. CJam uses 16-bit characters internally, so each one will be encoded as a pair of [surrogates][3], one in the range from U+D800 to U+DBFF, followed by one in the range from U+DC00 to U+DFFF.

By taking the bitwise AND of each surrogate with 1023, we obtain the 10 bits of information it encodes. We can convert the resulting array from base 1024 to base 128 to decode an arbitrary string of Unicode characters outside the BMP to an ASCII string.

The code does the following:

YA#    e# Push 1024 as 2 ** 10.
_(     e# Copy and decrement to push 1023.

"𑅰󻢶񹱨񉽌񍍎񄆋򎿙򧃮񑩹󠷽􂼩􉪦񭲣񶿝򭁩󭰺􄔨񍢤𘎖񮧗򦹀𹀠񐢑񜅈𠟏򘍎󾇗򲁺􅀢򅌛񎠲򦙤򃅒𹣬񧵀򑀢"

f&     e# Apply bitwise AND with 1023 to each surrogate character.
b      e# Convert the string from base 1024 to integer.
Y7#    e# Push 128 as 2 ** 7.
b      e# Convert the integer to base 128.
:c     e# Cast each base-128 to an ASCII character.
~      e# Evaluate the resulting string.

Stage 2

The decoding process from above yields the following source code (98 bytes).

"public static boolean isPowerOfTen(long input) {
  return
   ""L
  || input == ":S6>AJ,f#S*"L;
}"

Try it online!

The code does the following:

e# Push the following string.

"public static boolean isPowerOfTen(long input) {
  return
   "

e# Push the following string and save it in S.

"L
  || input == ":S

e# Discard the first 6 characters of S. The new string begins with " input".

6>

e# Elevate 10 (A) to each exponent below 19 (J).

AJ,f#

e# Join the resulting array, using the string L as separator.

S*

e# Push the following string.

"L;
}"

Pyth, 118 106 103 bytes

s[."
{Z-L¡JxÙÿ
LæÝ<­í?¢µb'¥ÜA«Ç}h¹äÚÏß"\nb*4dj"\n  || "ms[." uøs|ÀiÝ"*d\0\L)U19\;b\}

Try it online!

All this string hardcoding really eats a lot of bytes up, but nothing I can do about it.

Update: Saved 3 bytes by using a packed string. Thanks @user81655 for the hint!

C# (CSI) 181 180 179 byte

string i=" input == 1",e="public static bool";Console.Write(e+@"ean isPowerOfTen(long input) {
  return
   "+i+string.Join(@"L
  ||"+i,e.Select((_,x)=>new string('0',x)))+@"L;
}")

There is only one little trick involved. The straight forward way to write this would be:

string.Join("L\n  || input == 1",Enumerable.Range(0,18).Select(x=>new string('0',x)))

by using the string with the first 18 characters of the text which I need anyways I can get rid off the lengthy Enumerable.Range. This works because string implements IEnumerable and there is a version of Select that hands the item (not needed) and the index which we want to the lambda function.

PowerShell, 120 bytes

'public static boolean isPowerOfTen(long input) {'
'  return'
"   $((0..18|%{" input == 1"+"0"*$_})-join"L`n  ||")L;`n}"

The first two lines are simply string literals, which are output as-is.

The third line starts with three spaces, and ends with L;`n}" to finish off the last couple bytes. The middle bit inside the script block $(...) is constructed by for-looping % from 0 to 18 and each iteration constructing a string that starts with input == 1 concatenated with the corresponding number of zeros. This will spit out an array of strings. We then -join each element of the array with L`n || to achieve the newline-pipes. That big string is the output of the script block, which gets inserted automatically into the middle and output.

PS C:\Tools\Scripts\golfing> .\go-generate-some-java.ps1
public static boolean isPowerOfTen(long input) {
  return
    input == 1L
  || input == 10L
  || input == 100L
  || input == 1000L
  || input == 10000L
  || input == 100000L
  || input == 1000000L
  || input == 10000000L
  || input == 100000000L
  || input == 1000000000L
  || input == 10000000000L
  || input == 100000000000L
  || input == 1000000000000L
  || input == 10000000000000L
  || input == 100000000000000L
  || input == 1000000000000000L
  || input == 10000000000000000L
  || input == 100000000000000000L
  || input == 1000000000000000000L;
}

Javascript, 172 157 152 150 148 bytes

p=>`public static boolean isPowerOfTen(long input) {
  return${[...Array(19)].map((x,i)=>`
  ${i?'||':' '} input == 1${'0'.repeat(i)}L`).join``};
}`

f=p=>`public static boolean isPowerOfTen(long input) {
  return${[...Array(19)].map((x,i)=>`
  ${i?'||':' '} input == 1${'0'.repeat(i)}L`).join``};
}`

document.body.innerHTML = '<pre>' + f() + '</pre>'

C, 158 155 bytes

i;main(){for(puts("public static boolean isPowerOfTen(long input) {\n  return");i<19;)printf("  %s input == 1%0.*dL%s\n",i++?"||":" ",i,0,i<18?"":";\n}");}

Try it online here.

Jelly, 75 bytes

(These are bytes in Jelly's custom codepage.)

0r18⁵*;@€⁶j“¢œḤḅg^NrÞḢ⁷ẉ»“⁵®UẆƓḃÐL⁴ṖịṛFþẈ¹9}¶ ƁḋȮ¦sẒẆd€Ḟɼ¿ỌṀP^µ\f@»;;“L;¶}”

Try it here.

Explanation

0r18      Range [0..18]
⁵*        Take the 10^ of each number
;@€⁶      Prepend a space to each number
j“...»    Join by compressed string "L\n  || input =="
“...»;    Prepend compressed string "public static ... =="
;“L;¶}”   Append "L;\n}"

Vimscript, 120 bytes

Might as well use the right tool for the job.

This assumes that autoindent, etc have not been set. ^[ and ^M are escape characters for the ESC and CR characters respectively.

The a macro duplicates the current line and adds a 0 to the copy. The :norm line generates all the boilerplate and the indent == 1L line, then uses a to create the others.

:let @a='yyp$i0^['
:norm ipublic static boolean isPowerOfTen(long input) {^M  return^M  || input == 1L^[18@a$a;^M}
:3s/||/ /

In case the trailing spaces the sample output had on two lines weren't typos, here's a 126 byte version that includes them.

:let @a='yyp/L^Mi0^['
:norm ipublic static boolean isPowerOfTen(long input) {^M  return ^M  || input == 1L^[18@a$a;^M}   
:3s/||/ /

Oracle SQL 9.2, 311 bytes

SELECT REPLACE(REPLACE('public static boolean isPowerOfTen(long input) {'||CHR(10)||'  return'||c||';'||'}', 'n  ||', 'n'||CHR(10)||'   '),CHR(10)||';', ';'||CHR(10)) FROM(SELECT LEVEL l,SYS_CONNECT_BY_PATH('input == '||TO_CHAR(POWER(10,LEVEL-1))||'L'||CHR(10),'  || ')c FROM DUAL CONNECT BY LEVEL<20)WHERE l=19

Perl 5 - 130 141

@s=map{'input == 1'.0 x$_."L\n  ||"}0..18;$s[$#s]=~s/\n  \|\|/;\n}/g;print"public static boolean isPowerOfTen(long input){\n  return\n    @s"

EDIT: fixed to have exact indentation

ES6, 139 bytes

_=>"0".repeat(19).replace(/./g,`
 || input == 1$\`L`).replace(`
 ||`,`public static boolean isPowerOfTen(long input) {
  return\n  `)+`;
}`

I do so love these triangle generation questions.

Kotlin, 194 193 characters

fun main(u:Array<String>){var o="public static boolean isPowerOfTen(long input) {\n\treturn"
var p:Long=1
for(k in 0..18){
o+="\n\t"
if(k>0)o+="||"
o+=" input == ${p}L"
p*=10
}
print("$o;\n}")}

Test it at http://try.kotlinlang.org/

Ruby, 125 119 bytes

$><<'public static boolean isPowerOfTen(long input) {
  return
   '+(0..19).map{|i|" input == #{10**i}L"}*'
  ||'+';
}'

Thanks to manatwork for -6 bytes!

Javascript 175 bytes

Let's do this regularly

var s = "public static boolean isPowerOfTen(long input) {\n\treturn\n\t\tinput == 1";
for (var i = 1; i < 20; i++) {
    s += "\n\t|| input == 1";
    for (var j = 0; j < i; j++) {
        s += "0";
    }
    s += "L" ;
}
s += ";\n}";
alert(s);

Pretty small. Now, some javascript magic, like no semicolons needed, or no var's, etc.:

k="input == 1"
s="public static boolean isPowerOfTen(long input) {\n\treturn\n\t\t"+k+"L"
for(i=1;i<20;i++){s+="\n\t|| "+k
for(j=0;j<i;j++)s+="0";s+="L"}s+=";\n}"
alert(s)

Python (3.5) 137 136 bytes

print("public static boolean isPowerOfTen(long input) {\n  return\n   ",'\n  || '.join("input == %rL"%10**i for i in range(19))+";\n}")

Previous version

print("public static boolean isPowerOfTen(long input) {\n  return\n   ",'\n  || '.join("input == 1"+"0"*i+"L"for i in range(19))+";\n}")

jq, 123 characters

(121 characters code + 2 characters command line option.)

"public static boolean isPowerOfTen(long input) {
  return
   \([range(19)|" input == 1\("0"*.//"")L"]|join("
  ||"));
}"

Sample run:

bash-4.3$ jq -nr '"public static boolean isPowerOfTen(long input) {
>   return
>    \([range(19)|" input == 1\("0"*.//"")L"]|join("
>   ||"));
> }"'
public static boolean isPowerOfTen(long input) {
  return
    input == 1L
  || input == 10L
  || input == 100L
  || input == 1000L
  || input == 10000L
  || input == 100000L
  || input == 1000000L
  || input == 10000000L
  || input == 100000000L
  || input == 1000000000L
  || input == 10000000000L
  || input == 100000000000L
  || input == 1000000000000L
  || input == 10000000000000L
  || input == 100000000000000L
  || input == 1000000000000000L
  || input == 10000000000000000L
  || input == 100000000000000000L
  || input == 1000000000000000000L;
}

On-line test (Passing -r through URL is not supported – check Raw Output yourself.)

Java 215

class A{public static void main(String[]a){String s="public static boolean isPowerOfTen(long input) {\n  return\n   ";for(long i=1;i>0;i*=10)s+=" input == "+i+"L\n  ||";System.out.print(s.substring(0,515)+";\n}");}}

or if

you write a shorter program or function that outputs this function for you

can be interpreted to allow for writing a Java method that returns a String, then this can be golfed down to 171:

String a(){String s="public static boolean isPowerOfTen(long input) {\n  return\n   ";for(long i=1;i>0;i*=10)s+=" input == "+i+"L\n  ||";return s.substring(0,515)+";\n}";}

ANSI-SQL, 252 characters

WITH t as(SELECT '   'x,1 c,1 l UNION SELECT'  ||',c*10,l+1 FROM t WHERE l<19)SELECT 'public static boolean isPowerOfTen(long input) {'UNION ALL SELECT'  return 'UNION ALL SELECT x||' input == '||c||'L'||SUBSTR(';',1,l/19)FROM t UNION ALL SELECT'}   ';

Ungolfed:

WITH t as (SELECT '   ' x,1 c,1 l UNION
           SELECT '  ||',c*10,l+1 FROM t WHERE l<19)
SELECT 'public static boolean isPowerOfTen(long input) {' UNION ALL
SELECT '  return ' UNION ALL
SELECT x||' input == '||c||'L'||SUBSTR(';',1,l/19) FROM t UNION ALL
SELECT '}   ';

Not a serious attempt, just poking at the Oracle SQL/T-SQL entries.

JavaScript (Node.js), 156 bytes

s="public static boolean isPowerOfTen(long input) {\n  return "
for(i=1;i<1e19;i*=10)s+="\n  "+(i-1?"||":" ")+" input == "+i+"L"
console.log(s+";\n}   \n")

The i-1 will only be 0 (and thus falsey) on the very first round (it's just slightly shorter than i!=1.

Suggestions welcome!

Perl 5, 137 bytes

Not based on the previous Perl answer, but it is somehow shorter. I believe it can be shortened down again by taking care of the first "input" inside the loop, but I didn't try anything yet (at work atm)

$i="input";for(1..18){$b.="  || $i == 1"."0"x$_."L;\n"}print"public static boolean isPowerOfTen(long $i) {\n  return\n    $i == 1L;\n$b}"

CJam, 112 chars

"public static boolean isPowerOfTen(long input) {
  return
    input == 1"19,"0"a19*.*"L
  || input == 1"*"L;
}"

AWK+shell, 157 bytes

echo 18|awk '{s="input == 1";printf"public static boolean isPowerOfTen(long input) {\n return\n    "s"L";for(;I<$1;I++)printf"\n  ||%sL",s=s"0";print";\n}"}'

The question did say to count everything you would have to type. This does have the added bonus of being able to select how many lines would be placed in the isPowersOfTen method when the boss inevitably changes his mind.

Batch, 230 208 bytes

@echo off
echo public static boolean isPowerOfTen(long input) {
echo   return
set m=input == 1
echo    %m%L
for /l %%a in (1,1,17) do call :a
call :a ;
echo }
exit/b
:a
set m=%m%0
echo  ^|^| %m%L%1

Edit: Saved 22 bytes by avoiding repeating input == and reusing the subroutine for the line with the extra semicolon.

T-SQL 289, 277, 250, 249 bytes

SELECT'public static boolean isPowerOfTen(long input){return '+STUFF((SELECT'||input=='+N+'L 'FROM(SELECT TOP 19 FORMAT(POWER(10.0,ROW_NUMBER()OVER(ORDER BY id)),'F0')N FROM syscolumns)A FOR XML PATH(''),TYPE).value('.','VARCHAR(MAX)'),1,2,'')+';}'

Update: Thanks @Bridge, I found a few more spaces too :)

Update2: Changed CTE to subquery -27 chars :) Update3: Another space bites the dust @bridge :)

R, 185 bytes

Golfed

options(scipen=999);p=paste;cat(p("public static boolean isPowerOfTen(long input) {"," return",p(sapply(0:19,function(x)p(" input == ",10^x,"L",sep="")),collapse="\n ||"),"}",sep="\n"))

Ungolfed

options(scipen=999)
p=paste
cat(
  p("public static boolean isPowerOfTen(long input) {",
        " return",
        p(sapply(0:19,function(x)p(" input == ",10^x,"L",sep="")),collapse="\n ||"),
        "}",
        sep="\n")
)

Perl 6 (115 bytes)

say "public static boolean isPowerOfTen(long input) \{
  return
   {join "L
  ||",(" input == "X~(10 X**^19))}L;
}"

X operator does list cartesian product operation, for example 10 X** ^19 gives powers of ten (from 10 to the power of 0 to 19, as ^ is a range operator that counts from 0). Strings can have code blocks with { (which is why I escape the first instance of it).