如何比较字符串？

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最佳答案

This line:

if(str2==${str}){

Should be:

if( str2 == str ) {

The ${ and } will give you a parse error, as they should only be used inside Groovy Strings for templating

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If you don't want to check on upper or lowercases you can use the following method.

String str = "India"
compareString(str)


def compareString(String str){
def str2 = "india"
if( str2.toUpperCase() == str.toUpperCase() ) {
println "same"
}else{
println "not same"
}
}

So now if you change str to "iNdIa" it'll still work, so you lower the chance that you make a typo.

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The shortest way (will print "not same" because String comparison is case sensitive):

def compareString = {
it == "india" ? "same" : "not same"
}


compareString("India")

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This should be an answer

str2.equals( str )

If you want to ignore case

str2.equalsIgnoreCase( str )

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In Groovy, null == null gets a true. At runtime, you won't know what happened. In Java, == is comparing two references.

This is a cause of big confusion in basic programming, Whether it is safe to use equals. At runtime, a null.equals will give an exception. You've got a chance to know what went wrong.

Especially, you get two values from keys not exist in map(s), == makes them equal.

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use def variable, when you want to compare any String. Use below code for that type of comparison.

def variable name = null

SQL query give you some return. Use function with return type def.

def functionname(def variablename){

return variable name

}

if ("$variable name" == "true"){

}

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String str = "saveMe"
compareString(str)


def compareString(String str){
def str2 = "saveMe"


// using single quotes
println 'single quote string class' + 'String.class'.class
println str + ' == ' + str2 + " ? " + (str == str2)
println ' str = ' +  '$str' //  interpolation not supported


// using double quotes, Interpolation supported
println "double quoted string with interpolation " + "GString.class $str".class
println "double quoted string without interpolation " + "String.class".class
println "$str equals $str2 ? " + str.equals(str2)
println '$str == $str2 ? ' + "$str==$str2"
println '${str == str2} ? ' + "${str==str2} ? "


println '$str equalsIgnoreCase $str2 ? ' + str.equalsIgnoreCase(str2)


println '''
triple single quoted Multi-line string, Interpolation not supported $str ${str2}
Groovy has also an operator === that can be used for objects equality
=== is equivalent to o1.is(o2)
'''
println '''
triple quoted string
'''
println 'triple single quoted string ' + '''' string '''.class


println """
triple double quoted Multi-line string, Interpolation is supported $str == ${str2}
just like double quoted strings with the addition that they are multiline
'\${str == str2} ? ' ${str == str2}
"""
println 'triple double quoted string ' + """ string """.class
}

output:

single quote string classclass java.lang.String
saveMe == saveMe ? true
str = $str
double quoted string with interpolation class org.codehaus.groovy.runtime.GStringImpl
double quoted string without interpolation class java.lang.String
saveMe equals saveMe ? true
$str == $str2 ? saveMe==saveMe
${str == str2} ? true ?
$str equalsIgnoreCase $str2 ? true


triple single quoted Multi-line string, Interpolation not supported $str ${str2}
Groovy has also an operator === that can be used for objects equality
=== is equivalent to o1.is(o2)




triple quoted string


triple single quoted string class java.lang.String


triple double quoted Multi-line string, Interpolation is supported saveMe == saveMe
just like double quoted strings with the addition that they are multiline
'${str == str2} ? ' true


triple double quoted string class java.lang.String