☔ WhatIf is kotlin extensions for expressing a single if-else statement, nullable and boolean.
Add a dependency code to your module's build.gradle
file.
dependencies {
implementation "com.github.skydoves:whatif:1.0.7"
implementation "com.github.skydoves:whatif-android:1.0.7" // for android extensions
}
WhatIf
is an expression for invoking whatIf
lambda when the given boolean is true and not-null.
val nullableBoolean: Boolean? = true
whatIf(nullableBoolean) {
log("not-null and true : $nullableBoolean")
}
Here is an extension for nullable booleans.
nullableBoolean.whatIf {
log("not-null and true : $nullableBoolean")
}
The whatIf
expression is basically composed with given
, whatIf
, whatIfNot
.
If the target is null or false, whatIfNot
will be invoked instead of the whatIf
.
If we do not need to handle whatIfNot
case, it can be omitted.
whatIf(
given = nullableBoolean,
whatIf = { log("not-null and true : $nullableBoolean") },
whatIfNot = { log("null or false : $nullableBoolean") }
)
Or here is an extension for nullable boolean.
nullableBoolean.whatIf(
whatIf = { log("not-null and true : $nullableBoolean") },
whatIfNot = { log("not-null or false : $nullableBoolean") }
)
Sometimes we should set builder differently to depend on options.
WhatIf
is useful when using a chaining function like a builder pattern.
It can be applied to any builder patterns like AlertDialog.Builder
or anything.
val balloon = Balloon.Builder(baseContext)
.setArrowSize(10)
.setArrowVisible(true)
.whatIf(nullableBoolean) { setTextColor(Color.YELLOW) }
.whatIf(nullableBoolean, { setText("Hello, whatIf") }, { setText("Good-Bye whatIf") })
.setWidthRatio(1.0f)
.build()
WhatIfNotNull
is an expression for invoking whatIf
lambda when the target object is not null.
val nullableObject: Person? = Person()
nullableObject.whatIfNotNull {
log("$it is not null")
}
And we can handle the null case.
If the target is null, whatIfNot
will be invoked instead of the whatIf
.
nullableObject.whatIfNotNull(
whatIf = { log("$it is not null.") },
whatIfNot = { log("$it is null.") }
)
An expression for invoking whatIf
lambda when the string, collections and array type is not null and not empty.
If the collections or array type target is null or empty, whatIfNot
will be invoked instead of the whatIf
.
val nullableString: String? = "NotNullOrEmpty"
nullableString.whatIfNotNullOrEmpty {
log("$it is not null and not empty")
}
Here is an example for collections.
nullableList.whatIfNotNullOrEmpty {
log("list $it is not null and not empty")
}
And we can handle the null or empty case.
nullableList.whatIfNotNullOrEmpty(
whatIf = { log("list $it is not null and not empty") },
whatIfNot = { log("list is null or empty") }
)
Here is the same example for the array.
nullableArray.whatIfNotNullOrEmpty {
log("$it is not null and not empty")
}
Array, ByteArray, ShortArray, IntArray, LongArray, FloatArray, DoubleArray, BooleanArray, CharArray
List, Map, Set
The basic concept is the same as whatIf
but it is useful when the receiver and the result should be different.
val length = nullableString?.whatIfLet(
given = nullableString.length < 5,
whatIf = { it.length },
whatIfNot = {
log("$it, length can not over than 5.")
5
}
)
We can use default value instead of the whatIfNot
and can be omitted the whatIfNot
.
val length = nullableString?.whatIfLet(
nullableString.length < 5,
default = nullableString.length) {
log("$it, length can not over than 5.")
5
}
An expression for invoking whatIf
lambda when the target boolean is not null and false.
nullableBoolean.whatIfElse {
log("nullableBoolean is not null and false")
}
An expression for invoking whatIf
lambda when the target boolean is true and/or a predicate receiver is true.
nullableBoolean.whatIfAnd(predicate) {
log("nullableBoolean is true and the predicate is also true")
}
nullableBoolean.whatIfOr(predicate) {
log("nullableBoolean is true or the predicate is true")
}
An expression for invoking whatIf
lambda when the Activity's intent extras is not null and not empty.
var foo: String? = null
this@MainActivity.whatIfHasExtras {
foo = "${it.getString("foo")}"
}
And we can handle the null case.
this@MainActivity.whatIfHasExtras(
whatIf = { foo = "${it.getString("foo")}" },
whatIfNot = { log("intent extras is null or empty.") }
)
An expression for invoking whatIf
lambda when the Context is not null.
class WhatIfFragment : Fragment() {
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
whatIfNotNullContext {
Toast.makeText(it, "context is not null!", Toast.LENGTH_SHORT).show()
}
}
}
An expression for invoking whatIf
when the Fragment.getArguments
is not null.
whatIfNotNullArguments {
it.getString("name").whatIfNotNull {
log("my name is $it")
}
}
An expression for invoking whatIf
lambda when the Activity is not null.
whatIfNotNullActivity { activity ->
activity.supportFragmentManager.addOnBackStackChangedListener {
// .. //
}
}
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Copyright 2019 skydoves (Jaewoong Eum)
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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distributed under the License is distributed on an "AS IS" BASIS,
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