Java Programming Tutorials

Java programming tutorials with many code examples!

Java Util Map replaceAll(BiFunction)

java.util.Map.replaceAll(BiFunction)

The method Map.replaceAll(BiFunction) replaces each value with the result of applying the given function on the corresponding entry. Rethrows exceptions thrown by the replacement function.

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Spring Field Injection

Spring field injection

This is probably the most common form of Dependency Injection, because it reduces a lot of boilerplate code needed with setter or constructor injections.

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Java Util Map.putIfAbsent(key, value)

java.util.Map.putIfAbsent(key, value)

The method Map.putIfAbsent(key, value) associates the given key with the given value if there is no such association or the current value in map is null. Returns null or the previous value.

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Java Time Clock Tutorial

The java.time.Clock class provides access to the current instant, date and time using a time-zone. These are the main properties of the class:

  • Use of the Clock class is optional, because all key date-time classes have a now() factory method that uses the system clock in the default time zone.
  • Use Dependency Injection framework to provide Clock implementations.

The class declaration is:

public abstract class Clock
       extends Object

Methods inheritance

Objects of this class inherit methods from the following classes:

  • java.lang.Object

Methods of java.time.Clock:

  • boolean equals(Object obj)
    Checks if this clock is equal to another clock.
  • static Clock fixed(Instant fixedInstant, ZoneId zone)
    This method returns a clock that always returns the same time.
  • abstract ZoneId getZone()
    Gets the time-zone being used to create dates and times.
  • int hashCode()
    A hash code for this clock.
  • abstract Instant instant()
    Gets the current instant of the clock.
  • long millis()
    Gets the current millisecond instant of the clock.
  • static Clock offset(Clock baseClock, Duration offsetDuration)
    Obtains a clock based on the given clock with the duration added.
  • static Clock system(ZoneId zone)
    Returns a clock that returns the current instant using best available system clock in the specified zone.
  • static Clock systemDefaultZone()
    Returns a clock that returns the current instant using the best available system clock, converting to date and time using the default time-zone.
  • static Clock systemUTC()
    Returns a clock that returns the current instant using the best available system clock, converting to date and time using the UTC time-zone.
  • static Clock tick(Clock baseClock, Duration tickDuration)
    Returns a clock that returns instants from the specified clock truncated to the nearest occurrence of the specified duration.
  • static Clock tickMinutes(ZoneId zone)
    Obtains a clock that returns the current instant ticking in whole minutes using best available system clock.
  • static Clock tickSeconds(ZoneId zone)
    Returns a clock that returns the current instant ticking in whole seconds using best available system clock.
  • abstract Clock withZone(ZoneId zone)
    Returns a copy of this clock with a different time-zone.
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Spring Setter Injection

Spring Setter Injection

This form of Dependency Injection is used very often, especially for optional dependencies and reconfigurable beans. We’ll show how to use it using Spring annotations.

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Java Lang Tutorial

In Java Lang Tutorial you will learn handy features of classes from java.lang package!

Java Lang Classes

Reflection

Java Lang Exceptions

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Java Util Map merge(key, value, BiFunction)

java.util.Map.merge(key, value, BiFunction)

The method Map.merge(key, value, BiFunction) associates given value with the given key or calculates the new value from the old value and the given one using provided remapping function.

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