Java 10 Developer Features

Java10-Developer-Features.md

Summary and Examples of Java 10 Developer Features

Local variable type inference

local-var-inference-allowed-cases-1.java

var order = new Order(); // order type is inferred

public List<Order> getCustomerOrders(String customerId){...}

var orderList = getCustomerOrders("1234"); //List of orders is inferred

local-var-inference-for-loop.java

var stringArray = new String[11];
Arrays.fill(new String[11], 0, 10, "String Array");

for(var stringInArray: stringArray) { //stringInArray is inferred from stringArray
    System.out.println(stringInArray);
}

local-var-inference-var-is-not-allowed-as-type-name.java

public class var {

}
//Build output
java: 'var' not allowed here
  as of release 10, 'var' is a restricted type name and cannot be used for type declarations

local-var-inferrence-var-in-names.java

//var as a method name is allowed
public void var() {
  System.out.println("Hello var!");
}

public void someMethod() {
  //var as a variable name is allowed
  var var = 3;
}


public class AClass {
 //var as field name is allowed
  public int var; 
}

//package name is allowed
package var;

local-variable-inference-constructors.java

void someMethod() {
 Map<String, List<Order>> orderMap = new HashMap<>();
}

//Can now be written as

void someMethod() {
  var orderMap = new HashMap<String, List<Order>>();
}