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Type conversion (JDK1.5)Tag(s): String/Number


JDK1.5 simplifies the operation of conversion between primitive types (such as int) and wrapper types (such as Integer). This feature is called Autoboxing/Unboxing. 
public class Test15 {
  public static void main(String ... args) {
    Integer integer = 1;        // int into Integer
    System.out.println(integer);

    int i = integer + 3;        // mix Integer and ints
    System.out.println(i);

    // output :
    //  1
    //  4
  }
}
In the next example, a boolean is being stored and then retrieved from an ArrayList. The 1.5 version leaves the conversion required to transition to an Boolean and back to the compiler. 
import java.util.Collection.*;
import java.util.*;

public class Test15 {
  public static void main(String ... args) {
    ArrayList<Boolean> list = new ArrayList<Boolean>();
    list.add(0, true);
    boolean flag = list.get(0);
    System.out.println(flag);
  }
}
The old way (pre 1.5) is more cryptic... 
import java.util.Collection.*;
import java.util.*;

public class Test15 {
  public static void main(String args[]) {
    ArrayList list = new ArrayList();
    list.add(0, new Boolean(true));
    boolean flag = ((Boolean)list.get(0)).booleanValue();
    System.out.println(flag);
  }
}
Note : To be able to compile that code with the JDK1.5, you need to specify the switch -source 1.4 on the javac command line.