?? holders30.java
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// generics/Holders30.java
// TIJ4 Chapter Generics, Exercise 30, page 696
// Create a Holder for each of the primitive wrapper types, and show that
// autoboxing and autounboxing works for the set() and get() methods of
// each instance.
import static org.greggordon.tools.Print.*;
public class Holders30 {
public static void main(String[] args) {
Holder<Character> charHolder = new Holder<Character>();
Holder<Byte> byteHolder = new Holder<Byte>();
Holder<Short> shortHolder = new Holder<Short>();
Holder<Integer> intHolder = new Holder<Integer>();
Holder<Long> longHolder = new Holder<Long>();
Holder<Float> floatHolder = new Holder<Float>();
Holder<Double> doubleHolder = new Holder<Double>();
// Autoboxing and autounboxing work:
charHolder.set('a');
print(charHolder.get() + ", ");
println(charHolder.get().getClass());
char c = charHolder.get();
println("char c = charHolder.get() = " + c);
byte b = 1;
byteHolder.set(b);
print(byteHolder.get() + ", ");
println(byteHolder.get().getClass());
byte bb = byteHolder.get();
println("byte bb = byteHolder.get() = " + bb);
short s = 1;
shortHolder.set(s);
print(shortHolder.get() + ", ");
println(shortHolder.get().getClass());
short ss = shortHolder.get();
println("short ss = shortHolder.get() = " + ss);
intHolder.set(1);
print(intHolder.get() + ". ");
println(intHolder.get().getClass());
int i = intHolder.get();
println("int i = intHolder.get() = " + i);
long l = 2;
longHolder.set(l);
print(longHolder.get() + ", ");
println(longHolder.get().getClass());
long ll = longHolder.get();
println("long ll = longHolder.get() = " + ll);
float f = 1f;
floatHolder.set(f);
print(floatHolder.get() + ", ");
println(floatHolder.get().getClass());
float ff = floatHolder.get();
println("float ff = floatHolder.get() = " + ff);
double d = 1.1;
doubleHolder.set(d);
print(doubleHolder.get() + ", ");
println(doubleHolder.get().getClass());
double dd = doubleHolder.get();
println("double dd = doubleHolder.get() = " + dd);
}
}
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