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摘要: 在Java1.5中创建可变参数[Varargs]
Guitar guitar = new Guitar("Bourgeois", "Country Boy Deluxe",
GuitarWood.MAHOGANY, GuitarWood.ADIRONDACK,1.718);
Guitar guitar = new Guitar("Martin", "HD-28");
Guitar guitar = new Guitar("Collings", "CW-28"
GuitarWood.BRAZILIAN_ROSEWOOD, GuitarWood.ADIRONDACK,1.718,
GuitarInlay.NO_INLAY, GuitarInlay.NO_INLAY);
This code calls three versions of the constructor of a (fictional) Guitar class, meaning that information can be supplied when it’s available,rather than forcing a user to know everything about their guitar at one time (many professionals couldn’t tell you their guitar’s width at the nut).
Here are the constructors used:
public Guitar(String builder, String model) {
}
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,
float nutWidth) {
}
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,
float nutWidth,
GuitarInlay fretboardInlay, GuitarInlay topInlay) {
}
public Guitar(String builder, String model) {
}
public Guitar(String builder, String model,GuitarWood backSidesWood, GuitarWood topWood,float nutWidth) {
}
public Guitar(String builder, String model,GuitarWood backSidesWood, GuitarWood topWood,float nutWidth,
GuitarInlay fretboardInlay, GuitarInlay topInlay) {
}
Guitar guitar = new Guitar("Collings", "CW-28"
GuitarWood.BRAZILIAN_ROSEWOOD, GuitarWood.ADIRONDACK,1.718,
GuitarInlay.NO_INLAY, GuitarInlay.NO_INLAY,"Enlarged Soundhole", "No Popsicle Brace");
Guitar guitar = new Guitar("Martin", "HD-28V","Hot-rodded by Dan Lashbrook", "Fossil Ivory Nut","Fossil Ivory Saddle", "Low-profile bridge pins");
public Guitar(String builder, String model, String...features);
Guitar guitar = new Guitar("Martin", "HD-28V","Hot-rodded by Dan Lashbrook", "Fossil Ivory Nut","Fossil Ivory Saddle", "Low-profile bridge pins");
Guitar guitar = new Guitar("Bourgeois", "OMC","Incredible flamed maple bindings on this one.");
Guitar guitar = new Guitar("Collings", "OM-42","Once owned by Steve Kaufman--one of a kind");
You could add the same variable-length argument to the other constructors:
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,float nutWidth, String... features)
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,float nutWidth,
GuitarInlay fretboardInlay,GuitarInlay topInlay,String... features)
package com.oreilly.tiger.ch05;
public class Guitar {
private String builder;
private String model;
private float nutWidth;
private GuitarWood backSidesWood;
private GuitarWood topWood;
private GuitarInlay fretboardInlay;
private GuitarInlay topInlay;
private static final float DEFAULT_NUT_WIDTH = 1.6875f;
public Guitar(String builder, String model, String... features) {
this(builder, model, null, null, DEFAULT_NUT_WIDTH, null, null, features);
}
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,
float nutWidth, String... features) {
this(builder, model, backSidesWood, topWood, nutWidth, null, null, features);
}
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,float nutWidth,
GuitarInlay fretboardInlay, GuitarInlay topInlay,String... features) {
this.builder = builder;
this.model = model;
this.backSidesWood = backSidesWood;
this.topWood = topWood;
this.nutWidth = nutWidth;
this.fretboardInlay = fretboardInlay;
this.topInlay = topInlay;
}
}
public Guitar(String builder, String model, String... features)
public Guitar(String builder, String model, String[] features)
public Guitar(String builder, String model,
String... features, float... stringHeights)
Guitar guitar = new Guitar("Martin", "D-18");
public Guitar(String builder, String model)
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,float nutWidth,
GuitarInlay fretboardInlay, GuitarInlay topInlay,String... features) {
this.builder = builder;
this.model = model;
this.backSidesWood = backSidesWood;
this.topWood = topWood;
this.nutWidth = nutWidth;
this.fretboardInlay = fretboardInlay;
this.topInlay = topInlay;
for (String feature : features) {
System.out.println(feature);
}
}
public static int max(int first, int... rest) {
int max = first;
for (int i : rest) {
if (i > max)
max = i;
}
return max;
}
package com.oreilly.tiger.ch05;
public class Guitar {
private String builder;
private String model;
private float nutWidth;
private GuitarWood backSidesWood;
private GuitarWood topWood;
private GuitarInlay fretboardInlay;
private GuitarInlay topInlay;
private String[] features;
private static final float DEFAULT_NUT_WIDTH = 1.6875f;
public Guitar(String builder, String model, String... features) {
this(builder, model, null, null, DEFAULT_NUT_WIDTH, null, null, features);
}
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,
float nutWidth, String... features) {
this(builder, model, backSidesWood, topWood, nutWidth, null, null, features);
}
public Guitar(String builder, String model,
GuitarWood backSidesWood, GuitarWood topWood,
float nutWidth,
GuitarInlay fretboardInlay, GuitarInlay topInlay,
String... features) {
this.builder = builder;
this.model = model;
this.backSidesWood = backSidesWood;
this.topWood = topWood;
this.nutWidth = nutWidth;
this.fretboardInlay = fretboardInlay;
this.topInlay = topInlay;
this.features = features;
}
}
//变量声明
private List features;
//在方法中或是构造器中的书写
this.features = java.util.Arrays.asList(features);
public static int max(int first, int... rest) {
int max = first;
for (int i : rest) {
if (i > max)
max = i;
}
return max;
}
int max = MathUtils.max(1, 4);
int max = MathUtils.max(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
int max = MathUtils.max(18, 8, 4, 2, 1, 0);
int[] numbers = getListOfNumbers( );
public static int max(int... values) {
int max = Integer.MIN_VALUE;
for (int i : values) {
if (i > max)
max = i;
}
return
//用这种方法来取得数字
int[] numbers = getListOfNumbers( );
int max = MathUtils.max(numbers);
package com.oreilly.tiger.ch05;
public class MathUtils {
public static int max(int... values) {
if (values.length == 0) {
throw new IllegalArgumentException("No values supplied.");
}
int max = Integer.MIN_VALUE;
for (int i : values) {
if (i > max)
max = i;
}
return max;
}
}
int max = MathUtils.max(myArray);
int max = MathUtils.max(new int[] { 2, 4, 6, 8 });
int max = MathUtils.max(2, 4, 6, 8);
int max = MathUtils.max(0);
int max = MathUtils.max( );
private String print(Object... values) {
StringBuilder sb = new StringBuilder( );
for (Object o : values) {
sb.append(o)
.append(" ");
}
return sb.toString( );
}
private String print(String... values) {
StringBuilder sb = new StringBuilder( );
for (Object o : values) {
sb.append(o)
.append(" ");
}
return sb.toString( );
}
private String print(Object... values) {
StringBuilder sb = new StringBuilder( );
for (Object o : values) {
sb.append(o)
.append(" ");
}
return sb.toString( );
}
System.out.printf("The balance of %s's account is $%(,6.2f\n",account.getOwner().getFullName( ),account.getBalance( ));
PrintStream printf(String format, Object... args)
PrintStream printf(String format, Object[] args)
Object[] objectArray = getObjectArrayFromSomewhereElse( );
out.printf("Description of object array: %s\n", obj);
public Object[] getObjectArrayFromSomewhereElse( ) {
return new String[] {"Hello", "to", "all", "of", "you"};
}
out.printf("Description of object array: %s\n", obj);
run-ch05:
[echo] Running Chapter 5 examples from Java Tiger: A Developer's Notebook
[echo] Running VarargsTester...
[java] Hello
out.printf("Description of object array: %s\n", new Object[] { obj });
out.printf("Description of object array: %s\n", (Object)obj);
run-ch05:
[echo] Running Chapter 5 examples from Java Tiger: A Developer's Notebook
[echo] Running VarargsTester...
[java] [Ljava.lang.String;@c44b88