####一、方法引用分类

1.构造函数2.静态方法3.实例方法（类型）4.实例方法（对象）

####二、方法引用-构造函数 ClassName::new，示例：

/** * @author Kevin * @date 2017-01-24 */public class ConstructorTest {    public static void main(String[] args) {        Function
    
      function = String::new;        System.out.println(function.apply("SpaceX"));    }}
    

####三、方法引用-静态方法 ClassName::staticMethodName，示例：

/** * @author Kevin * @date 2017-01-24 */public class StaticMethodTest {    public static void main(String[] args) {        Function
    
      function = String::valueOf;        System.out.println(function.apply(1001));    }}
    

####三、方法引用-实例方法（类型） ClassName::instanceMethodName，示例：

/** * @author Kevin * @date 2017-01-24 */public class ClassNameInstanceMethodTest {    public static void main(String[] args) {        Function
    
      function = String::length;        System.out.println(function.apply("Google"));    }}
    

####四、方法引用-实例方法（对象） object::instanceMethodName，示例：

/** * 公司 * * @author Kevin * @date 2017-01-24 */public class Company {    /**     * 编码     */    private String code;    /**     * 公司名称     */    private String name;    public Company() {    }    public Company(String name, String code) {        this.name = name;        this.code = code;    }    public static int compareByCode(Company a, Company b) {        return a.getCode().compareTo(b.getCode());    }    @Override    public String toString() {        return "Company{" +                "code='" + code + '\'' +                ", name='" + name + '\'' +                '}';    }    /**     * 生产     *     * @author Kevin     */    String produce(String productName) {        return getName() + " produces " + productName;    }    public String getCode() {        return code;    }    public void setCode(String code) {        this.code = code;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}/** * @author Kevin * @date 2017-01-24 */public class ObjectInstanceMethodTest {    public static void main(String[] args) {        Company company = new Company();        company.setName("Apple");        Function
    
      converter = company::produce;        System.out.println(converter.apply("iPhone 7"));    }}
    

五、方法引用的综合使用

/** * Java8 方法引用 * * @author Kevin * @date 2017-01-24 */public class MethodReferencesTest {    public static void main(String[] args) {        List
    
      companyList = new ArrayList<>();        companyList.add(new Company("Google", "1002"));        companyList.add(new Company("SpaceX", "1001"));        companyList.add(new Company("Apple", "1003"));        System.out.println("------companyList------");        companyList.forEach(System.out::println);        Company[] listAsArray = companyList.toArray(new Company[companyList.size()]);        // 不使用方法引用        Arrays.sort(listAsArray, new Comparator
     
      () {            @Override            public int compare(Company a, Company b) {                return a.getCode().compareTo(b.getCode());            }        });        // 使用lambada表达式        Arrays.sort(listAsArray,                (Company a, Company b) -> {                    return a.getCode().compareTo(b.getCode());                }        );        // 方法引用(静态方法)        Arrays.sort(listAsArray, Company::compareByCode);        System.out.println("------listAsArray------");        for (int i = 0; i < listAsArray.length; i++) {            System.out.println(listAsArray[i]);        }        class ComparisonProvider {            public int compareByName(Company a,                                     Company b) {                return a.getName().compareTo(b.getName());            }        }        ComparisonProvider comparisonProvider = new ComparisonProvider();        // 方法引用(实例方法)        Arrays.sort(listAsArray, comparisonProvider::compareByName);        // 使用lambada表达式构造函数        Set
      
        companySetLambda =                transferElements(companyList, () -> {                    return new HashSet<>();                });        System.out.println("------companySetLambda------");        companySetLambda.forEach(System.out::println);        // 使用new运算符构造函数        Set
       
         companySet = transferElements(                companyList, HashSet::new);        System.out.println("------companySet------");        companySet.forEach(System.out::println);    }    /**     * 将集合中的元素复制到另一个集合     *     * @author Kevin     */    public static 
        
         , DEST extends Collection
         
          > DEST transferElements( SOURCE sourceCollection, Supplier
          
            collectionFactory) { DEST result = collectionFactory.get(); for (T t : sourceCollection) { result.add(t); } return result; }}/** * 公司 * * @author Kevin * @date 2017-01-24 */public class Company { /** * 编码 */ private String code; /** * 公司名称 */ private String name; public Company() { } public Company(String name, String code) { this.name = name; this.code = code; } public static int compareByCode(Company a, Company b) { return a.getCode().compareTo(b.getCode()); } @Override public String toString() { return "Company{" + "code='" + code + '\'' + ", name='" + name + '\'' + '}'; } /** * 生产 * * @author Kevin */ String produce(String productName) { return getName() + " produces " + productName; } public String getCode() { return code; } public void setCode(String code) { this.code = code; } public String getName() { return name; } public void setName(String name) { this.name = name; }}
          
         
        
       
      
     
    

六、参考文章

1.