Lambda表达式与内部类相比有很多限制，，比如只能为函数式接口创建实例，但是Lambda表达式大大简化了代码的书写。
Lambda表达式的方法引用主要分为下面几类：
1.引用类方法2.引用特定对象的实例方法3.引用某类对象的实例方法4.引用构造方法
下面通过几个实例演示了这几种方法引用的：
1.首先创建下面的接口
/*该函数式接口只包含一个抽象方法convert——用于将String类型的参数转换为Intege类型的返回值*/@FunctionalInterfaceinterface Converter{Integer convert(String from);}/*函数式接口，根据3个参数产生一个String类型的返回值*/@FunctionalInterfaceinterface MakeString{String make(String a,int b,int c);}/*函数式接口，根据输入的title返回一个JFrame对象*/@FunctionalInterfaceinterface GetJFrame{javax.swing.JFrame get(String title);}2.
/*Lambda表达式的方法引用1.引用类方法2.引用特定对象的实例方法3.引用某类对象的实例方法4.引用构造方法5.使用Lambda表达式调用Arrays类的方法*/public class MethodRefer{public static void main(String[] args){//——————————————-1.引用类方法———————————————–/*使用Lambda表达式创建Converter对象由于ambda表达式只有一个参数、一条语句和一个返回值，因此可以省略参数的小括号、语句的花括号和返回值的return关键字*/Converter con_1=from->Integer.valueOf(from);/*方法引用代替Lambda表达式：引用类方法函数式接口中被实现方法的全部参数传给该类方法作为参数*/Converter con_2=Integer::valueOf;Integer val1=con_1.convert("111111");Integer val2=con_2.convert("222222");System.out.println(val1);System.out.println(val2);//—————————————2.引用特定对象的实例方法—————————————–//调用String类的indexOf方法创建对象Converter con_4="sharejava"::indexOf;Integer val4=con_4.convert("java");Converter con_3=from->"sharejava".indexOf(from);Integer val3=con_3.convert("java");System.out.println(val4);System.out.println(val3);//—————————————3.引用某类对象的实例方法—————————————–MakeString ms1=(a,b,c)->a.substring(b,c);String str1=ms1.make("sharejava",5,9);MakeString ms2=String::substring;String str2=ms2.make("sharejava",5,9);System.out.println(str1);System.out.println(str2);//—————————————4.引用构造方法—————————————–GetJFrame g1=title->new javax.swing.JFrame(title);javax.swing.JFrame jf1=g1.get("我的窗口");GetJFrame g2=javax.swing.JFrame::new;javax.swing.JFrame jf2=g2.get("我的窗口");jf1.setVisible(true);jf1.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE );jf1.setBounds(200,200,500,400);}}3.使用Lambda表达式调用Arrays类的方法
我们发现Arrays类的API下包含大量的方法需要函数式接口参数：
static void parallelPrefix(double[] array, DoubleBinaryOperator op) Cumulates, in parallel, each element of the given array in place, using the supplied function.static void parallelPrefix(double[] array, int fromIndex, int toIndex, DoubleBinaryOperator op) Performs parallelPrefix(double[], DoubleBinaryOperator) for the given subrange of the array.static void parallelPrefix(int[] array, IntBinaryOperator op) Cumulates, in parallel, each element of the given array in place, using the supplied function.static void parallelPrefix(int[] array, int fromIndex, int toIndex, IntBinaryOperator op) Performs parallelPrefix(int[], IntBinaryOperator) for the given subrange of the array.static void parallelPrefix(long[] array, int fromIndex, int toIndex, LongBinaryOperator op) Performs parallelPrefix(long[], LongBinaryOperator) for the given subrange of the array.static void parallelPrefix(long[] array, LongBinaryOperator op) Cumulates, in parallel, each element of the given array in place, using the supplied function.static <T> void parallelPrefix(T[] array, BinaryOperator<T> op) Cumulates, in parallel, each element of the given array in place, using the supplied function.static <T> void parallelPrefix(T[] array, int fromIndex, int toIndex, BinaryOperator<T> op) Performs parallelPrefix(Object[], BinaryOperator) for the given subrange of the array.static void parallelSetAll(double[] array, IntToDoubleFunction generator) Set all elements of the specified array, in parallel, using the provided generator function to compute each element.static void parallelSetAll(int[] array, IntUnaryOperator generator) Set all elements of the specified array, in parallel, using the provided generator function to compute each element.static void parallelSetAll(long[] array, IntToLongFunction generator) Set all elements of the specified array, in parallel, using the provided generator function to compute each element.static <T> void parallelSetAll(T[] array, IntFunction<? extends T> generator) Set all elements of the specified array, in parallel, using the provided generator function to compute each element.static <T> void parallelSort(T[] a, Comparator<? super T> cmp) Sorts the specified array of objects according to the order induced by the specified comparator.static <T extends Comparable<? super T>> void parallelSort(T[] a, int fromIndex, int toIndex) Sorts the specified range of the specified array of objects into ascending order, according to the natural ordering of its elements.static <T> void parallelSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> cmp) Sorts the specified range of the specified array of objects according to the order induced by the specified comparator.static void setAll(double[] array, IntToDoubleFunction generator) Set all elements of the specified array, using the provided generator function to compute each element.static void setAll(int[] array, IntUnaryOperator generator) Set all elements of the specified array, using the provided generator function to compute each element.static void setAll(long[] array, IntToLongFunction generator) Set all elements of the specified array, using the provided generator function to compute each element.static <T> void setAll(T[] array, IntFunction<? extends T> generator) Set all elements of the specified array, using the provided generator function to compute each element.这里演示了其中部分方法的应用：
然后拍一些美得想哭的照片，留给老年的自己。
