[Java] Lambda表达式总结

@FunctionalInterface
public  interface NoReturnMultiParam {
    void method(int a, int b);
}
// ---------------------------------------------------------------------------------
NoReturnMultiParam noReturnMultiParam = (int a, int b) -> {
    System.out.println("NoReturnMultiParam param:" + "{" + a +"," + + b +"}");
};
noReturnMultiParam.method(6, 8);
// ---------------------------------------------------------------------------------
NoReturnMultiParam lamdba1 = (a, b) -> {
    System.out.println("简化参数类型");
}; 
lamdba1.method(1, 2);
// ---------------------------------------------------------------------------------
NoReturnMultiParam lambda3 = (a, b) -> println("只有一条语句则可以省略大括号"); 
lambda3.method();

@FunctionalInterface
public  interface ReturnOneParam {
    int method(int a);
}
// ---------------------------------------------------------------------------------
ReturnOneParam returnOneParam = (int a) -> {
    System.out.print("Lambda");
    return  1;
};
// ---------------------------------------------------------------------------------
ReturnOneParam returnOneParam = (a) -> {
    System.out.print("省略类型");
    return  1;
};
// ---------------------------------------------------------------------------------
ReturnOneParam returnOneParam = a -> {
    System.out.print("如果只有一个参数则可以省略参数小括号");
    return  1;
};
// ---------------------------------------------------------------------------------
System.out.print("只有return则可以省略return和大括号")
ReturnOneParam returnOneParam = a -> a + 3;

public class Exe1 {
    public static void main(String[] args) {
        ReturnOneParam lambda1 = a -> doubleNum(a);
        System.out.println(lambda1.method(3));

        // lambda2 引用了已经实现的 doubleNum 方法
        ReturnOneParam lambda2 = Exe1::doubleNum;
        System.out.println(lambda2.method(3));

        Exe1 exe = new Exe1();
        // lambda4 引用了已经实现的 addTwo 方法
        ReturnOneParam lambda4 = exe::addTwo;
        System.out.println(lambda4.method(2));
    }

    public static int doubleNum(int a) {
        return a * 2;
    }

    public int addTwo(int a) {
        return a + 2;
    }
}