java 方法引用

        方法引用使用一对冒号 :: 。方法引用其实就是将形式参数传递给被引用的方法，构造器。

• 静态方法引用 Integer::parseInt

public interface MethodInterFace {
    
    public int  StringtoInt(String i);
}

 
    @Test
    public void TestStaticClassMethodRefrence(){
        MethodInterFace methodInterFace=null;
        methodInterFace=Integer::parseInt;
        System.err.println(methodInterFace.StringtoInt("3"));
    }

• 对象实例方法引用  （对象::方法）

public interface MethodInterFace {
    
    public int  StringtoInt(String i);
}

  @Test
    public void TestClassInstanceMethod(){
        String s="15";
        MethodInterFace methodInterFace=null;
        methodInterFace=s::indexOf;
        methodInterFace.StringtoInt("5");
    }

• 实例方法引用  （类名::成员方法）

public interface MethodInterFace {
    
    public int  StringtoInt(String i);
}

 
    @Test
    public void TestClassMethod(){
        int i = ClassMethodString(Integer::parseInt);
        System.err.println(i);


    }
    public int ClassMethodString(MethodInterFace methodInterFace){
        return methodInterFace.StringtoInt("35");
    }

• 构造方法引用（类名::new）

public interface StudentBuilder {
    public Student studentbuilder(String name,int age);
}

public class Student {
    private String name;
    private int age;

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

    @Test
    public void TestClassConstruct(){
        StudentBuilder studentBuilder=null;
        studentBuilder=Student::new;
    }