Passing System.out.println (); as an argument in a method

Question

I want to pass System.out.println();as an argument, but the compiler will not allow me to return the void type as an argument. that's what i want for this.

public class Array {

    public static void main(String args[]) {
        a(data());
    }

    static void a(e) {
        System.out.println(e);
    }

    static void data() {
        ...
    }
}

So, what you want to a(data());look after compilation is something like this.

a(data()) = System.out.println(data(){...});

In the end I want to cut back System.out.println().

Answer 1

What you are doing here does not pass System.out.println()as an argument; you are trying to pass an argumentSystem.out.println()

data() String int - , void, - .

e a(), data().

a(data()); -.

:

public static void main(String args[]) {
    a(data());
}

// shorthand for System.out.println
static void a(String e) {
    System.out.println(e);
}

// a method that returns some data
static String data() {
    // replace this with whatever actual data you want to return
    return "This is some data...";
}

Answer 2

System.out.println, void, , :

System.out.println(argument)

Answer 3

, / System.out.println . , ( ...), Java 8 .

:

@FunctionalInterface 
public interface Action {
    void run(String param);
}

:

public class MyClass {
    public void execute(Action action){
       action.run("Hello!");
    }
}

:

MyClass c = new MyClass();
c.execute(System.out::println);

Answer 4

println String
:

static void data() {
    int array[] = {1,5,6};
    int alength = array.length;
    System.out.println("  Location\tData");
    for(int i=0;i<alength;i++) {
        System.out.println("  " + i + "\t\t" + array[i]);
    }
}

:

static String data() {
    int array[] = {1,5,6};
    int alength = array.length;
    //Note extra \n symbol for new line
    String result = "  Location\tData\n";
    for(int i=0;i<alength;i++) {
        result += "  " + i + "\t\t" + array[i] + "\n";
    }
    return result;
}

a(), String :

static void a(String result) {System.out.println(result);}

:

public class Array {
    public static void main(String args[]) {
        println(data());
    }

    // I strongly advise to use understandable naming
    // a() is completely uninformative
    static void println(String result) {
        System.out.println(result);
    }

    static String data() {
        int array[] = { 1, 5, 6 };
        int alength = array.length;
        // Note extra \n symbol for new line
        String result = "  Location\tData\n";
        for (int i = 0; i < alength; i++) {
            result += "  " + i + "\t\t" + array[i] + "\n";
        }
        return result;
    }
}

Answer 5

, .

Objective-C; :

void (^action)(NSString *s) = ^(NSString *s){ NSLog(s); }

:

action(@"Hello World");

C, http://en.wikipedia.org/wiki/Blocks_(C_language_extension).

Answer 6

I want to change this code

    package Array;
import java.util.Random;

public class Array {
    public static void main(String args[]) {
        data();
        a();
        random();
        a();
        array();
        a();
        rows();
        a();
        System.out.println("average " + average(45,15,15,48,97,45));

    }

    static String s() {
        return "helloWorld";
    }

    static void a() {System.out.println();}

    static void data() {
        int array[] = {1,5,6};
        int alength = array.length;
        System.out.println("  Location\tData");
        for(int i=0;i<alength;i++) {
            System.out.println("  " + i + "\t\t" + array[i]);
        }
    }

    static void random() {
        Random rdm = new Random();
        int freq[] = new int[7];

        for(int i=1;i<1000;i++) {
            ++freq[1+rdm.nextInt(6)];
        }
        System.out.println("Face\tFrequency");
        int frequence = freq.length;
        for(int face=1;face<frequence;face++) {
            System.out.println(face+"\t"+freq[face]);
        }
    }

    static void array() {
        String po[] = {"lala","po","tinkiwinki","disty"};
        for(String lala: po) {
            System.out.print(lala + " ");
        }
        System.out.println();
    }

    static void rows() {
        int arrays[][]= {{1,5,78,15},{45,67},{875,15687,158,4515,23,2,2}};

        for(int i=0;i<arrays.length;i++) {
            for(int j=0;j<arrays[i].length;j++) {
                System.out.print(arrays[i][j]+"\t");
            }
            System.out.println();
        }
    }

    static int average(int...numbers) {
        int total=0;
        for(int x:numbers)
            total += x;
        return total/numbers.length;
    }
}
class time {
    int h, m, s;
    void setTime(int hour,int minute,int second) {
        h = ((hour>=0 && hour<=24) ? hour : 0);
        m = ((minute>=0 && minute<=60) ? minute : 0);
        s = ((second>=0 && second<=60) ? second : 0);
    }


into this type of code for main.


    a(data());
    a(random());
    a(array());
    a(rows());
a("average " + average(45,15,15,48,97,45));