如何同时执行“if”和“else”？

Question

Interesting problem:

Change if statement and print out "Hello World"

    public static void main(String[] args) {
        if(){
            System.out.println("Hello");
        }else{
            System.out.println("World");
        }
    }

My solution is to add "!System.out.println("Hello")" in the if statement,But it doesn't work, any ideas?

    public static void main(String[] args) {
        if(!System.out.println("Hello")){
            System.out.println("Hello");
        }else{
            System.out.println("World");
        }
    }

UPDATE: I think this works:

    public static void main(String args[]) {    
        if(System.out.append("Hello ")==null){
            System.out.print("Hello ");
        }else{
            System.out.println("World");
        } 
    }

In C:

main()
{   if(printf("Hello"),0)
         printf("Hello");
    else
       printf(" world!\n");
   getch();
}

Answer 1

Tadaaaa:

public static void main(String args[]) {    
    if(!new Object() {
        public boolean foo() {
            System.out.print("Hello ");
            return true;
        }
    }.foo()){
        System.out.println("Hello");
    }else{
        System.out.println("World");
    }
}

Answer 2

I can offer

if (System.out.printf("%s","Hello ") == null) {
    System.out.println("Hello");
} else {
    System.out.println("World");
}

Answer 3

It doesn't work because in Java if expects an expression of type boolean . System.out.println has no return type, it is void . That's why it doesn't work.

Answer 4

My 2 cents: None of the solutions, including the orginigal C solution actually execute both the ' if ' and the ' else '. All the solutions presented here execute and explicit printf("Hello") as part of the boolean expression in the condition . In all solutions, that condition is false and the else branch is then executed. But the actual if is not .

Answer 5

public class HelloWorld{
    public static void main(String[]args){
        if (new Object(){{ System.out.print("Hello "); }} == null){
            System.out.println("Hello");
        }else{
            System.out.println("World");
        }
    }
}

Answer 6

Switch on the contents of args and run the program twice with two different parameters.

Your program will either print out "Hello" or "World" unless you modify the input to println in addition to fixing your if() construct.

Answer 7

Consider the below code to execute both if-else block statements in C.

#include <stdio.h>
#include <stdbool.h>
int main()
{

  bool flag = false;
  if(flag)
  {
    printf("if block returns true-> now redirecting to else");
    goto el;
    i:
    printf(" redirected to if");
  }
  else
  {
    printf("if block returns false-> now redirecting to if");
    goto i;
    el:
    printf(" redirected to else");
  }
}

Just change the flag value in the above code. For example, if the flag value changed to true then first if block will execute and then else.

Answer 8

You could use append instead of println to determine if the write was successful:

if (System.out.append("Hello World" + System.getProperty("line.separator")) != null)
{
    // some code here
}

Answer 9

This can also be achieved using "printf" with out specifying the format. the code goes as below:

if (System.out.printf("Hello") == null) {
    System.out.print("Hello");
} else {
    System.out.println("World");
}

Answer 10

Check this one...

class Test {

    static boolean x = true;

    public static void main(String[] args) {
        ifAndElse();

    }

    public static void ifAndElse(){
        if (x) {
            System.out.println("hi");
            x = false;
            ifAndElse();
        } else {
            System.out.println("hello");
        }
    }
}

Answer 11

** Try this one **
class Test
{
    public static void main(String args[])
    {
        boolean one=true;
        for(int i=0;i<2;i++)
        {
        if(one)
        {
            System.out.print("Hello");
            one=false;  
        }   
        else

            System.out.println("World!");

        }       
    }
}`

Answer 12

public class Test {  

       public static void main(String args[]) {  

            if (args==null || new Test() {{Test.main(null);}}.equals(null)) {  
                     System.out.print("Hello ");
            } else {  
                     System.out.print("World！");  
            }  
       }  
}  

this can work, but a little bit complicate for understanding