如何在Java中创建和使用函数[关闭]

I am new in Java universe. Back in my PHP days, I had a PHPFUNCTIONS.php file which contained collection of functions like:

    <?php
    // PHPFUNCTIONS.PHP................
    Function XYZ (var1, var2,..)
    {
     do this and that with var1, var2
     return val1;
    }
    //End XYZ function

    Function ABC (var3, var4,..)
    {
     do that and this with var3, var4
     return val2;
    }
    //End ABC function
    ...
    ..
    ?>

I could call any of these function from other .php files and pass vailables back and forth like:

    <?php
    // WORKTODO.PHP.....
    include "PHPFUNCTIONS.php";
    ....
    ....
    $A1B1=XYZ('abcd','ghij');
    .....
    <?

I have a hard time visualizing this concept in Java classes. How can I achive this in Java? Thanks

05-15-2015 4:67 pm
Okay. So, now I have:

    package org.tests;
    public class TestUtils {
        public static void main(String[] args) {
            double tempDegree=65.4;
            String lowerCase="lowercase";
            System.out.println("Fahrenheit=: "+ToFahrenheit(tempDegree));
            System.out.println();
            System.out.println("Upper=: "+ToUpper(lowerCase));
        }
    }

I get the following Error: TestUtils.java:6 error: cannot find symbol System.out.println(Fahrenheit=: "^ToFahrenheit

    package org.tests;
    public final class MyUtils {
    private MyUtils() {}
        public static Double ToFahrenheit(CelsiusTemp){
            Double CelsiusTemp;
        if (CelsiusTemp == null) {
                return null;
        }
        return (CelsiusTemp)*9/5 + 32;
        }
        public static String ToUpper(LowerWord){
            String LowerWord;
        if (LowerWord == null) {
                return null;
        }
        return LowerWord.toUpperCase();
        }
    }

I get the following Error: MyUtils.java:4: error: expected public static Double ToFahrenheit expected public static String ToUpper(LowerWord)^{

I am stuck... and not getting this concept.. any help?!

The common java idiom for such a usecase would be to have some utiliy class:

package org.something.myproject;

public final class MyProjectUtil { // Or a more meaningful name, hopefully {

    private MyProjectUtil() {}

    public static int abc (int a, int b...) {
        // do stuff
        return a;
    }

} 

and then use if from other classes. Possibly even use import static org.something.myproject.MyProjetUtil.abc; so you can call abc directly without prefixing it with MyProjectUtil.abc.