JAVA TUTORIALS - Java - Methods
Java - Methods
ADVERTISEMENTS
Creating a Method:
modifier returnValueType methodName(list of parameters) { // Method body; }ADVERTISEMENTSExample:
/** Return the max between two numbers */ public static int max(int num1, int num2) { int result; if (num1 > num2) result = num1; else result = num2; return result; }ADVERTISEMENTSCalling a Method:
int larger = max(30, 40);
System.out.println("Welcome to Java!");Example:
public class TestMax { /** Main method */ public static void main(String[] args) { int i = 5; int j = 2; int k = max(i, j); System.out.println("The maximum between " + i + " and " + j + " is " + k); } /** Return the max between two numbers */ public static int max(int num1, int num2) { int result; if (num1 > num2) result = num1; else result = num2; return result; } }
The maximum between 5 and 2 is 5Example:
public class TestVoidMethod { public static void main(String[] args) { printGrade(78.5); } public static void printGrade(double score) { if (score >= 90.0) { System.out.println('A'); } else if (score >= 80.0) { System.out.println('B'); } else if (score >= 70.0) { System.out.println('C'); } else if (score >= 60.0) { System.out.println('D'); } else { System.out.println('F'); } } }
CPassing Parameters by Values:
public static void nPrintln(String message, int n) { for (int i = 0; i < n; i++) System.out.println(message); }Example:
public class TestPassByValue { public static void main(String[] args) { int num1 = 1; int num2 = 2; System.out.println("Before swap method, num1 is " + num1 + " and num2 is " + num2); // Invoke the swap method swap(num1, num2); System.out.println("After swap method, num1 is " + num1 + " and num2 is " + num2); } /** Method to swap two variables */ public static void swap(int n1, int n2) { System.out.println("\tInside the swap method"); System.out.println("\t\tBefore swapping n1 is " + n1 + " n2 is " + n2); // Swap n1 with n2 int temp = n1; n1 = n2; n2 = temp; System.out.println("\t\tAfter swapping n1 is " + n1 + " n2 is " + n2); } }Overloading Methods:
public static double max(double num1, double num2) { if (num1 > num2) return num1; else return num2; }Example:
public class CommandLine { public static void main(String args[]){ for(int i=0; i<args.length; i++){ System.out.println("args[" + i + "]: " + args[i]); } } }
java CommandLine this is a command line 200 -100
args[0]: this args[1]: is args[2]: a args[3]: command args[4]: line args[5]: 200 args[6]: -100Example:
// A simple constructor. class MyClass { int x; // Following is the constructor MyClass() { x = 10; } }
public class ConsDemo { public static void main(String args[]) { MyClass t1 = new MyClass(); MyClass t2 = new MyClass(); System.out.println(t1.x + " " + t2.x); } }Example:
// A simple constructor. class MyClass { int x; // Following is the constructor MyClass(int i ) { x = i; } }
public class ConsDemo { public static void main(String args[]) { MyClass t1 = new MyClass( 10 ); MyClass t2 = new MyClass( 20 ); System.out.println(t1.x + " " + t2.x); } }
10 20Variable Arguments(var-args):
typeName... parameterNameExample:
public class VarargsDemo { public static void main(String args[]) { // Call method with variable args printMax(34, 3, 3, 2, 56.5); printMax(new double[]{1, 2, 3}); } public static void printMax( double... numbers) { if (numbers.length == 0) { System.out.println("No argument passed"); return; } double result = numbers[0]; for (int i = 1; i < numbers.length; i++) if (numbers[i] > result) result = numbers[i]; System.out.println("The max value is " + result); } }
The max value is 56.5 The max value is 3.0The finalize( ) Method:
protected void finalize( ) { // finalization code here }