Relational and Conditional Operators

A relational operator compares two values and determines the relationship between them. For example, != returns true if the two operands are unequal. This table summarizes the relational operators:
Operator Use Returns true if
> op1 > op2 op1 is greater than op2
>= op1 >= op2 op1 is greater than or equal to op2
< op1 < op2 op1 is less than op2
<= op1 <= op2 op1 is less than or equal to op2
== op1 == op2 op1 and op2 are equal
!= op1 != op2 op1 and op2 are not equal

Following is an example, RelationalDemo, that defines three integer numbers and uses the relational operators to compare them. The relational operations are shown in red: 

public class RelationalDemo {
    public static void main(String[] args) {

        //a few numbers
        int i = 37;
        int j = 42;
        int k = 42;
        System.out.println("Variable values...");
        System.out.println("    i = " + i);
        System.out.println("    j = " + j);
        System.out.println("    k = " + k);

	//greater than
        System.out.println("Greater than...");
        System.out.println("    i > j = " + (i > j));	  //false
        System.out.println("    j > i = " + (j > i));     //true
        System.out.println("    k > j = " + (k > j));     //false, they are equal

	//greater than or equal to
        System.out.println("Greater than or equal to...");
        System.out.println("    i >= j = " + (i >= j));   //false
        System.out.println("    j >= i = " + (j >= i));   //true
        System.out.println("    k >= j = " + (k >= j));   //true

	//less than
        System.out.println("Less than...");
        System.out.println("    i < j = " + (i < j));     //true
        System.out.println("    j < i = " + (j < i));     //false
        System.out.println("    k < j = " + (k < j));     //false

	//less than or equal to
        System.out.println("Less than or equal to...");
        System.out.println("    i <= j = " + (i <= j));   //true
        System.out.println("    j <= i = " + (j <= i));   //false
        System.out.println("    k <= j = " + (k <= j));   //true

	//equal to
        System.out.println("Equal to...");
        System.out.println("    i == j = " + (i == j));   //false
        System.out.println("    k == j = " + (k == j));   //true

	//not equal to
        System.out.println("Not equal to...");
        System.out.println("    i != j = " + (i != j));   //true
        System.out.println("    k != j = " + (k != j));   //false

    }
}
Here's the output from this program: 
Variable values...
    i = 37
    j = 42
    k = 42
Greater than...
    i > j = false
    j > i = true
    k > j = false
Greater than or equal to...
    i >= j = false
    j >= i = true
    k >= j = true
Less than...
    i < j = true
    j < i = false
    k < j = false
Less than or equal to...
    i <= j = true
    j <= i = false
    k <= j = true
Equal to...
    i == j = false
    k == j = true
Not equal to...
    i != j = true
    k != j = false
Relational operators often are used with conditional operators to construct more complex decision-making expressions. The Java programming language supports six conditional operators-five binary and one unary--as shown in the following table.

 

Operator Use Returns true if
&& op1 && op2 op1 and op2 are both true, conditionally evaluates op2
|| op1 || op2 either op1 or op2 is true, conditionally evaluates op2
! ! op op is false
& op1 & op2 op1 and op2 are both true, always evaluates op1 and op2
| op1 | op2 either op1 or op2 is true, always evaluates op1 and op2
^ op1 ^ op2 if op1 and op2 are different--that is if one or the other of the operands is true but not both
The && operator will return true only if both operands are true. When both operands are boolean, the operator & performs the same operation as &&. However, & always evaluates both of its operands and returns true if both are true. Likewise, when the operands are boolean, | performs the same operation as ||. The | operator always evaluates both of its operands and returns true if at least one of its operands is true.