Tricky Examples 1

1. Assignment operator always returns the value which is assigned. Here I am giving some examples.
public class Test
{
    public static void main(String[] args) 
    {
    boolean a = true;
    float b = 0.0f;
    double c = 0.0;
    int d = 0;
   
    if(a = false)
    {
    System.out.print("\nThis is will not executed");
    }//if
    else
    {
    System.out.print("\nThis is false : " + (a = false));
    }//else
   
    if(a = true)
    {
    System.out.print("\nThis is will executed now because (a = true) = " + (a = true));
    }//if
    else
    {
    System.out.print("\nThis is will not executed");
    }//else
    /* In java if(condition) statement will always need boolean value
    * so following all code will fail to compile
    * if(b = 2.3)
    * if(c = 4.3)
    * if(d = 3)
    * Lets see what will be return value for these
    */
    System.out.print("\n(b = 2.3) = " + (b = 2.3f));
    System.out.print("\n(c = 4.3) = " + (c = 4.3));
    System.out.print("\n(d = 3) = " + (d = 3));
    }//PSVM
}//class Test

2. For down cast you will need explicit casting.
public class Test
{
    public static void main(String [] args) 
    {
    byte b = 10;
    short s = 20;
    int i = 30;
    float f = 40f;
    double d = 50;
    // Here are few valid assignments
    d = f;
    f = i;
    i = s;
    s = b;
    //Here are few invalid assignments
    b = s;
    s = i;
    i = f;
    f = d;
    //To make this working you have to cast explicitly
    b = (byte)s;
    s = (short)i;
    i = (int)f;
    f = (float)d;
    }//PSVM
}//class Test

3. Only byte, short, int, char, String and enum is allowed in switch case. Here I am giving example.
public class Test 
{
    public static void main(String args[]) 
    { 
    String f ="0";
    switch (f) 
    {
    }
    int f1 = 0;
    switch (f1/2) 
    {
    }
    byte f2 = 0;
    switch (f2 + 3) 
    {
    }
    short f3 = 0;
    switch (f3) 
    {
    }
    char f4 = '0';
    switch (f4) 
    {
    }
    /*
    It will fail for float, double, long    
    float f4 = 2.3f;
    switch(f4)
    {
    }
    */
    } 
}