Java Coded Window Functions:

 
/* Rectangular Window Function */
public float Rewt(float x, int nn){
float bl,a0;
a0=(float)1.0;
bl=(float)a0;
return(bl);}

/* Hamming Window Function */
public float Hamwt(float x, int nn){
float bl,a0,a1,a2,pi;
pi= (float)Math.PI;
a0=(float)0.54;
a1=(float)0.46;
a2=(float)0.0;
bl=(float)(a0+a1*(float)Math.cos(2*pi*(x-nn/2)/nn)+a2*(float)Math.cos(2*2*pi*(x-nn/2)/nn));
return(bl);}

/* Hanning Window Function */
public float Hanwt(float x, int nn){
float bl,a0,a1,a2,pi;
pi= (float)Math.PI;
a0=(float)0.5;
a1=(float)0.5;
a2=(float)0.0;
bl=(float)(a0+a1*(float)Math.cos(2*pi*(x-nn/2)/nn)+a2*(float)Math.cos(2*2*pi*(x-nn/2)/nn));
return(bl);}

/* Flat Top Window Function */
public float FTwt(float x, int nn){
float bl,a0,a1,a2,pi;
pi= (float)Math.PI;
a0=(float)0.2810639;
a1=(float)0.5208972;
a2=(float)0.1980399;
bl=(float)(a0+a1*(float)Math.cos(2*pi*(x-(float)nn/2)/(float)nn) +a2*(float)Math.cos(2*2*pi*(x-(float)nn/2)/(float)nn));
return(bl);}

/* Lanczos Window Function */
public float Lawt(float x, int nn){
float bl,a0;
a0=2*(x-nn/2)*(float)Math.PI/(nn+1);
if(a0==0)bl=1;
else bl=(float)Math.sin(a0)/a0;
if(bl<0)bl=0;
return(bl);}

/* Triangular Window Function */
public float Trwt(float x, int nn){
float bl,a0;
if(x<(float)nn/2)bl=2*x/(float)nn;
else bl=2*((float)nn-(float)x)/(float)nn;
return(bl);}

/*Chebyshev Inverse Fourier Function */
public double Tch(double x,int n){
double tch;
if(Math.abs(x)>1.0)tch=Cosh((double)n*aCosh(x));
else tch=Math.cos((double)n*Math.acos(x));
return(tch);}

/* Kaiser Window Function */
public float Kawt(float x, int nn, float a){
float bl,a0;
a0=(float)Math.PI*a;
if(x<nn+1)bl=(float)(In(0,a0*(float)Math.sqrt(1-(2*(x)/nn-1)*(2*(x)/nn-1)))/In(0,a0));
else bl=0;
return(bl);}

/* Gaussian Window Function */
public float Gawt(float x, int nn, float a){
float bl,a0;
a0=(float)a;
bl=(float)Math.exp(-0.5*(2*a0*(x-nn/2)/nn)*(2*a0*(x-nn/2)/nn));
return(bl);}
/* Riesz Window Function */
public float Riwt(float x, int nn){
float bl,a0;
a0=2*(x-nn/2)/(nn+1);
bl=1-a0*a0;
return(bl);}

/* Blackman Window Function */
public float Blwt(float x, int nn){
float bl,a0,a1,a2,pi;
pi= (float)Math.PI;
a0=(float)0.42;
a1=(float)-0.5;
a2=(float)0.08;
bl=(float)(a0+a1*(float)Math.cos(2*pi*(x)/nn)+a2*(float)Math.cos(2*2*pi*(x)/nn));
return(bl);}

/* Blackman-Harris 3 Window Function */
public float BH3wt(float x, int nn){
float bl,a0,a1,a2,pi;
pi= (float)Math.PI;
a0=(float)0.44951;
a1=(float)-0.49364;
a2=(float)0.05677;
bl=(float)(a0+a1*(float)Math.cos(2*pi*(x)/nn)+a2*(float)Math.cos(2*2*pi*(x)/nn));
return(bl);}

/* Blackman-Harris 4 Window Function */
public float BH4wt(float x, int nn){
float bl,a0,a1,a2,a3,pi;
pi= (float)Math.PI;
a0=(float)0.40217;
a1=(float)-0.49703;
a2=(float)0.09892;
a3=(float)-0.001188;
bl=(float)(a0+a1*(float)Math.cos(2*pi*(x)/nn)+a2*(float)Math.cos(2*2*pi*(x)/nn) +a3*(float)Math.cos(2*3*pi*(x)/nn));
return(bl);}