Suma con botones

Main. ClaseMatriz

public class Matriz {
public int numerofilas;
public int numerocolumnas;
public double [][]matriz;

public Matriz(){
}

public Matriz(int nf, int nc){
numerofilas = nf;
numerofolumnas = nc;
matriz = new double [numerofilas][numerocolumnas];

for(int i=0; i < numerofilas; i++)
for(int j=0; j < numerocolumnas; j++)
matriz[i][j]=0;
}

public Matriz suma(Matriz b){
Matriz resultado;

if((this.numerofilas == b.numerofilas)&& (this.numerocolumnas == b.numerocolumnas)){
resultado = new Matriz(this.numerofilas, this.numerocolumnas);
for(int i=0; i < this.numerofilas; i++)
for(int j=0; j < this.numerocolumnas; j++)
resultado.matriz[i][j] = this.matriz[i][j]+ b.matriz[i][j];
return resultado;
}
else
System.out.println("Error en las dimensiones de las matrices");
resultado=null;
return resultado;
}

public Matriz multiplicacion(Matriz b){
Matriz resultado;
if(this.numerofilas == b.numerocolumnas){
resultado=new Matriz(this.numerofilas,b.numerocolumnas);
for(int i=0; i < this.numerofilas; i++){
for(int j=0; j < b.numerocolumnas; j++){
for(int k=0; k < this.numerofilas; k++)
resultado.matriz[i][j] += (this.matriz[i][k]*b.matriz[k][j]);
}
}
return resultado;
}
else
System.out.println("Error en dimensiones de las matrices");
resultado = null;
return resultado;
}
public void leer(){
String aux;
for(int i=0; i < this.numerofilas; i++){
for(int j=0; j < this.numerocolumnas; j++){
aux = JOptionPane.showInputDialog(null,"Ingreso de valores","Ingrese el valor: "+(i+1)+","+(j+1),JOptionPane.DEFAULT_OPTION);
this.matriz[i][j]=Double.parseDouble(aux);
}
}
}

public String toString(){
String aux="\n[\n";
for(int i=0; i < numerofilas; i++){
for(int j=0; j < numerocolumnas; j++){
aux += matriz[i][j]+" ";
}
aux+="\n";
}
aux+= "]";
return aux;
}
}

Main.JavaApplet

public class NewJApplet extends javax.swing.JApplet {

/** Initializes the applet NewJApplet */
public void init() {
try {
java.awt.EventQueue.invokeAndWait(new Runnable() {
public void run() {
initComponents();
}
});
} catch (Exception ex) {
ex.printStackTrace();
}
}

/** This method is called from within the init() method to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
//
private void initComponents() {

jPanel1 = new javax.swing.JPanel();
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jButton1 = new javax.swing.JButton();
jTextField1 = new javax.swing.JTextField();
jTextField2 = new javax.swing.JTextField();
jScrollPane1 = new javax.swing.JScrollPane();
jTextArea1 = new javax.swing.JTextArea();
jLabel4 = new javax.swing.JLabel();
jButton2 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
jButton4 = new javax.swing.JButton();

jLabel1.setBackground(new java.awt.Color(255, 0, 255));
jLabel1.setFont(new java.awt.Font("Bradley Hand ITC", 3, 24));
jLabel1.setForeground(new java.awt.Color(255, 102, 204));
jLabel1.setText("CLASE MATRIZ");

jLabel2.setBackground(new java.awt.Color(255, 51, 51));
jLabel2.setText("Numero de filas");

jLabel3.setText("Numero de columnas");

jButton1.setText("leer matriz 1");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});

jTextField1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField1ActionPerformed(evt);
}
});

jTextArea1.setColumns(20);
jTextArea1.setRows(5);
jScrollPane1.setViewportView(jTextArea1);

jLabel4.setText("resultados");

jButton2.setText("imprimir");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});

jButton3.setText("leer matriz 2");
jButton3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton3ActionPerformed(evt);
}
});

jButton4.setText("sumar");
jButton4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton4ActionPerformed(evt);
}
});

javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addContainerGap(108, Short.MAX_VALUE)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 200, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(112, 112, 112))
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(23, 23, 23)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel2)
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jButton1)
.addComponent(jButton4)
.addComponent(jButton3)
.addComponent(jButton2))
.addGap(53, 53, 53)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(jTextField2, javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jTextField1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 89, Short.MAX_VALUE))
.addComponent(jLabel4))
.addContainerGap(77, Short.MAX_VALUE))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 83, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(14, 14, 14)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel2)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3))
.addGap(21, 21, 21)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jButton1)
.addComponent(jLabel4))
.addGap(11, 11, 11)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(jButton3)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jButton4)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jButton2)))
.addContainerGap(31, Short.MAX_VALUE))
);

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
}//

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String aux = jTextField1.getText();
nf = Integer.parseInt(aux);
aux = jTextField2.getText();
nc = Integer.parseInt(aux);//metodo para cambiar de string a entero
m = new Matriz(nf,nc);
}

private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
jTextArea1.setText(m.toString());
jTextArea1.setText(n.toString());
jTextArea1.setText(r.toString());
}

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String aux = jTextField1.getText();
nf = Integer.parseInt(aux);
aux = jTextField2.getText();
nc = Integer.parseInt(aux);//metodo para cambiar de string a entero
n = new Matriz(nf,nc);
n.leer();
}

private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
r = new Matriz(nf,nc);
r = m.suma(n);
}


// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JButton jButton4;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JPanel jPanel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTextArea jTextArea1;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
// End of variables declaration
public int nf;
public int nc;
public Matriz m;
public Matriz n;
public Matriz r;
}