collision detection - Making MineCraft In 2D

I am making a 2D game that is based on Minecraft. I made the terrain but I just don't know how to do the collision between the player. I tied to draw the rectangles with a for loop and detect collision between the player player and the rectangles but when I run it it only detects collision between the last rectangle on the map and the player. Please help.

This is my code.

    import java.awt.Graphics;
    import java.awt.Rectangle;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.awt.event.KeyEvent;
    import java.awt.event.KeyListener;

    import java.awt.image.BufferedImage;
    import java.io.IOException;

    import javax.imageio.ImageIO;
    import javax.swing.ImageIcon;
    import javax.swing.JPanel;

    public class Gameplay extends JPanel implements ActionListener, KeyListener{
private BufferedImage player;
private BufferedImage block;

private BufferedImage dbImage;
private ImageIcon player2;
private Graphics dbg;
private int x = 0;
private int y = 0;
private double velX = 5.0f;
private double velY = 5.0f;
public Rectangle rectangle;
public Rectangle rectangle2;
private int[] xb = {0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650};

private int[] yb = {0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650};
//
public Gameplay(){
    addKeyListener(this);
    setFocusable(true);
}

public void paint(Graphics g){
    dbImage = (BufferedImage) createImage(getWidth(), getHeight());
    dbg = dbImage.getGraphics();

    paintComponent(dbg);
    g.drawImage(dbImage, 0, 0, this);
    repaint();
}
public void paintComponent(Graphics g){
    try {
        player = ImageIO.read(getClass().getResource("Player.png"));
        block = ImageIO.read(getClass().getResource("Grass.png"));
    } catch (IOException e) {
        // TODO Auto-generated catch block

        e.printStackTrace();
    }
    drawBlock(g);
    g.drawImage(player, x, y, this);
    rectangle2 = new Rectangle(x, y, 50, 50);
    if(rectangle2.intersects(rectangle)){
        System.out.println("Hello");
    }
}


public void drawBlock(Graphics g){
    for(int first = 0; first < 10; first++){
        for(int second = 0; second < 10; second++){
            g.drawImage(block, xb[first], yb[second], this);
            rectangle = new Rectangle(xb[first], yb[second], 50, 50);
        }
    }

}


@Override
public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub

}

@Override
public void keyPressed(KeyEvent e) {
    if(e.getKeyCode() == KeyEvent.VK_UP){
        y += -velY;

    }
    else if(e.getKeyCode() == KeyEvent.VK_DOWN){
        y += velY;
    }
    else if(e.getKeyCode() == KeyEvent.VK_LEFT){
        x += -velX;
    }
    else if(e.getKeyCode() == KeyEvent.VK_RIGHT){
        x += velX;
    }



}

@Override
public void keyReleased(KeyEvent e) {
    // TODO Auto-generated method stub

}


@Override
public void keyTyped(KeyEvent e) {
    // TODO Auto-generated method stub

}
     }