我是编程新手。我不确定如何将对象放置在框架的中央。这是我走了多远：
public class LetSee extends JPanel {
public void paintComponent(Graphics g) {
int row; // Row number, from 0 to 7
int col; // Column number, from 0 to 7
int x,y; // Top-left corner of square
for ( row = 0; row < 5; row++ ) {
for ( col = 0; col < 5; col++) {
x = col * 60;
y = row * 60;
if ( (row % 2) == (col % 2) )
g.drawRect(x, y, 60, 60);
else
g.drawRect(x, y, 60, 60);
}
} // end for row
}
}
public class LetSeeFrame extends JFrame {
public LetSeeFrame(){
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(1900, 1000);
setVisible(true);
LetSee let = new LetSee();
let.setLayout(new BorderLayout());
add(let,BorderLayout.CENTER);
setLocationRelativeTo(null);
}
public static void main(String[] args) {
LetSeeFrame l = new LetSeeFrame();
}
}
最佳答案
实际上，您的面板在框架中居中，但绘制的不是。
您应该使用width和height的JPanel将图形居中。
还要将大小和数字放入变量中，因此在代码中多次使用它们时，不容易出错。
最后就像@MadProgrammer在评论中所说的：
在进行任何自定义之前，请不要忘记调用super.paintComponent
绘画，如果不这样做，奇怪的事情就会开始做错。也
paintComponent不需要公开，没有人可以称呼它
直
import java.awt.Graphics;
import javax.swing.JPanel;
public class LetSee extends JPanel {
public void paintComponent(final Graphics g) {
super.paintComponent(g);
int row; // Row number, from 0 to 7
int col; // Column number, from 0 to 7
int x, y; // Top-left corner of square
int maxRows = 5;
int maxCols = 5;
int rectWidth = 60;
int rectHeight = 60;
int maxDrawWidth = rectWidth * maxCols;
int maxDrawHeight = rectHeight * maxRows;
// this is for centering :
int baseX = (getWidth() - maxDrawWidth) / 2;
int baseY = (getHeight() - maxDrawHeight) / 2;
for (row = 0; row < maxRows; row++) {
for (col = 0; col < maxCols; col++) {
x = col * rectWidth;
y = row * rectHeight;
if ((row % 2) == (col % 2)) {
g.drawRect(baseX + x, baseY + y, rectWidth, rectHeight);
} else {
g.drawRect(baseX + x, baseY + y, rectWidth, rectHeight);
}
}
} // end for row
}
}