讓java顯示超過1個.add（）

Question

我已經開始學習基本的Java，並且想重寫我曾經用PHP寫過的遊戲地圖生成器。我有一部分工作正常（這只是一個開始），但每當我想顯示2件事情（使用.add（））時，它只會顯示其中的一個。這是我的代碼

public static void main(String[] args) { 
    JFrame m1 = new JFrame(); 
    Container con = m1.getContentPane(); 
    Color c = new Color(16, 174, 0); 
    con.setBackground(c); 
    m1.setSize(mapWidth, mapHeight); 
    m1.setTitle("ThomasMosey's Map Generator"); // Window Title 
    m1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    m1.add(new User()); 
    m1.add(new Grid()); 
    m1.setVisible(true); 
} 

它只是代碼的一部分，但我想知道是否我在.add那裏做了任何錯誤。

預先感謝您。

---

這是完整的代碼;

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Container; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.RenderingHints; 
import javax.swing.JComponent; 
import javax.swing.JFrame; 

public class Map extends JFrame { 
    public static int mapWidth = 576; // The Map's Width 
    public static int mapHeight = 598; // The Map's Height 
    public static int userX = 1; 
    public static int userY = 1; 
    private static final long serialVersionUID = 1L; 
    public static void main(String[] args) { 
     JFrame m1 = new JFrame(); 
     Container con = m1.getContentPane(); 
     Color c = new Color(16, 174, 0); 
     con.setBackground(c); 
     m1.setSize(mapWidth, mapHeight); 
     m1.setTitle("ThomasMosey's Map Generator"); // Window Title 
     m1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     con.add(new User(), BorderLayout.NORTH); 
     con.add(new Grid(), BorderLayout.CENTER); 
     m1.setVisible(true); 
    } 
} 
// The Grid system 
class Grid extends JComponent { 
    private static final long serialVersionUID = 1L; 
    public void paint(Graphics g) { 
     Graphics2D g2 = (Graphics2D) g; 
     g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
     Color gridColor = new Color(0, 84, 12); 
     g2.setColor(gridColor); 
     int i; 
     int i2; 
     for(i = 50; i <= Map.mapWidth; i += 51) { 
      g2.drawLine(0, i, Map.mapWidth, i); 
     } 
     for(i2 = 50; i2 <= Map.mapHeight; i2 += 51) { 
      g2.drawLine(i2, 0, i2, Map.mapHeight); 
     } 
    } 
} 
// Drawing the Grid but lower down to give a significant difference to check whether or not it's actually drawing on the JFrame 
class User extends JComponent { 
    private static final long serialVersionUID = 1L; 
    public void paint(Graphics g2) { 
     Graphics2D g22 = (Graphics2D) g2; 
     g22.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
     Color gridColor = new Color(0, 84, 12); 
     g22.setColor(gridColor); 
     int i22; 
     for(i22 = 50; i22 <= 6000; i22 += 53) { 
      g22.drawLine(0, i22, Map.mapWidth, i22+1); 
     } 
    } 
} 

Answer 1

1. 的內容窗格的默認佈局是BorderLayout。
2. 將組件添加到不受約束的邊框佈局，並以CENTER結尾。
3. 只有一個組件可以出現在邊框佈局的每個部分中。

---

那麼試試這個，而不是..這個問題的

m1.add(new User(), BorderLayout.NORTH); 
m1.add(new Grid(), BorderLayout.CENTER); 

---

部分原因是，自定義組件具有0x0到默認首選尺寸。試試這個變種。

import java.awt.*; 
import javax.swing.*; 

public class Map extends JFrame { 
    public static int mapWidth = 576; // The Map's Width 
    public static int mapHeight = 598; // The Map's Height 
    public static int userX = 1; 
    public static int userY = 1; 
    private static final long serialVersionUID = 1L; 
    public static void main(String[] args) { 
     JFrame m1 = new JFrame(); 
     Container con = m1.getContentPane(); 
     Color c = new Color(16, 174, 0); 
     con.setBackground(c); 
     // bad form - pack() instead 
     //m1.setSize(mapWidth, mapHeight); 
     m1.setTitle("ThomasMosey's Map Generator"); // Window Title 
     m1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     User user = new User(); 
     user.setPreferredSize(new Dimension(300,300)); 
     con.add(user, BorderLayout.NORTH); 
     Grid grid = new Grid(); 
     grid.setPreferredSize(new Dimension(600,600)); 
     con.add(grid, BorderLayout.CENTER); 
     m1.pack(); 
     m1.setVisible(true); 
    } 
} 
// The Grid system 
class Grid extends JComponent { 
    private static final long serialVersionUID = 1L; 
    public void paintComponent(Graphics g) { 
     Graphics2D g2 = (Graphics2D) g; 
     g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
     Color gridColor = new Color(0, 84, 12); 
     g2.setColor(gridColor); 
     int i; 
     int i2; 
     for(i = 50; i <= Map.mapWidth; i += 51) { 
      g2.drawLine(0, i, Map.mapWidth, i); 
     } 
     for(i2 = 50; i2 <= Map.mapHeight; i2 += 51) { 
      g2.drawLine(i2, 0, i2, Map.mapHeight); 
     } 
    } 
} 
// Drawing the Grid but lower down to give a significant difference to check whether or not it's actually drawing on the JFrame 
class User extends JComponent { 
    private static final long serialVersionUID = 1L; 
    public void paintComponent(Graphics g2) { 
     Graphics2D g22 = (Graphics2D) g2; 
     g22.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
     Color gridColor = new Color(0, 84, 12); 
     g22.setColor(gridColor); 
     int i22; 
     for(i22 = 50; i22 <= 6000; i22 += 53) { 
      g22.drawLine(0, i22, Map.mapWidth, i22+1); 
     } 
    } 
} 

Answer 2

AFAIR，內容窗格baqcking默認情況下，JFrame只接受單個子項。你將不得不 組，並配置一些佈局有一個以上的孩子

Answer 3

的JFrame當前佈局是BorderLayout和你是在中心添加這兩種成分。嘗試改變佈局。

Container con = m1.getContentPane(); 
con.setLayout(new FlowLayout()); 

或

m1.add(new User(),BorderLayout.NORTH); 
m1.add(new Grid(),BorderLayout.CENTER); 

編輯：你來覆蓋用戶有必要對setPreferredSize（）方法。

class User extends JComponent { 
    public java.awt.Dimension getPreferredSize() { 
    return new java.awt.Dimension(100,100); 
    } 
}