在Java中解决空点异常

我越来越

**Exception in thread "main" java.lang.NullPointerException
    at sources.Own_gui.<init>(Own_gui.java:32)
    at sources.Maingui.main(Maingui.java:6)**

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我在netbeans中运行这个程序，它使用按钮进行输入。

问题在于这段代码

 buttonBoat[i][j]=new JButton();

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在使用buttonBoat数组之前，您没有初始化它。

声明和初始化是两件不同的事情。你在哪里初始化

按钮boat

数组？谢谢我已经解决了我的问题：）我忘了初始化数组：如果问题解决了，你可以接受这个答案来表示你已经找到了解决方案。这也会给你和回答问题的人一点声誉，我们将不胜感激。

package sources;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class playergui extends JFrame implements ActionListener
{
    JFrame framePlayer;
    JPanel panelHit,panelPlace,panelButtons,panelTable;
    JButton buttonBoat[][],buttonAttack[][];
    public playergui()
    {
        this.setLayout(new GridLayout(2,2));
        this.setTitle("Second Player");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setSize(500,500);
        this.setVisible(true);  
        panelButtons=new JPanel();
        panelHit=new JPanel();
        panelPlace=new JPanel();
        panelTable=new JPanel();
        panelHit.setLayout(new GridLayout(10,10));
        panelPlace.setLayout(new GridLayout(10,10));
        panelButtons.setLayout(new GridLayout(3,2));
        for(int i=0;i<10;i++)
    {
        for (int j=0;j<10;j++)
        {
            buttonBoat[i][j]=new JButton();
            panelPlace.add(buttonBoat[i][j]);
            buttonAttack[i][j]=new JButton();
            panelHit.add(buttonAttack[i][j]);
            buttonBoat[i][j].setActionCommand(i+","+j);
            buttonBoat[i][j].setBackground(Color.WHITE);
            buttonAttack[i][j].setBackground(Color.WHITE);
            buttonAttack[i][j].setActionCommand(i+","+j);
            buttonAttack[i][j].setEnabled(false);
            buttonBoat[i][j].addActionListener(this);
            buttonAttack[i][j].addActionListener(this);

        }
    }
        this.add(panelButtons);
        this.add(panelHit);
        this.add(panelPlace);
        this.add(panelTable);
    }
    @Override
    public void actionPerformed(ActionEvent e) {
    }

}

package sources;
public class Maingui
{
public static void main(String []args)
{
    Own_gui owg=new Own_gui();
    playergui pgi= new playergui();
}
}

 buttonBoat[i][j]=new JButton();