文本编辑器

 运行结果如下：

字符串查找：

保存：

 查找字符数量及替换等其余功能：

import java.awt.BorderLayout;
import java.io.*;
import javax.swing.*;
public class A extends JFrame{
    private static final long serialVersionUID = 1L;
    JTextArea jta;
    JButton jbt,SearchJBT,SearchCharJBT, ReplaceJBT,SearchNums;
    JFileChooser fileChooser = new JFileChooser();
    public A(){
        super("文本编辑器");
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setSize(500,700 );
        this.setLayout(new BorderLayout());
        this.setLocation(500,300);
        this.setResizable(false);
        _initTextArea();
        _initButton();
        _initLable();
    }
    private void _initTextArea(){
        JPanel jp = new JPanel();
        jta= new JTextArea(30,40);
        jp.add(jta);
        this.add(jp,BorderLayout.CENTER);
    }
    private void _initButton(){
        JPanel jp = new JPanel();
        jbt=new JButton("保存");
        jbt.addActionListener((param)->saveDataToFile(jta.getText(),"my.txt"));
        jp.add(jbt);
        SearchJBT = new JButton("查找");
        SearchJBT.addActionListener((param)->{
            String inputContent = JOptionPane.showInputDialog(null,"输入要找的字符串:","");
            int res = _search(inputContent);
           if(res>-1){JOptionPane.showMessageDialog( null,"字符串开始在"+(int)(res+1)+"的位置","字符串找到了",JOptionPane.INFORMATION_MESSAGE);}else{
               JOptionPane.showMessageDialog(null,"没找到","字符串",JOptionPane.INFORMATION_MESSAGE
               );
           }
        });
        jp.add(SearchJBT);
        SearchCharJBT = new JButton("有多少个字符");
        SearchCharJBT.addActionListener((param)->{
            JOptionPane.showMessageDialog(null,"一共有"+_HowManyChar()+"个字符","QAQ",JOptionPane.INFORMATION_MESSAGE);
        });
        jp.add(SearchCharJBT);
        ReplaceJBT = new JButton("替换");
        ReplaceJBT.addActionListener((param)->{
            String str1 = JOptionPane.showInputDialog(null,"输入要替换的字符串:","");
            String str2 = JOptionPane.showInputDialog(null,"你想换成什么:","");
            if(str1!=null&&str2!=null){
                _replaces(str1, str2);
            }
        });
        jp.add(ReplaceJBT);
        SearchNums = new JButton("有多少数字");
        SearchNums.addActionListener((param)->{
            JOptionPane.showMessageDialog(null,"一共有"+_HowManyNums()+"个数字","QAQ",JOptionPane.INFORMATION_MESSAGE);
        });
        jp.add(SearchNums);
        this.add(jp,BorderLayout.NORTH);
    }
    private void saveDataToFile(String data, String fileName) {
        fileChooser.setSelectedFile(new File(fileName));
        fileChooser.showSaveDialog(null);
        String filePath = fileChooser.getSelectedFile().toString();
        try {
            FileWriter writer = new FileWriter(filePath);
            writer.append(data);
            writer.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private void _initLable(){
        JPanel jp = new JPanel();
        jp.setLayout(new BoxLayout(jp,BoxLayout.Y_AXIS));
        for(int i=1;i<30;i++){
            jp.add(new JLabel(i+""));
        }
        this.add(jp,BorderLayout.WEST);
    }
    private int _search(String str){
        return jta.getText().indexOf(str);
    }
    private int _HowManyChar(){
        return jta.getText().length();
    }
    private void _replaces(String str1,String str2){
        String str = jta.getText();
        str = str.replaceAll(str1,str2);
        jta.setText(str);
    }
    private int _HowManyNums(){
        String str = jta.getText();
        int res = 0;
        for(int i=0;i<str.length();i++){
            if(str.charAt(i)>='0'&&str.charAt(i)<='9') res++;
        }
        return res;
    }
    public static void main(String[] args) {
        new A();
    }
}