Question

求教java大神，怎么在文本框输入之后，敲回车在标签上显示，如图片所示

源代码package Lottery;import java.awt.BorderLayout;import java.awt.Color;import java.awt.FlowLayout;import java.awt.Font;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.*;import javax.swing.border.Border;public class cp extends JFrame { private String str; private JPanel p1=new JPanel(); private JPanel p2=new JPanel(); private JPanel p3=new JPanel(); private JPanel p4=new JPanel(); private JPanel p5=new JPanel(); private JPanel p6=new JPanel(); private JPanel p7=new JPanel(); private JLabel l1=new JLabel("35选7",JLabel.LEFT); private JLabel l2=new JLabel("输入选号："); private JLabel l3=new JLabel("当前选号："); private JLabel l4=new JLabel(str); private JTextField jtf=new JTextField(5); private JTextArea jta=new JTextArea(5,20); private JButton b1=new JButton("添加本组号码"); JButton b2=new JButton("验证并保存到文件"); public cp(){ { p1.setBorder(BorderFactory.createEtchedBorder()); p5.setBorder(BorderFactory.createEtchedBorder()); p6.setBorder(BorderFactory.createEtchedBorder()); l1.setFont(new Font(null,Font.BOLD,20)); p1.setLayout(new FlowLayout(FlowLayout.LEFT)); p1.add(l1); p2.setLayout(new FlowLayout(FlowLayout.LEFT)); p2.add(l2);p2.add(jtf); jtf.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { str=jtf.getText(); l4 = new JLabel(str); } }); p3.setLayout(new FlowLayout(FlowLayout.LEFT)); p3.add(l3);p3.add(l4); p4.setLayout(new FlowLayout(FlowLayout.LEFT)); p4.add(b1); p5.setLayout(new GridLayout(3,1)); p5.add(p2);p5.add(p3);p5.add(p4); p6.setLayout(new FlowLayout(FlowLayout.LEFT)); p6.add(jta);p6.add(b2); p7.setLayout(new GridLayout(2,1)); p7.add(p5); p7.add(p6); add(p1,BorderLayout.NORTH); add(p7,BorderLayout.CENTER); } } public static void main(String[] args) { cp frame=new cp(); frame.setTitle("Lottery"); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(400,300); frame.setVisible(true); }}

Answer 1

要在文本框输入之后敲回车在标签中显示，需要给文本框加上ActionListener监听器，并重写其

actionPerformed方法，完整的Java程序如下：(改动的地方见注释,当"输入选号"为空时回车,会把"当前选号"置为空)

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;//这里导入监听接口
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
public class CCG extends JFrame implements ActionListener{//这里加监听接口
 JLabel jl1=new JLabel("35选7",JLabel.LEFT);
 JLabel jl2=new JLabel("输入选号：");
 JLabel jl3=new JLabel("当前选号：");
 JLabel jl4=new JLabel();    //这里改一下
 JTextField jtf=new JTextField(5);
 JTextArea jta=new JTextArea(5,20);
 JButton jb1=new JButton("添加本组号码");
 JButton jb2=new JButton("验证并保存到文件");
 JPanel jp1=new JPanel();
 JPanel jp2=new JPanel();
 JPanel jp3=new JPanel();
 JPanel jp4=new JPanel();
 JPanel jp5=new JPanel();
 JPanel jp6=new JPanel();
 JPanel jp7=new JPanel();
 CCG(){
  super("Lottery");
  jtf.addActionListener(this);   //这里加监听器
  jl1.setFont(new Font(null,Font.BOLD,20));
  jp1.setLayout(new FlowLayout(FlowLayout.LEFT));
  jp1.add(jl1);
  jp1.setBorder(BorderFactory.createEtchedBorder ());
  jp4.setLayout(new FlowLayout(FlowLayout.LEFT));
  jp4.add(jl2);jp4.add(jtf);
  jp5.setLayout(new FlowLayout(FlowLayout.LEFT));
  jp5.add(jl3);jp5.add(jl4);
  jp6.setLayout(new FlowLayout(FlowLayout.LEFT));
  jp6.add(jb1);
  jp2.setLayout(new GridLayout(3,1));
  jp2.add(jp4);jp2.add(jp5);jp2.add(jp6);
  jp2.setBorder(BorderFactory.createEtchedBorder ());
  jp3.setLayout(new FlowLayout(FlowLayout.LEFT));
  jp3.add(jta);jp3.add(jb2);
  jp3.setBorder(BorderFactory.createEtchedBorder ());
  jp7.setLayout(new GridLayout(2,1));
  jp7.add(jp2);
  jp7.add(jp3);
  add(jp1,BorderLayout.NORTH);
  add(jp7,BorderLayout.CENTER);
  setSize(400, 300);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setLocationRelativeTo(null);
  setVisible(true);
 }
 @Override
 public void actionPerformed(ActionEvent ae) {//这里加监听函数
  if(ae.getSource()==jtf){
   if(jtf.getText().equals("")){
    jl4.setText("");
   }else{
    if(jl4.getText().equals("")){
     jl4.setText(jtf.getText());
    }else{
     jl4.setText(jl4.getText()+","+jtf.getText());
    }
   }
  }
 }
 public static void main(String[] args) {
  new CCG();
 }
}

运行结果：

追问

如果是要把文本框里的数据保存在数组中呢，然后对数组排序，再把排序后的在标签中显示，谢谢大神

追答

@Override

 public void actionPerformed(ActionEvent ae) {//这里加监听函数

  if(ae.getSource()==jtf){

   if(jtf.getText().equals("")){

    jl4.setText("");

   }else{

    if(jl4.getText().equals("")){

     jl4.setText(jtf.getText());

    }else{

     String[]a=(jl4.getText()+","+jtf.getText()).split(",");

     int []b=new int[a.length];

     for(int i=0;i<a.length;i++){

      b[i]=Integer.parseInt(a[i].trim());

     }

     Arrays.sort(b);

     String tmp=Arrays.toString(b);

     String s=tmp.substring(1,tmp.length()-1);

     jl4.setText(s);

    }

   }

  }

 }

Answer 2

输入选号的input标签 看看有没有onchange事件，在onchange事件中，将你这个input的值，设置到当前选号的label中，先找到label，再使用innerHTML属性

追问

看不懂啊

追答

日你一脸：前台代码贴出来，不要图片

Answer 3

jtf.addActionListener(new ActionListener() {
 public void actionPerformed(ActionEvent e) {
  str=jtf.getText();
  // l4 = new JLabel(str);// 这里错了，不能每次去new一个
  l4.setText(str);
 }
});

追问

是这样的，我要在文本框里输入数据，敲回车后保存在数组中并显示在标签中，假设有5个数据
，敲一次后在标签中加一个，怎么实现啊

追答

l4.setText(l4.getText()/*获取标签原有的*/+"，"/*分隔符*/+ str/*追加新的*/);