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📜  Java Swing-JTextField

📅  最后修改于: 2020-09-29 10:00:20             🧑  作者: Mango

Java JTextField

JTextField类的对象是一个文本组件，允许编辑单行文本。它继承了JTextComponent类。

JTextField类声明

我们来看一下javax.swing.JTextField类的声明。

public class JTextField extends JTextComponent implements SwingConstants

常用的构造函数：

Constructor Description
JTextField() Creates a new TextField
JTextField(String text) Creates a new TextField initialized with the specified text.
JTextField(String text, int columns) Creates a new TextField initialized with the specified text and columns.
JTextField(int columns) Creates a new empty TextField with the specified number of columns.

常用方法：

Methods Description
void addActionListener(ActionListener l) It is used to add the specified action listener to receive action events from this textfield.
Action getAction() It returns the currently set Action for this ActionEvent source, or null if no Action is set.
void setFont(Font f) It is used to set the current font.
void removeActionListener(ActionListener l) It is used to remove the specified action listener so that it no longer receives action events from this textfield.

Java JTextField示例

import javax.swing.*;
class TextFieldExample
{
public static void main(String args[])
    {
    JFrame f= new JFrame("TextField Example");
    JTextField t1,t2;
    t1=new JTextField("Welcome to Javatpoint.");
    t1.setBounds(50,100, 200,30);
    t2=new JTextField("AWT Tutorial");
    t2.setBounds(50,150, 200,30);
    f.add(t1); f.add(t2);
    f.setSize(400,400);
    f.setLayout(null);
    f.setVisible(true);
    }
    }

输出：

带有ActionListener的Java JTextField示例

import javax.swing.*;
import java.awt.event.*;
public class TextFieldExample implements ActionListener{
JTextField tf1,tf2,tf3;
JButton b1,b2;
TextFieldExample(){
    JFrame f= new JFrame();
tf1=new JTextField();
tf1.setBounds(50,50,150,20);
tf2=new JTextField();
tf2.setBounds(50,100,150,20);
tf3=new JTextField();
tf3.setBounds(50,150,150,20);
tf3.setEditable(false);
b1=new JButton("+");
b1.setBounds(50,200,50,50);
b2=new JButton("-");
b2.setBounds(120,200,50,50);
b1.addActionListener(this);
b2.addActionListener(this);
f.add(tf1);f.add(tf2);f.add(tf3);f.add(b1);f.add(b2);
f.setSize(300,300);
f.setLayout(null);
f.setVisible(true);
}
public void actionPerformed(ActionEvent e) {
String s1=tf1.getText();
String s2=tf2.getText();
int a=Integer.parseInt(s1);
int b=Integer.parseInt(s2);
int c=0;
if(e.getSource()==b1){
c=a+b;
}else if(e.getSource()==b2){
c=a-b;
}
String result=String.valueOf(c);
tf3.setText(result);
}
public static void main(String[] args) {
new TextFieldExample();
} }

输出：