Swing —— 限制JTextArea只能输入浮点数
下面是示例代码：?
[复制源代码]
class JTextFieldFilterextends PlainDocument {
public static final StringFLOAT = "0123456789.";
protected String acceptedChars = null;
protected boolean negativeAccepted =false;
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public JTextFieldFilter() {
this(FLOAT);
}
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public JTextFieldFilter(String acceptedChars) {
this.acceptedChars = acceptedChars;
}
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/**
?*设置是否接受负号
?*
?* @param negativeAccepted
?*???????????是否接受负号
?*/
public void setNegativeAccepted(boolean negativeAccepted) {
if (acceptedChars.equals(FLOAT)) {
this.negativeAccepted = negativeAccepted;
acceptedChars += "-";
}
}
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public void insertString(int offset, String str, AttributeSet attr)
throws BadLocationException {
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//判断输入的是否为允许的字符
for (int i = 0; i < str.length(); i++) {
if (!acceptedChars.contains(str)) {
return;
}
}
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//判断当前输入的是否为".",如果有了再判断前面有没有输入过
if (acceptedChars.equals(FLOAT)
|| (acceptedChars.equals(FLOAT +"-") && negativeAccepted)) {
if (str.contains(".")) {
if (getText(0, getLength()).contains(".")) {
return;
}
}
}
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//判断如果支持负数,那么负号(-)必须在第一位
if (negativeAccepted) {
if (str.indexOf("-") != 0 || offset != 0) {
return;
}
}
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super.insertString(offset, str, attr);
}
}
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publicclass Main extends JFrame {
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public static void main(String[] argv)throws Exception {
new Main();
}
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public Main() {
setLayout(new FlowLayout());
JLabel lb = new JLabel("only float");
JTextField tf = new JTextField(10);
getContentPane().add(lb);
getContentPane().add(tf);
tf.setDocument(new JTextFieldFilter(JTextFieldFilter.FLOAT));
setSize(300, 300);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
