setCharAt for JLabel

Question

我正在尝试用可以与JLabel一起使用的东西替换setCharAt ...我一直在oracle doc寻找解决方案。我不知道我是在寻找错误的东西，还是只是不存在......如果它不存在我怎么能解决这个问题呢？我理解我的命名惯例是关闭的，并将尽快更改它们......

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

import javax.swing.*;



public class HangmanPanel extends JPanel {
    static Boolean FOUND;
    private static final long serialVersionUID = -5793357804828609325L;

    public static String answerKey() {
        //get random array element
        String array[] = new String[10];
        array[0] = "hamlet";
        array[1] = "mysts of avalon";
        array[2] = "the iliad";
        array[3] = "tales from edger allan poe";
        array[4] = "the children of hurin";
        array[5] = "the red b" +
                "+adge of courage";
        array[6] = "of mice and men";
        array[7] =  "utopia"; 
        array[8] =  "chariots of the gods";
        array[9] =  "a brief history of time";

        ArrayList<String> list = new ArrayList<String>(Arrays.asList(array));
        Collections.shuffle(list);
        String s = list.get(0);
        return s;
    }

    public StringBuilder dashReplace(String s) {
        //replace non-white space char with dashes and creates StringBuilder Object
        String tW = s.replaceAll("\\S", "-"); 
        System.out.print(tW + "\n");  
        StringBuilder AnswerKey = new StringBuilder(tW);
        return AnswerKey;
    }
    public static int findAndReplace(String s, JLabel answerKey, String sc,
            char ch) {
        //find position of user input and replace
        int pos = -1;
        FOUND = false;
        while(true){
        pos = s.indexOf(sc, pos+1);
        if(pos < 0){

            break;
        }else{
            FOUND = true;
            //setCharAt dosen't work for JLable
            answerKey.setCharAt(pos, ch);
        }

        }
        JLabel AnswerKey2 = new JLabel(answerKey.toString());
        return pos;
    }




    public HangmanPanel(final String s){
        this.setLayout(null);

        JLabel heading = new JLabel("Welcome to the Hangman App");
        JButton Button = new JButton("Ok");
        //get input

        JLabel tfLable = new JLabel("Please Enter a Letter:");


        final JLabel AnswerKey = new JLabel(dashReplace(answerKey()).toString());

        final JTextField text = new JTextField(10);


        heading.setSize(200, 50);
        tfLable.setSize(150, 50);
        text.setSize(50, 30);
        Button.setSize(60, 20);
        AnswerKey.setSize(200, 100);

        heading.setLocation(300, 10);
        tfLable.setLocation(50, 40);
        text.setLocation(50, 80);
        Button.setLocation(100, 85);
        AnswerKey.setLocation(100,85);

        this.add(heading);
        this.add(tfLable);
        this.add(text);
        this.add(Button);
        this.add(AnswerKey);


        Button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // can't access text
                String sc = text.getText();
                char ch = sc.charAt(0);
                findAndReplace(s, AnswerKey, sc, ch);
            }
        });

    }

}

Answer 1

为什么要尝试将setCharAt（...）与JLabel一起使用。标签用于显示静态文本。更改它的唯一方法是替换整个字符串。

我猜你可以这样做：

StringBuilder text = label.getText();
text.setCharAt(...);
label.setText( text.toString() );

另一种选择是使用看起来像JLabel的JTextField：

JTextField label = new JTextField(...);
label.setEditable(false);
label.setBorder(null);
label.setOpaque(false);

然后当您需要更改文本时：

label.select(...);
label.replaceSelection(...);

Answer 2

可用于为JLabel组件设置文本的唯一方法是setText。 Strings也是不可变的。因此，您可以使用StringBuilder：

StringBuilder builder = new StringBuilder(answerKey.getText());
builder.setCharAt(pos, ch);
answerKey.setText(builder.toString());