Java Netbeans 8.0 Jframe GUI程序 - arraylist中的每个索引值都没有显示在jtextArea中的各行上
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我正在研究我课程中的另一个程序，我们应该创建一个程序，用一个整数的arraylist（即一个类的标记）执行多个函数。我的问题是，当我尝试按升序输出“marks”arraylist的值时，每个值都在它自己的行上，它只显示最近输入的值。
例如，如果我输入25然后输入54并单击“排序”按钮，则Jtextarea中仅显示54。我的代码如下所示，请注意问题在sortButtonActionPerformed方法中。
import java.util.*;
public class MarksGUI extends javax.swing.JFrame {
ArrayList <Integer> marks = new ArrayList();
ArrayList <Integer> marksSorted = new ArrayList();
int numlvlR=0;
int numlvl1=0;
int numlvl2=0;
int numlvl3=0;
int numlvl4=0;
public MarksGUI() {
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
titleLabel = new javax.swing.JLabel();
markLabel = new javax.swing.JLabel();
markInput = new javax.swing.JTextField();
addButton = new javax.swing.JButton();
jScrollPane1 = new javax.swing.JScrollPane();
analyzeField = new javax.swing.JTextArea();
jScrollPane2 = new javax.swing.JScrollPane();
classmarksField = new javax.swing.JTextArea();
sortButton = new javax.swing.JButton();
analyzeButton = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
titleLabel.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
titleLabel.setForeground(new java.awt.Color(0, 0, 204));
titleLabel.setText("Marks Program");
markLabel.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
markLabel.setText("Student Mark:");
addButton.setText("Add");
addButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
addButtonActionPerformed(evt);
}
});
analyzeField.setEditable(false);
analyzeField.setColumns(20);
analyzeField.setRows(5);
jScrollPane1.setViewportView(analyzeField);
classmarksField.setEditable(false);
classmarksField.setColumns(20);
classmarksField.setRows(5);
jScrollPane2.setViewportView(classmarksField);
sortButton.setText("Sort");
sortButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
sortButtonActionPerformed(evt);
}
});
analyzeButton.setText("Analyze");
analyzeButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
analyzeButtonActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(0, 32, Short.MAX_VALUE)
.addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(42, 42, 42))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(107, 107, 107)
.addComponent(titleLabel))
.addGroup(layout.createSequentialGroup()
.addGap(75, 75, 75)
.addComponent(markLabel)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(markInput, javax.swing.GroupLayout.PREFERRED_SIZE, 58, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(addButton)))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGroup(layout.createSequentialGroup()
.addGap(86, 86, 86)
.addComponent(sortButton)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(analyzeButton)
.addGap(90, 90, 90))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(titleLabel)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(markInput, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(markLabel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(addButton))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jScrollPane2, javax.swing.GroupLayout.DEFAULT_SIZE, 245, Short.MAX_VALUE)
.addComponent(jScrollPane1))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sortButton)
.addComponent(analyzeButton))
.addContainerGap(19, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
//add method is working/////////////
private void addButtonActionPerformed(java.awt.event.ActionEvent evt) {
int newMarks;
newMarks = Integer.parseInt(markInput.getText());
marks.add(newMarks);
System.out.println(marks);//testing purposes
}
//problem is in sort method//////////////
private void sortButtonActionPerformed(java.awt.event.ActionEvent evt) {
int biggestMark = largestMark();//YOU WERE HERE///////////////////////////////////////////////////////////////////////////////////////////
for(int k = 0;k<marks.size();k++)
{
marksSorted.add((marks.get(k)));
System.out.println(marksSorted);//testing purposes
}
for(int x = 0;x<marks.size();x++)
{
Collections.sort(marksSorted);
classmarksField.setText(marksSorted.get(x)+"\n");
System.out.println(marksSorted);//testing purposes
}
}**
//working//////////////////////
private void analyzeButtonActionPerformed(java.awt.event.ActionEvent evt) {
int maxMark, minMark, mark;
analyzeField.setText("Class Average:"+classAverage()+"\n"+"Maximum Mark:"+largestMark()+"\n"+"Mininmum Mark:"+smallestMark()+"\n"+"Range of Marks:"+rangeofMarks()+"\n"+"Num at level 4:"+numlvl4+"\n"+"Num at level 3"+numlvl3+"\n"+"Num at level 2:"+numlvl2+"\n"+"Num at level 1:"+numlvl1+"\n"+"Num at level R:"+numlvlR);
}
public int classAverage(){
int marksTotal, marksAverage;
marksTotal = 0;
for(int i = 0; i<marks.size();i++){
marksTotal = marksTotal+marks.get(i);
}
marksAverage = marksTotal/marks.size();
return(marksAverage);
}
public int smallestMark(){
int smallestmarkValue;
smallestmarkValue = 100;
for(int y = 0; y<marks.size();y++){
if(marks.get(y)<=smallestmarkValue)
{
smallestmarkValue = marks.get(y);
}
else
{
}
}
return(smallestmarkValue);
}
public int largestMark(){
int largestmarkValue;
largestmarkValue = 0;
for(int z = 0; z<marks.size();z++){
if(marks.get(z)>=largestmarkValue)
{
largestmarkValue = marks.get(z);
}
else
{
}
}
return(largestmarkValue);
}
public int rangeofMarks(){
int range;
range = largestMark()-smallestMark();
return(range);
}
public int numwitheachlevel(){
int mark;
mark = 0;
for(int j = 0; j<marks.size();j++){
mark = marks.get(j);
if(mark<50)
{
numlvlR++;
}
else if((mark >= 50) && (mark < 60))
{
numlvl1++;
}
else if((mark >= 60) && (mark < 70))
{
numlvl2++;
}
else if((mark >= 70) && (mark < 80))
{
numlvl3++;
}
else if(mark >= 80)
{
numlvl4++;
}
//numeachlvl.addAll(numlvlR,numlvl1,numlvl2,numlvl3,numlvl4);
//return(numeachlvl);//you were here///////////////////////////////////////////////////////////////////////////////
}
//System.out.println("Range:"+rangeofMarks());
System.out.println("Largest mark"+largestMark());
System.out.println("Smallest mark:"+smallestMark());
System.out.println("Number at level R:"+numlvlR);
System.out.println("Number at level 1:"+numlvl1);
System.out.println("Number at level 2:"+numlvl2);
System.out.println("Number at level 3:"+numlvl3);
System.out.println("Number at level 4:"+numlvl4);
/**
* @param args the command line arguments
*/
public static void main(String args[]){
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(MarksGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(MarksGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(MarksGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(MarksGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MarksGUI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton addButton;
private javax.swing.JButton analyzeButton;
private javax.swing.JTextArea analyzeField;
private javax.swing.JTextArea classmarksField;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JTextField markInput;
private javax.swing.JLabel markLabel;
private javax.swing.JButton sortButton;
private javax.swing.JLabel titleLabel;
// End of variables declaration
}
答案
。例如，如果我输入25然后输入54并单击“排序”按钮，则Jtextarea中仅显示54
for(int x = 0;x<marks.size();x++)
{
Collections.sort(marksSorted);
classmarksField.setText(marksSorted.get(x)+"\n");
System.out.println(marksSorted);//testing purposes
}
如果从marks.size列表中获取数据，为什么使用markssorted来控制循环？排序不会创建数据的副本。
为什么每次循环都会对List进行排序？你期望改变什么？
你为什么要使用setText（...）？这将替换文本区域中的所有文本，因此您只能获取列表中的最后一个值。
使用JTextArea的append(...)方法。
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