java - 数组到字符串以附加到 JFrame GUI 中的文本区域？

Question

我有一个Arraylist<ActivityPerformed> activityPerformed我想打印到 textArea作为 String printReport() 的一部分.

这就是我现在所拥有的(位于 Tracker.class 中)

public String getActivityPerformed() {
    String done = "";
    String error = "No tracked activities.\n";
    for(int i = 0; i < activityPerformed.size(); i++) {
        done += activityPerformed.get(i);
        done += "\n";
        return done;
    }
    return error;
}

public String printReport()
{   
    lifestyleReport  = "\n \nLifestyle Report \n";
    lifestyleReport += "Activities Performed \n" + getActivityPerformed();
    return lifestyleReport;
}

}

这就是我的 GUI (TrackerGUI.class):

public class Report implements ActionListener {
    public void actionPerformed (ActionEvent ae) {
        if(tracker.foodEaten.isEmpty() == true && tracker.activityPerformed.isEmpty() == true)
            textArea.append("Error: No food/activity tracked. \n");
        else textArea.append(tracker.printReport());
    }
}

我应该在代码中添加什么以使数组打印到textArea中适本地？我总是得到这样的东西:@365bc793

Answer 1

  for(int i = 0; i < activityPerformed.size(); i++) {
            done += activityPerformed.get(i);
                                        ^------------Object of ActivityPerformed
            done += "\n";
            return done;
        }

在上面的代码中，您从列表中获取元素索引 i，但类型为 ActivityPerformed，因此当您在 textarea 上打印时，对象会被打印。