带有条件的java字符串toString

Question

我必须编写一个 PhonePlan 对象，该对象将代表客户为其手机制定的计划类型。所以对象必须跟踪 minutesAllowed (int)、minutes used (int)、dataAllowed (int)、data used (int) 和 planType (boolean)：

public class PhonePlan {
     int minutesAllowed;
     int minutesUsed;
     int dataAllowed;
     int dataUsed;
     boolean planType;
}

我需要编写一个构造函数，其中包含 minutesAllowed、dataAllowed 和 planType 作为我所做的参数：

public PhonePlan (int ma, int da, boolean pt){
    this.minutesAllowed = ma;
    this.planType = pt;
    this.dataAllowed = da;
}

最后我必须编写一个字符串方法，根据计划的类型显示计划。

我还必须使用以下测试程序测试我的代码；

public class PlanTestProgram {
    public static void main(String args[]) {

        System.out.println(new PhonePlan(200, 2500000, false));
        System.out.println(new PhonePlan(250, 500000, true));
        System.out.println(new PhonePlan(300, 5000000, false));
        System.out.println(new PhonePlan(60, 1000000, false));
        System.out.println(new PhonePlan(30, 0, true));
    }

第一个元素是 minutesAllowed，第二个是 dataAllowed 的数量，第三个是说明 planType 是 true 还是 false。

我尝试了很多不同的方法，但我无法构造一个 toString() 方法来考虑我的 planType 是真还是假...

我的尝试：

public String toString(){ 
    return ( "Regular(" + minutesAllowed + " minute," + dataAllowed 
              + "GB data) Monthly Plan with " 
              + getMinutesRemaining() + " minutes remaining and " 
              + getDataRemaining() + "KB remaining"); 
}

Answer 1

您可以使用 if/else 简写方式轻松地将建议（尝试）toString 方法中的 return 更新为以下内容：

return ("Regular(" + minutesAllowed + " minute," + dataAllowed 
          + "GB data) " + ((PlanType)? "Monthly": "Annual") + " Plan with " 
          + getMinutesRemaining() + " minutes remaining and " 
          + getDataRemaining() + "KB remaining");

Answer 2

Metod toString() 绝不能用于展示对象属性的价值。对于覆盖，您可以使用公共库

public String toString() {
 return new ToStringBuilder(this).
   append("minutesAllowed", minutesAllowed).
   append("minutesUsed", minutesUsed).
   append("dataAllowed", dataAllowed).
   append("dataUsed", dataUsed).
   append("planType", planType).
   toString();
}

Answer 3

你可以按照下面的代码实现 toString 方法

public class PhonePlan {
int minutesAllowed;
int minutesUsed;
int dataAllowed;
int dataUsed;
boolean planType;
public PhonePlan (int ma, int da, boolean pt){
    this.minutesAllowed = ma;
    this.planType = pt;
    this.dataAllowed = da;
}



@Override
public String toString() {
    return planType ? getPlanTypeBasedString("Weekly Plan") : getPlanTypeBasedString("Monthly Plan");
}
public String getPlanTypeBasedString(String planType){
    return ( "Regular(" + minutesAllowed + " minute," + dataAllowed
            + "GB data) "+planType+" with "
            + getMinutesRemaining() + " minutes remaining and "
            + getDataRemaining() + "KB remaining");
}