Java 如何在if条件结束时返回数组列表的对象？

我有一个数组列表，它需要在最后返回allteams对象，但我不能这样做，当传递null时，它会出现null指针异常，请帮助我解决这个问题。以下是代码示例：

private ArrayList<Team> getData() {
    Intent localIntent = getIntent();
    localIntent.getIntExtra("det", 0);
    if (localIntent.hasExtra("beg")) {


        Team t1 = new Team("Day 1: Chest, Back, Shoulders, Legs, Biceps, Triceps");
        t1.players.add("Chest – Barbell Bench Press – 4 sets of 8 reps");
        t1.players.add("Back – Lat-pulldowns – 4 sets of 10 reps");
        t1.players.add("Shoulders – Seated Dumbbell Press – 4 sets of 10 reps");
        t1.players.add("Legs – Leg Extensions – 4 sets of 10 reps");
        t1.players.add("Biceps – Barbell Bbicep Curls – 3 sets of 10 reps");
        t1.players.add("Triceps – Triceps Rope Pushdowns – 3 sets of 15 reps");

        Team t2 = new Team("Day 2: Legs, Triceps, Biceps, Chest, Back, Shoulder");
        t2.players.add("Legs – Leg Press Machine – 4 sets of 8 reps");
        t2.players.add("Triceps – Overhead Bar Extensions – 3 sets of 20 reps");
        t2.players.add("Biceps – EZ Bar Curls – 4 sets of 10 reps");
        t2.players.add("Chest – Machine Chest Press – 4 sets of 10 reps");
        t2.players.add("Back – T-Bar Row – 4 sets of 10 reps");
        t2.players.add("Shoulders – Lateral Raises – 3 sets of 20 reps");

        Team t3 = new Team("Day 3: Shoulders, Back, Chest, Legs, Triceps, Biceps");
        t3.players.add("Shoulders – Upright Rows – 3 sets of 15 reps");
        t3.players.add("Back – Close-Grip Pulldowns – 4 sets of 12 reps");
        t3.players.add("Chest – Fly – 4 sets of 10 reps");
        t3.players.add("Legs – Lunges – 3 sets of 10 reps per leg");
        t3.players.add("Triceps – Skullcrushers – 3 sets of 15 reps");
        t3.players.add("Biceps – Hammer Curls – 3 sets of 12 reps");

        ArrayList<Team> allTeams = new ArrayList<Team>();
        allTeams.add(t1);
        allTeams.add(t2);
        allTeams.add(t3);

        return allTeams;


    } else if (localIntent.hasExtra("inter")) {

        Team t1 = new Team("Day 1: Chest, Shoulders and Triceps");
        t1.players.add("Bench Press – 3 sets of 10, 10, 8 (adding weight) reps");
        t1.players.add("Incline Dumbbell Bench Press – 3 sets of 10 reps");
        t1.players.add("Chest Dip – 3 sets of MAX reps");
        t1.players.add("Skullcrushers – 3 sets of 8-10 Reps");
        t1.players.add("One Arm Dumbbell Extension – 3 sets of 10 reps");
        t1.players.add("Tricep Extension – 3 sets of 10 reps");
        t1.players.add("Barbell Front Raise – 4 sets of 12 reps");
        t1.players.add("Dumbbell Lateral Raise – 4 sets of 15, 12, 8, 8 (adding weight) reps");

        Team t2 = new Team("Day 2: Back and Biceps");
        t2.players.add("Wide Grip Pull Up 3 sets of MAX reps");
        t2.players.add("Lat Pull Down – 3 sets of 10 reps");
        t2.players.add("Straight Arm Lat Pull Down – 3 sets of 10 reps");
        t2.players.add("Standing Barbell Curl – 3 sets of 8-10 reps");
        t2.players.add("Preacher Curl – 3 sets of 10 reps");
        t2.players.add("Incline Dumbbell Curl – 3 sets of 10 reps");


        Team t3 = new Team("Day 3: Legs");
        t3.players.add("Squat – 4 sets of 10,10,8,8 reps");
        t3.players.add("Dumbbell Lunge – 3 sets of 8 on each leg");
        t3.players.add("Leg Press – 3 sets of 12 reps");
        t3.players.add("Leg Curl – 3 sets of 15 reps");
        t3.players.add("Leg Extension – 3 sets of 15 reps");
        t3.players.add("Standing Calf Raise – 5 sets of 10,8,8,8,6 (heavy)reps");
        t3.players.add("Seated Calf Raise – 5 sets of 15 (light) reps");

        Team t4 = new Team("Day 4:  Shoulders, chest, and Triceps");
        t4.players.add("Barbell Bench Press – 3 sets of 10, 10, 8 reps");
        t4.players.add("Dumbbell Flys – 3 sets of 10 reps");
        t4.players.add("Cable Crossovers – 3 sets of 10 reps");
        t4.players.add("Close Grip Bench Press – 4 sets of 10, 10, 8, 6 reps");
        t4.players.add("Lying Dumbbell Extension – 3 sets of 10 reps");
        t4.players.add("Tricep Kickback – 3 sets of 10 reps");
        t4.players.add("Seated Dumbbell Press – 4 sets of 10, 10, 8, 8 reps");
        t4.players.add("One Arm Cable Lateral Raise – 3 sets of 12 reps");

        Team t5 = new Team("Day 5: Back and Biceps");
        t5.players.add("Seated Row – 4 sets of 10 reps");
        t5.players.add("Bent Over Barbell Row – 3 sets of 10 reps");
        t5.players.add("Bent Over Row – 3 sets of 12 reps");
        t5.players.add("Smith Machine Upright Row – 3 sets of 8-10 reps");
        t5.players.add("Cable Curl – 4 sets of 8-10 reps");
        t5.players.add("Concentration Curl – 3 sets of 10 reps");
        t5.players.add("Reverse Barbell Curl – 3 sets of 10 reps");

        ArrayList<Team> allTeams = new ArrayList<Team>();
        allTeams.add(t1);
        allTeams.add(t2);
        allTeams.add(t3);
        allTeams.add(t4);
        allTeams.add(t5);

        return allTeams;
    }
    return null;
}

private ArrayList getData（）{
Intent localIntent=getIntent（）；
localIntent.getIntExtra（“det”，0）；
if（localIntent.hasExtra（“beg”））{
团队t1=新团队（“第1天：胸部、背部、肩部、腿部、二头肌、三头肌”）；
t1.球员。增加（“胸部-杠铃卧推-4组，共8次”）；
t1.玩家。添加（“后退–横向下拉–4组10次重复”）；
t1.球员。增加（“肩部-坐姿哑铃按压-4组10次”）；
t1.玩家。添加（“腿部-腿部伸展-4组10次重复”）；
t1.球员。添加（“二头肌-杠铃Bbicep卷发-3套10次”）；
t1.球员。添加（“三头肌-三头肌绳索下推-3组15次”）；
团队t2=新团队（“第2天：腿部、三头肌、二头肌、胸部、背部、肩部”）；
t2.玩家。添加（“腿部-腿部按压机-4套，共8次”）；
t2.球员。添加（“三头肌-头顶杆延长-3组，共20次”）；
t2.运动员。添加（“二头肌–EZ杆卷发–4组，共10次”）；
t2.玩家。添加（“胸部-机器胸部按压-4套10次”）；
t2.球员。添加（“背部-T形杆排-4组，共10次”）；
t2.运动员。增加（“肩部-侧向抬高-3组，共20次”）；
t3组=新团队（“第3天：肩部、背部、胸部、腿部、三头肌、二头肌”）；
t3.球员。添加（“肩部-直排-3组，共15次”）；
t3.玩家。添加（“背部-紧握下拉-4组，共12次”）；
t3.玩家。添加（“胸部-飞行-4套10次”）；
t3.运动员。添加（“腿-弓箭步-3组，每组10次”）；
t3.玩家。添加（“三头肌-碎头骨-3组，共15次”）；
t3.球员。添加（“二头肌-链球-3组，共12次”）；
ArrayList allTeams=新的ArrayList（）；
所有团队。添加（t1）；
所有团队。添加（t2）；
所有团队。添加（t3）；
返回所有团队；
}else if（localIntent.hasExtra（“inter”））{
t1组=新团队（“第1天：胸部、肩部和三头肌”）；
t1.球员。增加（“卧推-3套10、10、8（增加重量）重复”）；
t1.球员。增加（“倾斜哑铃卧推-3套10次”）；
t1.玩家。添加（“胸部下倾–3组最大重复次数”）；
t1.玩家。添加（“碎骨机–3套，共8-10次”）；
t1.玩家。添加（“单臂哑铃伸展-3套10次”）；
t1.运动员。增加（“三头肌伸展-3组10次”）；
t1.球员。添加（“杠铃前举-4组，共12次”）；
t1.球员。增加（“哑铃横向提升–4组15、12、8、8（增加重量）重复”）；
团队t2=新团队（“第2天：背部和二头肌”）；
t2.球员。增加（“宽握拉起3组最大重复次数”）；
t2.玩家。添加（“横向下拉–3组，共10次”）；
t2.玩家。添加（“直臂横向下拉–3组，共10次”）；
t2.运动员。添加（“站立杠铃卷曲-3组，共8-10次”）；
t2.玩家。添加（“牧师卷发–3套10次”）；
t2.运动员。增加（“倾斜哑铃卷曲-3组，共10次”）；
t3团队=新团队（“第3天：腿部”）；
t3.玩家。添加（“下蹲–4组10,10,8,8次重复”）；
t3.运动员。增加（“哑铃弓箭步-每条腿3组，每组8个”）；
t3.球员。添加（“腿部按压–3组，共12次”）；
t3.球员。添加（“曲腿–3组，共15次”）；
t3.球员。添加（“腿部伸展-3组，共15次”）；
t3.玩家。添加（“站立小腿抬高-5组10,8,8,6（重）次”）；
t3.玩家。添加（“坐式小腿抬高–5组15次（轻）重复”）；
t4组=新团队（“第4天：肩部、胸部和三头肌”）；
t4.球员。添加（“杠铃板凳压-3套10、10、8次”）；
t4.玩家。添加（“哑铃飞-3套10次”）；
t4.玩家。添加（“电缆交叉-3套10次重复”）；
t4.球员。增加（“紧握式板凳压力机–4套10、10、8、6次重复”）；
t4.玩家。添加（“卧式哑铃伸展-3套10次”）；
t4.球员。添加（“三头肌回扣–3组，共10次”）；
t4.玩家。添加（“坐式哑铃按压-4套，共10、10、8、8次”）；
t4.球员。添加（“单臂缆绳横向提升–3组，共12次”）；
团队t5=新团队（“第5天：背部和二头肌”）；
t5.玩家。添加（“坐着的一排–4组，共10次”）；
t5.球员。添加（“俯身杠铃排–3组，共10次”）；
t5.玩家。添加（“弯腰行–3组，共12次”）；
t5.玩家。添加（“史密斯机器直立排–3组，共8-10次”）；
t5.玩家。添加（“电缆卷曲–4套，共8-10次”）；
t5.玩家。添加（“集中卷曲-3组10次”）；
t5.运动员。添加（“反向杠铃卷曲-3套10次”）；
ArrayList allTeams=新的ArrayList（）；
所有团队。添加（t1）；
所有团队。添加（t2）；
所有团队。添加（t3）；
所有团队。添加（t4）；
所有团队。添加（t5）；
返回所有团队；
}
返回null；
}

---

请帮助我解决这个问题我能做些什么来解决这个问题，在结束时它应该返回AllTeam而不是null。

根据这些代码，如果不匹配任何东西，它的返回null对于这些情况添加last else并设置它的默认值。无论它的null是否匹配，它都执行else语句

if()
{
}
else if()
 {
 }
else  {
    Team t1 = new Team("Day 1: Chest, Shoulders and Triceps");
    t1.players.add("Bench Press – 3 sets of 10, 10, 8 (adding weight) reps");
    t1.players.add("Incline Dumbbell Bench Press – 3 sets of 10 reps");
    t1.players.add("Chest Dip – 3 sets of MAX reps");
    t1.players.add("Skullcrushers – 3 sets of 8-10 Reps");
    t1.players.add("One Arm Dumbbell Extension – 3 sets of 10 reps");
    t1.players.add("Tricep Extension – 3 sets of 10 reps");
    t1.players.add("Barbell Front Raise – 4 sets of 12 reps");
    t1.players.add("Dumbbell Lateral Raise – 4 sets of 15, 12, 8, 8 (adding weight) reps");
    ArrayList<Team> allTeams = new ArrayList<Team>();
    allTeams.add(t1);       
    return allTeams;
}

if（）
{
}
else if（）
{
}
否则{
t1组=新团队（“第1天：胸部、肩部和三头肌”）；
t1.球员。增加（“卧推-3套10、10、8（增加重量）重复”）；
t1.球员。增加（“倾斜哑铃卧推-3套10次”）；
t1.玩家。添加（“胸部下倾–3组最大重复次数”）；
t1.玩家。添加（“碎骨机–3套，共8-10次”）；
T
private ArrayList<Team> getData() {
   Intent localIntent = getIntent();
   localIntent.getIntExtra("det", 0);
   ArrayList<Team> allTeams = new ArrayList<Team>();

   if (localIntent.hasExtra("beg")) {


    Team t1 = new Team("Day 1: Chest, Back, Shoulders, Legs, Biceps, Triceps");
    t1.players.add("Chest – Barbell Bench Press – 4 sets of 8 reps");
    t1.players.add("Back – Lat-pulldowns – 4 sets of 10 reps");
    t1.players.add("Shoulders – Seated Dumbbell Press – 4 sets of 10 reps");
    t1.players.add("Legs – Leg Extensions – 4 sets of 10 reps");
    t1.players.add("Biceps – Barbell Bbicep Curls – 3 sets of 10 reps");
    t1.players.add("Triceps – Triceps Rope Pushdowns – 3 sets of 15 reps");

    Team t2 = new Team("Day 2: Legs, Triceps, Biceps, Chest, Back, Shoulder");
    t2.players.add("Legs – Leg Press Machine – 4 sets of 8 reps");
    t2.players.add("Triceps – Overhead Bar Extensions – 3 sets of 20 reps");
    t2.players.add("Biceps – EZ Bar Curls – 4 sets of 10 reps");
    t2.players.add("Chest – Machine Chest Press – 4 sets of 10 reps");
    t2.players.add("Back – T-Bar Row – 4 sets of 10 reps");
    t2.players.add("Shoulders – Lateral Raises – 3 sets of 20 reps");

    Team t3 = new Team("Day 3: Shoulders, Back, Chest, Legs, Triceps, Biceps");
    t3.players.add("Shoulders – Upright Rows – 3 sets of 15 reps");
    t3.players.add("Back – Close-Grip Pulldowns – 4 sets of 12 reps");
    t3.players.add("Chest – Fly – 4 sets of 10 reps");
    t3.players.add("Legs – Lunges – 3 sets of 10 reps per leg");
    t3.players.add("Triceps – Skullcrushers – 3 sets of 15 reps");
    t3.players.add("Biceps – Hammer Curls – 3 sets of 12 reps");

    allTeams.add(t1);
    allTeams.add(t2);
    allTeams.add(t3);

    return allTeams;


} else if (localIntent.hasExtra("inter")) {

    Team t1 = new Team("Day 1: Chest, Shoulders and Triceps");
    t1.players.add("Bench Press – 3 sets of 10, 10, 8 (adding weight) reps");
    t1.players.add("Incline Dumbbell Bench Press – 3 sets of 10 reps");
    t1.players.add("Chest Dip – 3 sets of MAX reps");
    t1.players.add("Skullcrushers – 3 sets of 8-10 Reps");
    t1.players.add("One Arm Dumbbell Extension – 3 sets of 10 reps");
    t1.players.add("Tricep Extension – 3 sets of 10 reps");
    t1.players.add("Barbell Front Raise – 4 sets of 12 reps");
    t1.players.add("Dumbbell Lateral Raise – 4 sets of 15, 12, 8, 8 (adding weight) reps");

    Team t2 = new Team("Day 2: Back and Biceps");
    t2.players.add("Wide Grip Pull Up 3 sets of MAX reps");
    t2.players.add("Lat Pull Down – 3 sets of 10 reps");
    t2.players.add("Straight Arm Lat Pull Down – 3 sets of 10 reps");
    t2.players.add("Standing Barbell Curl – 3 sets of 8-10 reps");
    t2.players.add("Preacher Curl – 3 sets of 10 reps");
    t2.players.add("Incline Dumbbell Curl – 3 sets of 10 reps");


    Team t3 = new Team("Day 3: Legs");
    t3.players.add("Squat – 4 sets of 10,10,8,8 reps");
    t3.players.add("Dumbbell Lunge – 3 sets of 8 on each leg");
    t3.players.add("Leg Press – 3 sets of 12 reps");
    t3.players.add("Leg Curl – 3 sets of 15 reps");
    t3.players.add("Leg Extension – 3 sets of 15 reps");
    t3.players.add("Standing Calf Raise – 5 sets of 10,8,8,8,6 (heavy)reps");
    t3.players.add("Seated Calf Raise – 5 sets of 15 (light) reps");

    Team t4 = new Team("Day 4:  Shoulders, chest, and Triceps");
    t4.players.add("Barbell Bench Press – 3 sets of 10, 10, 8 reps");
    t4.players.add("Dumbbell Flys – 3 sets of 10 reps");
    t4.players.add("Cable Crossovers – 3 sets of 10 reps");
    t4.players.add("Close Grip Bench Press – 4 sets of 10, 10, 8, 6 reps");
    t4.players.add("Lying Dumbbell Extension – 3 sets of 10 reps");
    t4.players.add("Tricep Kickback – 3 sets of 10 reps");
    t4.players.add("Seated Dumbbell Press – 4 sets of 10, 10, 8, 8 reps");
    t4.players.add("One Arm Cable Lateral Raise – 3 sets of 12 reps");

    Team t5 = new Team("Day 5: Back and Biceps");
    t5.players.add("Seated Row – 4 sets of 10 reps");
    t5.players.add("Bent Over Barbell Row – 3 sets of 10 reps");
    t5.players.add("Bent Over Row – 3 sets of 12 reps");
    t5.players.add("Smith Machine Upright Row – 3 sets of 8-10 reps");
    t5.players.add("Cable Curl – 4 sets of 8-10 reps");
    t5.players.add("Concentration Curl – 3 sets of 10 reps");
    t5.players.add("Reverse Barbell Curl – 3 sets of 10 reps");

    allTeams.add(t1);
    allTeams.add(t2);
    allTeams.add(t3);
    allTeams.add(t4);
    allTeams.add(t5);

    return allTeams;
    }
  return allTeams;
}

private ArrayList<Team> getData() {
Intent localIntent = getIntent();
localIntent.getIntExtra("det", 0);
ArrayList<Team> allTeams = new ArrayList<Team>();
if (localIntent.hasExtra("beg")) {


    Team t1 = new Team("Day 1: Chest, Back, Shoulders, Legs, Biceps, Triceps");
    t1.players.add("Chest – Barbell Bench Press – 4 sets of 8 reps");
    t1.players.add("Back – Lat-pulldowns – 4 sets of 10 reps");
    t1.players.add("Shoulders – Seated Dumbbell Press – 4 sets of 10 reps");
    t1.players.add("Legs – Leg Extensions – 4 sets of 10 reps");
    t1.players.add("Biceps – Barbell Bbicep Curls – 3 sets of 10 reps");
    t1.players.add("Triceps – Triceps Rope Pushdowns – 3 sets of 15 reps");

    Team t2 = new Team("Day 2: Legs, Triceps, Biceps, Chest, Back, Shoulder");
    t2.players.add("Legs – Leg Press Machine – 4 sets of 8 reps");
    t2.players.add("Triceps – Overhead Bar Extensions – 3 sets of 20 reps");
    t2.players.add("Biceps – EZ Bar Curls – 4 sets of 10 reps");
    t2.players.add("Chest – Machine Chest Press – 4 sets of 10 reps");
    t2.players.add("Back – T-Bar Row – 4 sets of 10 reps");
    t2.players.add("Shoulders – Lateral Raises – 3 sets of 20 reps");

    Team t3 = new Team("Day 3: Shoulders, Back, Chest, Legs, Triceps, Biceps");
    t3.players.add("Shoulders – Upright Rows – 3 sets of 15 reps");
    t3.players.add("Back – Close-Grip Pulldowns – 4 sets of 12 reps");
    t3.players.add("Chest – Fly – 4 sets of 10 reps");
    t3.players.add("Legs – Lunges – 3 sets of 10 reps per leg");
    t3.players.add("Triceps – Skullcrushers – 3 sets of 15 reps");
    t3.players.add("Biceps – Hammer Curls – 3 sets of 12 reps");

    allTeams.add(t1);
    allTeams.add(t2);
    allTeams.add(t3);


} else if (localIntent.hasExtra("inter")) {

    Team t1 = new Team("Day 1: Chest, Shoulders and Triceps");
    t1.players.add("Bench Press – 3 sets of 10, 10, 8 (adding weight) reps");
    t1.players.add("Incline Dumbbell Bench Press – 3 sets of 10 reps");
    t1.players.add("Chest Dip – 3 sets of MAX reps");
    t1.players.add("Skullcrushers – 3 sets of 8-10 Reps");
    t1.players.add("One Arm Dumbbell Extension – 3 sets of 10 reps");
    t1.players.add("Tricep Extension – 3 sets of 10 reps");
    t1.players.add("Barbell Front Raise – 4 sets of 12 reps");
    t1.players.add("Dumbbell Lateral Raise – 4 sets of 15, 12, 8, 8 (adding weight) reps");

    Team t2 = new Team("Day 2: Back and Biceps");
    t2.players.add("Wide Grip Pull Up 3 sets of MAX reps");
    t2.players.add("Lat Pull Down – 3 sets of 10 reps");
    t2.players.add("Straight Arm Lat Pull Down – 3 sets of 10 reps");
    t2.players.add("Standing Barbell Curl – 3 sets of 8-10 reps");
    t2.players.add("Preacher Curl – 3 sets of 10 reps");
    t2.players.add("Incline Dumbbell Curl – 3 sets of 10 reps");


    Team t3 = new Team("Day 3: Legs");
    t3.players.add("Squat – 4 sets of 10,10,8,8 reps");
    t3.players.add("Dumbbell Lunge – 3 sets of 8 on each leg");
    t3.players.add("Leg Press – 3 sets of 12 reps");
    t3.players.add("Leg Curl – 3 sets of 15 reps");
    t3.players.add("Leg Extension – 3 sets of 15 reps");
    t3.players.add("Standing Calf Raise – 5 sets of 10,8,8,8,6 (heavy)reps");
    t3.players.add("Seated Calf Raise – 5 sets of 15 (light) reps");

    Team t4 = new Team("Day 4:  Shoulders, chest, and Triceps");
    t4.players.add("Barbell Bench Press – 3 sets of 10, 10, 8 reps");
    t4.players.add("Dumbbell Flys – 3 sets of 10 reps");
    t4.players.add("Cable Crossovers – 3 sets of 10 reps");
    t4.players.add("Close Grip Bench Press – 4 sets of 10, 10, 8, 6 reps");
    t4.players.add("Lying Dumbbell Extension – 3 sets of 10 reps");
    t4.players.add("Tricep Kickback – 3 sets of 10 reps");
    t4.players.add("Seated Dumbbell Press – 4 sets of 10, 10, 8, 8 reps");
    t4.players.add("One Arm Cable Lateral Raise – 3 sets of 12 reps");

    Team t5 = new Team("Day 5: Back and Biceps");
    t5.players.add("Seated Row – 4 sets of 10 reps");
    t5.players.add("Bent Over Barbell Row – 3 sets of 10 reps");
    t5.players.add("Bent Over Row – 3 sets of 12 reps");
    t5.players.add("Smith Machine Upright Row – 3 sets of 8-10 reps");
    t5.players.add("Cable Curl – 4 sets of 8-10 reps");
    t5.players.add("Concentration Curl – 3 sets of 10 reps");
    t5.players.add("Reverse Barbell Curl – 3 sets of 10 reps");

    allTeams.add(t1);
    allTeams.add(t2);
    allTeams.add(t3);
    allTeams.add(t4);
    allTeams.add(t5);

}
return allTeams;
}

ArrayList teamList = getData()
if(teamList.isNotEmpty()){
*do your stuff with teamList here*
}