Java 如何将多个edittext值传递到Arraylist中，然后将其发送到另一个活动？

我试图将5个edittext值传递到

Arraylist

中，然后将其发送到另一个活动。我使用intent将其发送到下一个活动，但它不断崩溃。我得到这个错误：

java.lang.NullPointerException:尝试从空数组读取

我认为我将值添加到arraylist中的方式是错误的，或者在intent中发送

arraylist

有问题

活动1：

EditText p1, p2, p3, p4, p5;
ArrayList<String> playerList = new ArrayList<>();
BootstrapButton btnStart;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnStart = (BootstrapButton) findViewById(R.id.start);
    p1 = (EditText) findViewById(R.id.player1);
    p2 = (EditText) findViewById(R.id.player2);
    p3 = (EditText) findViewById(R.id.player3);
    p4 = (EditText) findViewById(R.id.player4);
    p5 = (EditText) findViewById(R.id.player5);

    playerList.add(p1.getText().toString());
    playerList.add(p2.getText().toString());
    playerList.add(p3.getText().toString());
    playerList.add(p4.getText().toString());
    playerList.add(p5.getText().toString());

    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
            myIntent.putStringArrayListExtra("player_list", playerList);
            MainActivity.this.startActivity(myIntent);
        }

    });
  }

String[] array1={"asd","fgh","dcf","dg","ere","dsf"};
Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
myIntent.putExtra("player_list", array1);
MainActivity.this.startActivity(myIntent);

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnStart = (BootstrapButton) findViewById(R.id.start);
    p1 = (EditText) findViewById(R.id.player1);
    p2 = (EditText) findViewById(R.id.player2);
    p3 = (EditText) findViewById(R.id.player3);
    p4 = (EditText) findViewById(R.id.player4);
    p5 = (EditText) findViewById(R.id.player5);

    playerList.add(p1.getText().toString());
    playerList.add(p2.getText().toString());
    playerList.add(p3.getText().toString());
    playerList.add(p4.getText().toString());
    playerList.add(p5.getText().toString());

    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
            myIntent.putStringArrayListExtra("player_list", playerList);
            MainActivity.this.startActivity(myIntent);
        }

    });
  }

活动2：

TextView playerName;
ArrayList<String> playerList = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    playerName = (TextView) findViewById(R.id.playerName);

    Intent myIntent = getIntent();
    if(myIntent != null){
        playerList = myIntent.getStringArrayListExtra("player_list");
        playerName.setText(playerList.get(0));
    }
  }

    Intent myIntent = getIntent();
    if(myIntent != null){
        String[] players = myIntent.getStringArrayExtra("player_list");
        playerName.setText(players[2]);
    }else{
        System.out.println("Error!");
    }

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    playerName = (TextView) findViewById(R.id.playerName);

    Intent myIntent = getIntent();
    if(myIntent != null){
            ArrayList<String> players = myIntent.getStringArrayListExtra("player_list");
            playerName.setText(players.get(0));
        }else{
            System.out.println("Error!");
        }
      }

---

我想做的是有一个像这样的

[“p1”、“p2”、“p3”、“p4”、“p5”]

的

Arraylist

，然后在下一个活动中检索

Arraylist

并从该数组打印出一个随机名称。

使用

GetStringArrayListRA

而不是

getStringArrayExtra

if(myIntent != null){
        String[] players = myIntent.getStringArrayListExtra("player_list");
        playerName.setText(players[2]);
    }

---

使用

getStringArrayListExtra

not

getStringArrayExtra

if(myIntent != null){
        String[] players = myIntent.getStringArrayListExtra("player_list");
        playerName.setText(players[2]);
    }

---

在活动1中使用

intent.putStringArrayListExtra

发送字符串，在活动2中使用

getStringArrayListExtra（）

检索字符串arraylistra

以下是执行此操作的代码：

活动1：

EditText p1, p2, p3, p4, p5;
ArrayList<String> playerList = new ArrayList<>();
BootstrapButton btnStart;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnStart = (BootstrapButton) findViewById(R.id.start);
    p1 = (EditText) findViewById(R.id.player1);
    p2 = (EditText) findViewById(R.id.player2);
    p3 = (EditText) findViewById(R.id.player3);
    p4 = (EditText) findViewById(R.id.player4);
    p5 = (EditText) findViewById(R.id.player5);

    playerList.add(p1.getText().toString());
    playerList.add(p2.getText().toString());
    playerList.add(p3.getText().toString());
    playerList.add(p4.getText().toString());
    playerList.add(p5.getText().toString());

    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
            myIntent.putStringArrayListExtra("player_list", playerList);
            MainActivity.this.startActivity(myIntent);
        }

    });
  }

String[] array1={"asd","fgh","dcf","dg","ere","dsf"};
Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
myIntent.putExtra("player_list", array1);
MainActivity.this.startActivity(myIntent);

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnStart = (BootstrapButton) findViewById(R.id.start);
    p1 = (EditText) findViewById(R.id.player1);
    p2 = (EditText) findViewById(R.id.player2);
    p3 = (EditText) findViewById(R.id.player3);
    p4 = (EditText) findViewById(R.id.player4);
    p5 = (EditText) findViewById(R.id.player5);

    playerList.add(p1.getText().toString());
    playerList.add(p2.getText().toString());
    playerList.add(p3.getText().toString());
    playerList.add(p4.getText().toString());
    playerList.add(p5.getText().toString());

    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
            myIntent.putStringArrayListExtra("player_list", playerList);
            MainActivity.this.startActivity(myIntent);
        }

    });
  }

活动2：

TextView playerName;
ArrayList<String> playerList = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    playerName = (TextView) findViewById(R.id.playerName);

    Intent myIntent = getIntent();
    if(myIntent != null){
        playerList = myIntent.getStringArrayListExtra("player_list");
        playerName.setText(playerList.get(0));
    }
  }

    Intent myIntent = getIntent();
    if(myIntent != null){
        String[] players = myIntent.getStringArrayExtra("player_list");
        playerName.setText(players[2]);
    }else{
        System.out.println("Error!");
    }

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    playerName = (TextView) findViewById(R.id.playerName);

    Intent myIntent = getIntent();
    if(myIntent != null){
            ArrayList<String> players = myIntent.getStringArrayListExtra("player_list");
            playerName.setText(players.get(0));
        }else{
            System.out.println("Error!");
        }
      }

@覆盖
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_游戏）；
setRequestedOrientation（ActivityInfo.SCREEN\u ORIENTATION\u横向）；
playerName=（TextView）findViewById（R.id.playerName）；
Intent myIntent=getIntent（）；
if（myIntent！=null）{
ArrayList players=myIntent.getStringArrayListExtra（“玩家列表”）；
playerName.setText（players.get（0））；
}否则{
System.out.println（“错误！”）；
}
}

---

还要确保声明并初始化了playerList。您的代码没有显示它正在声明或初始化。

在活动1中使用

intent.putStringArrayListExtra

发送，在活动2中使用

getStringArrayListExtra（）

检索字符串arraylistra

以下是执行此操作的代码：

活动1：

EditText p1, p2, p3, p4, p5;
ArrayList<String> playerList = new ArrayList<>();
BootstrapButton btnStart;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnStart = (BootstrapButton) findViewById(R.id.start);
    p1 = (EditText) findViewById(R.id.player1);
    p2 = (EditText) findViewById(R.id.player2);
    p3 = (EditText) findViewById(R.id.player3);
    p4 = (EditText) findViewById(R.id.player4);
    p5 = (EditText) findViewById(R.id.player5);

    playerList.add(p1.getText().toString());
    playerList.add(p2.getText().toString());
    playerList.add(p3.getText().toString());
    playerList.add(p4.getText().toString());
    playerList.add(p5.getText().toString());

    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
            myIntent.putStringArrayListExtra("player_list", playerList);
            MainActivity.this.startActivity(myIntent);
        }

    });
  }

String[] array1={"asd","fgh","dcf","dg","ere","dsf"};
Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
myIntent.putExtra("player_list", array1);
MainActivity.this.startActivity(myIntent);

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnStart = (BootstrapButton) findViewById(R.id.start);
    p1 = (EditText) findViewById(R.id.player1);
    p2 = (EditText) findViewById(R.id.player2);
    p3 = (EditText) findViewById(R.id.player3);
    p4 = (EditText) findViewById(R.id.player4);
    p5 = (EditText) findViewById(R.id.player5);

    playerList.add(p1.getText().toString());
    playerList.add(p2.getText().toString());
    playerList.add(p3.getText().toString());
    playerList.add(p4.getText().toString());
    playerList.add(p5.getText().toString());

    btnStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent myIntent = new Intent(MainActivity.this, GameActivity.class);
            myIntent.putStringArrayListExtra("player_list", playerList);
            MainActivity.this.startActivity(myIntent);
        }

    });
  }

活动2：

TextView playerName;
ArrayList<String> playerList = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    playerName = (TextView) findViewById(R.id.playerName);

    Intent myIntent = getIntent();
    if(myIntent != null){
        playerList = myIntent.getStringArrayListExtra("player_list");
        playerName.setText(playerList.get(0));
    }
  }

    Intent myIntent = getIntent();
    if(myIntent != null){
        String[] players = myIntent.getStringArrayExtra("player_list");
        playerName.setText(players[2]);
    }else{
        System.out.println("Error!");
    }

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    playerName = (TextView) findViewById(R.id.playerName);

    Intent myIntent = getIntent();
    if(myIntent != null){
            ArrayList<String> players = myIntent.getStringArrayListExtra("player_list");
            playerName.setText(players.get(0));
        }else{
            System.out.println("Error!");
        }
      }

@覆盖
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_游戏）；
setRequestedOrientation（ActivityInfo.SCREEN\u ORIENTATION\u横向）；
playerName=（TextView）findViewById（R.id.playerName）；
Intent myIntent=getIntent（）；
if（myIntent！=null）{
ArrayList players=myIntent.getStringArrayListExtra（“玩家列表”）；
playerName.setText（players.get（0））；
}否则{
System.out.println（“错误！”）；
}
}

---

还要确保声明并初始化了playerList。您的代码没有显示它正在声明或初始化。

编辑文本中是否有任何内容？一旦活动开始，您将立即从编辑文本中获取值。如果它们中没有任何内容，那么您实际上是在向数组中添加空字符串。是否声明了

playerList

？此外，在测试它们时，您使用的是

array

，在实际实现中，您使用的是

ArrayList

是的，使用ArrayListyou也在使用

getStringArrayExtra

尝试使用

GetStringArrayListRa

编辑文本中是否有任何内容？一旦活动开始，您将立即从编辑文本中获取值。如果它们中没有任何内容，那么您实际上是在向数组中添加空字符串。是否声明了

playerList

？此外，在测试它们时，您使用的是

array

，在实际实现中，您使用的是

ArrayList

是的，使用ArrayListyou也在使用

getStringArrayExtra

尝试使用

GetStringArrayListRa