ArrayList限制以容纳10个值

在您的处理程序方法中：

if(playerList.size() < 10) {   // playerList.add} else {   // do nothing}

编辑 ：您的错误在这里：

if(playerList.size() < 10) {    Button confirm = (Button) findViewById(R.id.add);    /confirm/i.setonClickListener(new onClickListener() {    public void onClick(View v) {    EditText playername = (EditText) findViewById(R.id.userinput);    playerList.add(playername.getText().toString());    adapter.notifyDataSetChanged();    playername.setText("");    }});} else {       // do nothing}

您应在而

onClickListener

    Button confirm = (Button) findViewById(R.id.add);    /confirm/i.setonClickListener(new onClickListener() {        public void onClick(View v) { EditText playername = (EditText) findViewById(R.id.userinput); if(playerList.size() < 10) {    playerList.add(playername.getText().toString());    adapter.notifyDataSetChanged();    playername.setText(""); } else {     // do nothing }        }     });