java - Eclipse：edittext 更改了侦听器，edittext 长度为微调器项

Question

我有这个代码：

public class SentSMSActivity extends Activity {

    private Button btnSend;
    private EditText etPlain, etCipher, etDest, key2;
    private String plaintext, tempCipher = null, ciphertext = "";
    private int keyRF, keyCaesar;
    private CheckBox cbEncrypt;
    private String dest, msgSend;
    private Spinner sp;
    private String numbers[];
    private ArrayAdapter<String> adapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sentsms_activity);
        btnSend = (Button) findViewById(R.id.btnSent);
        etPlain = (EditText) findViewById(R.id.etPlainSent);
        etDest = (EditText) findViewById(R.id.etDestSent);
        key2 = (EditText) findViewById(R.id.etKey2Sent);
        cbEncrypt = (CheckBox) findViewById(R.id.cbEnc);
        sp = (Spinner) findViewById(R.id.spKey1);
        //      String numbers[] = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
        //              "10", "11", "12", "13", "14", "15", "16", "17", "18", "19",
        //              "20", "21", "22", "23", "24", "25" };

        key2.setEnabled(false);
        keyRF = 2;

        final TextWatcher textWatcher = new TextWatcher() {

            @Override
            public void beforeTextChanged(CharSequence charSequence, int i,
                    int i1, int i2) {
            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1,
                    int i2) {
            }

            @Override
            public void afterTextChanged(Editable editable) {

                for (int k = 0; k < etPlain.length() - 1; k++) {
                    numbers[k] = String.valueOf(k);
                }
            }
        };

        //third, we must add the textWatcher to our EditText

        sp.setClickable(false);
        cbEncrypt
                .setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

                    @Override
                    public void onCheckedChanged(CompoundButton buttonView,
                            boolean isChecked) {
                        if (cbEncrypt.isChecked()) {
                            key2.setEnabled(true);
                            sp.setClickable(true);
                            etPlain.addTextChangedListener(textWatcher);
                            adapter = new ArrayAdapter<String>(
                                    SentSMSActivity.this,
                                    android.R.layout.simple_spinner_item,
                                    numbers);
                            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                            sp.setAdapter(adapter);
                        } else {
                            key2.setText("");
                            key2.setEnabled(false);
                            sp.setClickable(false);
                        }
                    }
                });
    }
}

它应该用edittext字符串中的数字制作一个微调器，但是在运行时它会给出如下错误：

02-06 20:02:21.205: E/AndroidRuntime(513): FATAL EXCEPTION: main
02-06 20:02:21.205: E/AndroidRuntime(513): java.lang.NullPointerException
02-06 20:02:21.205: E/AndroidRuntime(513):  at java.util.Arrays$ArrayList.<init>(Arrays.java:47)
02-06 20:02:21.205: E/AndroidRuntime(513):  at java.util.Arrays.asList(Arrays.java:169)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:125)
02-06 20:02:21.205: E/AndroidRuntime(513):  at com.hery.androidkripto.SentSMSActivity$2.onCheckedChanged(SentSMSActivity.java:97)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.widget.CompoundButton.setChecked(CompoundButton.java:124)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.widget.CompoundButton.toggle(CompoundButton.java:86)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.widget.CompoundButton.performClick(CompoundButton.java:98)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.view.View$PerformClick.run(View.java:9080)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.os.Handler.handleCallback(Handler.java:587)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.os.Handler.dispatchMessage(Handler.java:92)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.os.Looper.loop(Looper.java:123)
02-06 20:02:21.205: E/AndroidRuntime(513):  at android.app.ActivityThread.main(ActivityThread.java:3683)
02-06 20:02:21.205: E/AndroidRuntime(513):  at java.lang.reflect.Method.invokeNative(Native Method)
02-06 20:02:21.205: E/AndroidRuntime(513):  at java.lang.reflect.Method.invoke(Method.java:507)
02-06 20:02:21.205: E/AndroidRuntime(513):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-06 20:02:21.205: E/AndroidRuntime(513):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-06 20:02:21.205: E/AndroidRuntime(513):  at dalvik.system.NativeStart.main(Native Method)

我对这个错误很困惑，已经尝试解决了3个小时没有任何进展，所以我希望一些成员能给我一个解决方案。

问题：带有来自edittext字符串长度的数字项的微调器

感谢用户 vetal-lebed 回答：

public class MyActivity extends Activity {
private ArrayList <String> list = new ArrayList<String>();
private EditText et;
private Spinner spinner;
private ArrayAdapter<String> adapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    spinner = (Spinner)findViewById(R.id.spinner);
    et = (EditText)findViewById(R.id.et);
    et.addTextChangedListener(watcher);
    adapter = new ArrayAdapter<String>(MyActivity.this,android.R.layout.simple_spinner_item, list);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);
}


private TextWatcher watcher = new TextWatcher() {
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
    public void onTextChanged(CharSequence s, int start, int before, int count) {}

    public void afterTextChanged(Editable s) {
        for (int i = 0; i < s.length(); i ++){
            list.add(String.valueOf(s.charAt(i)));
            adapter.notifyDataSetChanged();
        }
    }
};

}

并感谢其他成员

Answer 1

因为您没有为数组“数字”分配内存。您应该执行以下操作：

numbers = new String[0];

在您的 afterTextChanged() 方法中，您应该创建具有所需长度的新数组（您可以从可编辑中获取它）。然后您可以初始化数组的所有元素并从适配器调用 notifyDataSetChanged()。

UPD

public class MyActivity extends Activity {
private ArrayList <String> list = new ArrayList<String>();
private EditText et;
private Spinner spinner;
private ArrayAdapter<String> adapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    spinner = (Spinner)findViewById(R.id.spinner);
    et = (EditText)findViewById(R.id.et);
    et.addTextChangedListener(watcher);
    adapter = new ArrayAdapter<String>(MyActivity.this,android.R.layout.simple_spinner_item, list);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);
}


private TextWatcher watcher = new TextWatcher() {
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
    public void onTextChanged(CharSequence s, int start, int before, int count) {}

    public void afterTextChanged(Editable s) {
        for (int i = 0; i < s.length(); i ++){
            list.add(String.valueOf(s.charAt(i)));
            adapter.notifyDataSetChanged();
        }
    }
};

}

Answer 2

看起来数字在调用 onCheckedChange() 之前尚未初始化

Answer 3

初始化数组时使用以下代码

ArrayList lst = new ArrayList();