android - Textwatcher 给出 Stackoverflow 错误

Question

我正在制作一个使用 TextWatcher 的长度转换器。缩短的代码是

 v1.addTextChangedListener(new TextWatcher() {

         @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                val1=Double.parseDouble(v1.getText().toString()); 
                val2=InchToCm(val1); 
                val3=InchToMl(val1);
                val4=InchToKm(val1);
                val5=InchToM(val1);
                val6=InchToY(val1);
                val7=InchToFt(val1);
                val8=InchToLg(val1);
                val9=InchToLgn(val1);
                val11=InchTomm(val1);
                val12=InchToNm(val1);


                v2. setText(Double.toString(val2)); 
                v3. setText(Double.toString(val3)); 
                v4. setText(Double.toString(val4)); 
                v5. setText(Double.toString(val5)); 
                v6. setText(Double.toString(val6)); 
                v7. setText(Double.toString(val7)); 
                v8. setText(Double.toString(val8));
                v9. setText(Double.toString(val9)); 
                v11. setText(Double.toString(val11)); 
                v12. setText(Double.toString(val12));

            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });
     v2.addTextChangedListener(new TextWatcher() {

         @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                val2=Double.parseDouble(v2.getText().toString()); 
                val1=CmToInch(val2);
                val3=CmToMl(val2);
                val4=CmToKm(val2);
                val5=CmToM(val2);
                val6=CmToY(val2);
                val7=CmToFt(val2);
                val8=CmToLg(val2);
                val9=CmToLgn(val2);
                val11=CmTomm(val2);
                val12=CmToNm(val2);

                v1. setText(Double.toString(val1)); 
                v3. setText(Double.toString(val3)); 
                v4. setText(Double.toString(val4)); 
                v5. setText(Double.toString(val5)); 
                v6. setText(Double.toString(val6)); 
                v7. setText(Double.toString(val7)); 
                v8. setText(Double.toString(val8));
                v9. setText(Double.toString(val9)); 
                v11. setText(Double.toString(val11)); 
                v12. setText(Double.toString(val12));

            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

我收到一个 stackoverflow 错误。如果我完全删除 v2 的 textwatcher 代码。v1 的文本观察器工作完美..我只希望我所有的 edittext 都能与 textwatcher 一起使用。我缺少什么？我应该改变什么？

这是日志

08-20 20:31:28.122: E/AndroidRuntime(30377): FATAL EXCEPTION: main
08-20 20:31:28.122: E/AndroidRuntime(30377): java.lang.StackOverflowError
08-20 20:31:28.122: E/AndroidRuntime(30377):    at           android.text.TextUtils.getChars(TextUtils.java:77)
08-20 20:31:28.122: E/AndroidRuntime(30377): android.text.TextUtils.indexOf(TextUtils.java:110)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at     android.text.StaticLayout.generate(StaticLayout.java:182)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.text.DynamicLayout.reflow(DynamicLayout.java:284)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.text.DynamicLayout.<init>(DynamicLayout.java:170)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.makeSingleLayout(TextView.java:6078)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.makeNewLayout(TextView.java:5976)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.checkForRelayout(TextView.java:6515)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.setText(TextView.java:3787)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.setText(TextView.java:3645)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.EditText.setText(EditText.java:80)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.setText(TextView.java:3620)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at com.tdx.simplelegthconverter.MainActivity$1.onTextChanged(MainActivity.java:55)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.sendOnTextChanged(TextView.java:7338)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.setText(TextView.java:3790)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.setText(TextView.java:3645)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.EditText.setText(EditText.java:80)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at android.widget.TextView.setText(TextView.java:3620)
08-20 20:31:28.122: E/AndroidRuntime(30377):    at   com.tdx.simplelegthconverter.MainActivity$2.onTextChanged(MainActivity.java:95)

Answer 1

您正在创建 v1 和 v2 之间无限循环的文本更改。

每当您在 v1 中编辑某些内容时，TextWatcher 会设置 v2 的文本，进而触发 v2 的 TextWatcher 的 onTextChanged() .现在，v2 的 TextWatcher 设置 v1 的文本(再次触发 v1 的 onTextChanged())。这将创建一个永无止境的循环，您将收到 StackOverflow 异常。

您必须更改代码流。

编辑:我正在展示一个示例，如何消除两个 EditText 字段的 StackOverflow 错误。您可以根据需要对任意数量的 EditText 使用类似的编码。

首先，您可以像这样扩展 TextWatcher(这将帮助您保持代码的组织性。而且，您可以对所有 EditText 使用相同的 TextWatcher):

class MyInputWatcher implements TextWatcher {
        private EditText et;

        private MyInputWatcher(EditText editText) {
            et = editText;
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {

            switch (et.getId()) {
            case R.id.editText1: {
                v2.removeTextChangedListener(watcher2);
                v2.setText(s);// set whatever text you want to set in editText2
                v2.addTextChangedListener(watcher2);
                //add the above 3 lines of code for other EditTexts, too (if any)
                break;
            }
            case R.id.editText2: {
                v1.removeTextChangedListener(watcher1);
                v1.setText(s); // set whatever text you want to set in editText1
                v1.addTextChangedListener(watcher1);

                break;
            }
            }
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    }

诀窍是在调用 setText() 之前删除 onTextChangeListeners。然后，在完成设置文本后将它们添加回去。

声明这些成员变量:

private EditText v1, v2;
private MyInputWatcher watcher1, watcher2;

现在，在 onCreate() 方法中，实现这个:

v1 = (EditText)findViewById(R.id.editText1);
v2 = (EditText)findViewById(R.id.editText2);

watcher1 = new MyInputWatcher(v1);
watcher2 = new MyInputWatcher(v2);

v1.addTextChangedListener(watcher1);
v2.addTextChangedListener(watcher2);

为了方便起见，整个 Activity 类如下所示:

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;

public class MainActivity extends ActionBarActivity {

    EditText v1, v2;
    private MyInputWatcher watcher1, watcher2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        v1 = (EditText)findViewById(R.id.editText1);
        v2 = (EditText)findViewById(R.id.editText2);

        watcher1 = new MyInputWatcher(v1);
        watcher2 = new MyInputWatcher(v2);

        v1.addTextChangedListener(watcher1);
        v2.addTextChangedListener(watcher2);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    class MyInputWatcher implements TextWatcher {
        private EditText et;

        private MyInputWatcher(EditText editText) {
            et = editText;
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {

            switch (et.getId()) {
            case R.id.editText1: {
                v2.removeTextChangedListener(watcher2);
                v2.setText(s);// set whatever text you want to set in editText2
                v2.addTextChangedListener(watcher2);
                break;
            }
            case R.id.editText2: {
                v1.removeTextChangedListener(watcher1);
                v1.setText(s); // set whatever text you want to set in editText1
                v1.addTextChangedListener(watcher1);

                break;
            }
            }
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    }
}