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) {

            }
        });

我得到一个stackoverflow错误.如果我完全删除了v2的textwatcher代码.v1的文本观察器完美地工作..我只是想让我所有的edittext与textwatcher一起工作.我错过了什么？我应该改变什么？

继承logcat

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v1和v2之间创建无限循环的文本更改.

只要您编辑V1的东西,它是TextWatcher集V2的文本这反过来又触发了onTextChanged()您的V2的的TextWatcher.现在,v2 TextWatcher设置v1 的文本(onTextChanged()再次触发你的v1).这将创建一个永无止境的循环,您将获得StackOverflow异常.

您必须更改代码流.

编辑:我正在展示一个例子,如何摆脱两个EditText字段的StackOverflow错误.您可以根据需要对尽可能多的EditTexts进行类似的编码.

首先,您可以像这样扩展TextWatcher(这将帮助您保持代码组织.并且,您可以对所有EditTexts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) {

        }
    }

诀窍是在调用之前删除onTextChangeListeners setText().然后,在完成设置文本后再将它们添加回来.

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) {

        }
    }
}