布局文件main.xml:
package org.lxh.demo; import android.app.Activity; import android.os.Bundle; import android.text.Editable; import android.text.TextWatcher; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; public class Hello extends Activity { EditText searchEditText; Button clearButton; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); searchEditText = (EditText) findViewById(R.id.searchEditText); clearButton = (Button) findViewById(R.id.button_clear); searchEditText.addTextChangedListener(mTextWatcher); clearButton.setOnClickListener(new OnClickListener() { public void onClick(View v) { searchEditText.setText(""); } }); } TextWatcher mTextWatcher = new TextWatcher() { public void onTextChanged(CharSequence s, int start, int before, int count) { // TODO Auto-generated method stub } public void beforeTextChanged(CharSequence s, int start, int count, int after) { // TODO Auto-generated method stub } public void afterTextChanged(Editable s) { if (searchEditText.getText().toString() != null && !searchEditText.getText().toString().equals("")) { clearButton.setVisibility(View.VISIBLE); } else { clearButton.setVisibility(View.INVISIBLE); } } }; }

界面丑的一米,功能是实现了。
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