Question

刚刚开始Android开发，我无法弄清楚为什么它不会起作用。这是我得到的错误（粗体块引用前的最后一行）：

    package com.ample.ballv2;

    import java.util.Random;

    import android.support.v7.app.ActionBarActivity;
    import android.support.v7.app.ActionBar;
    import android.support.v4.app.Fragment;
    import android.os.Bundle;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.view.ViewGroup;
    import android.widget.Button;
    import android.widget.Toast;
    import android.os.Build;

    public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }
    Button answer = (Button) findViewById(R.id.answerbutton);
    answer.setOnClickListener(answerL);
}
private OnClickListener answerL = new OnclickListener(){
public void onClick(view v) {
Random token = random();
int tokenno = token.nextInt(10);
CharSequence ans = "";
switch(tokenno)
{case 0:ans=getString(R.string.msg0);break;
case 1: ans=getString(R.string.msg1);break;
case 2: ans=getString(R.string.msg2);break;
case 3: ans=getString(R.string.msg3);break;
case 4: ans=getString(R.string.msg4);break;
case 5: ans=getString(R.string.msg5);break;
case 6: ans=getString(R.string.msg6);break;
case 7: ans=getString(R.string.msg7);break;
case 8: ans=getString(R.string.msg8);break;
case 9: ans=getString(R.string.msg9);break;
case 10:ans=getString(R.string.msg10);break;

}
Context context = getApplicationContext();
Toast msg = Toast.makeText(context,ans,Toast.LENGTH_LONG);
msg.show();
 }
}//error's popping up here

＆GT;描述资源路径位置类型语法错误，插入＆＃34;;＆＃34;完成FieldDeclaration MainActivity.java / 8ballv2 / src / com / ample / ballv2第56行Java问题

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container,
                false);
        return rootView;
    }
}

}

Answer 1

好吧，我在IDE中尝试了你的代码，问题 - 在提供的示例中 - 是在变量声明中：

private OnClickListener answerL = new OnClickListener(){
     public void onClick(view v) {
           Random token = random();
           int tokenno = token.nextInt(10);
           CharSequence ans = "";
           switch(tokenno) {
                case 0:ans=getString(R.string.msg0);break;
                case 1: ans=getString(R.string.msg1);break;
                case 2: ans=getString(R.string.msg2);break;
                case 3: ans=getString(R.string.msg3);break;
                case 4: ans=getString(R.string.msg4);break;
                case 5: ans=getString(R.string.msg5);break;
                case 6: ans=getString(R.string.msg6);break;
                case 7: ans=getString(R.string.msg7);break;
                case 8: ans=getString(R.string.msg8);break;
                case 9: ans=getString(R.string.msg9);break;
                case 10:ans=getString(R.string.msg10);break;
            }
            Context context = getApplicationContext();
            Toast msg = Toast.makeText(context,ans,Toast.LENGTH_LONG);
            msg.show();
      }
}//here should be ';'

发生这种情况是因为View.OnClickListener具有带方法的主体。如果没有方法（例如，您创建了

私有类MyOnClickListener实现OnClickListener

（http://developer.android.com/reference/android/view/View.OnClickListener.html）那会是这样的：

private MyOnClickListener answerL = new MyOnClickListener(); //<- semicolon here.

您可以在将来使用autoformating工具（在Android / ADT中默认使用ctrl + shift + f和在AndroidStudio中使用ctrl + alt + l（或类似））或在方法之前/之后严格声明类字段。

希望有所帮助）

Answer 2

正如它说你需要在那里插入一个分号，因为你在这里声明了一个字段。所以这就应该是

private OnClickListener answerL = new OnclickListener(){
    public void onClick(view v) {
    ...............
    }//onClick ends here
}; //OnClickListener  ends here

Answer 3

OnclickListener是interface，你应该像这样创建它的对象：

private OnClickListener answerL = new OnclickListener(){
    public void onClick(view v) {
        //do stuffs here
    }
 };

请注意最后的semi-colon。

setOnclickListener请按钮帮助

3 个答案: