Question

我有一个弹出文本视图，下一个按钮和onClick我想切换内容。这就是我试过的......无法让它发挥作用。我得到的错误是类型不匹配无法从void转换为int

    package com.jibushi;



    import android.app.Activity;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.view.ViewGroup;
    import android.widget.Button;
    import android.widget.TextView;

    public class LessonsShell extends Activity{
    private static final int MESSAGE_SHOW_POPUP=7;
    private static final long TIME_DELAY=1000;//1 seconds
    private View view;
    private Button nextButton;
    private Button skipButton;
    private TextView nextSwitch;
    private int tutStrings;
    private int tutStrings2;
    private int tutStrings3;
    private Handler handler = new Handler() {
       public void handleMessage(Message msg) {
          switch(msg.what) {
            case MESSAGE_SHOW_POPUP:
               view();
               break;
           }
       };
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.layout.lessons);
        //this will send a message to the handler to display the popup after 1 seconds.
        handler.sendEmptyMessageDelayed(MESSAGE_SHOW_POPUP,TIME_DELAY);

        nextSwitch = (TextView) findViewById(R.id.lessonsDialog);
        tutStrings = nextSwitch.setText(R.string.lessons_introduction); //type mismatch cannot convert from void to int
        tutStrings2 = nextSwitch.setText(R.string.lessons_introduction2); //type mismatch cannot convert from void to int
        tutStrings3 = nextSwitch.setText(R.string.lessons_introduction3); //type mismatch cannot convert from void to int

        this.nextButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
                switch (v.getId()) {
                    case tutStrings:
                    nextSwitch.setText(R.string.lessons_introduction2);
                    break;

                    case tutStrings2:
                    nextSwitch.setText(R.string.lessons_introduction3);
                    break;
                }
            }
        });

    }

    private void view() {
    // TODO Auto-generated method stub
     ViewGroup parent = (ViewGroup) findViewById(R.id.lessons_bg);
     view = LayoutInflater.from(getBaseContext()).inflate(R.layout.lessons_dialog,                 null);
     parent.addView(view);
    }

    public Button getSkipButton() {
        return skipButton;
    }

    public void setSkipButton(Button skipButton) {
        this.skipButton = skipButton;
        skipButton.findViewById(R.id.skip_button);


    }

    public Button getNextButton() {
        return nextButton;
    }

    public void setNextButton(Button nextButton) {
        this.nextButton = nextButton;
        nextButton.findViewById(R.id.next_button);
    }


    }

是的，缺乏研究。不知道字符串数组......终于搞定了！

    package com.jibushi;



    import android.app.Activity;
    import android.content.res.Resources;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.Button;
    import android.widget.TextView;

    public class LessonsShell extends Activity{
    private static final int MESSAGE_SHOW_POPUP=7;
    private static final long TIME_DELAY=1000;//1 seconds
    private View view;

    private int count = 0;
    private TextView lessonsDialog;
    private String[] lessonDialogString;

    private Handler handler = new Handler() {
       public void handleMessage(Message msg) {
          switch(msg.what) {
            case MESSAGE_SHOW_POPUP:
               view();
               break;
           }
       };
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

    setContentView(R.layout.lessons);
    //this will send a message to the handler to display the popup after 1 seconds.
    handler.sendEmptyMessageDelayed(MESSAGE_SHOW_POPUP,TIME_DELAY);

    }

    private void view() {
    // TODO Auto-generated method stub
     ViewGroup parent = (ViewGroup) findViewById(R.id.lessons_bg);
     view = LayoutInflater.from(getBaseContext()).inflate(R.layout.lessons_dialog,                 null);
     parent.addView(view);

     lessonsDialog = (TextView) findViewById(R.id.lessonsDialog);

     Resources res = getResources();
     myString = res.getStringArray(R.array.lessons_dialog_array); 

     Button nextButton = (Button) findViewById(R.id.next_button);
     nextButton.setOnClickListener(new View.OnClickListener() {
         public void onClick(View view) {
             if (count < lessonDialogString.length) {
                 lessonsDialog.setText(lessonDialogString[count]);
                 count++;
             }
         }
     });

    }
    }

Answer 1

这里有一些问题。

我不知道你在这里要做什么：

nextSwitch = (TextView) findViewById(R.id.lessonsDialog);
tutStrings = nextSwitch.setText(R.string.lessons_introduction); //type mismatch cannot convert from void to int
tutStrings2 = nextSwitch.setText(R.string.lessons_introduction2); //type mismatch cannot convert from void to int
tutStrings3 = nextSwitch.setText(R.string.lessons_introduction3); //type mismatch cannot convert from void to int

TextView.setText(String)没有返回值，因此这些行没有任何意义。你是想自己保存字符串吗？

此外，您的onClick方法也存在问题。传递给View的{{1}}是点击的实际onClick，在这种情况下将是view。在您的代码中，您将切换未定义的整数，而不是您活动中不同视图的ID。

而是做这样的事情：

nextButton

然后，您只需定义void onClick(View v){ switch(v.getId()){ case R.id.next_button: setTextViewNextString(); break; case R.id.prev_button: setTextViewPrevString(); }和setTextViewNextString()方法

Answer 2

方法setText返回void：

public final void setText（int resid）

（来自http://developer.android.com/reference/android/widget/TextView.html#setText%28int%29）

您不能将void分配给int变量。这些行

tutStrings = nextSwitch.setText(R.string.lessons_introduction); //type mismatch cannot convert from void to int
tutStrings2 = nextSwitch.setText(R.string.lessons_introduction2); //type mismatch cannot convert from void to int
tutStrings3 = nextSwitch.setText(R.string.lessons_introduction3); //type mismatch cannot convert from void to int

错了。

我认为你可以用这种方式解决问题：

1）将ID保存在私有变量中：

tutStrings = R.string.lessons_introduction;
tutStrings2 = R.string.lessons_introduction2;
tutStrings3 = R.string.lessons_introduction3;

2）保存字符串，从资源中获取字符串：

private String s1, s2, s3;

...

s1 = this.getString(R.string.lessons_introduction);
s2 = this.getString(R.string.lessons_introduction2);
s3 = this.getString(R.string.lessons_introduction3);

3）现在您可以使用onClick方法：

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId()) {
    case tutStrings:
        nextSwitch.setText(s2);
        break;

    case tutStrings2:
        nextSwitch.setText(s3);
        break;

    }
}

Answer 3

抱歉，我缺乏研究。使用的字符串数组..完美无缺！

Answer 4

像这样更改您的代码：

tutStrings = this.getString(R.string.lessons_introduction);
tutStrings2 = this.getString(R.string.lessons_introduction2); 
tutStrings3 = this.getString(R.string.lessons_introduction3);

请注意：在onClick中，您必须将this替换为您的班级名称，例如Myclass.getString或仅删除this.

创建一个“下一步”按钮，用于切换TextView的内容

4 个答案: