Question

抱歉让你讨厌，但我是迈向Android编程的第一步，需要你的支持问题是，我想使用下一个和上一个按钮在照片之间切换我有3张照片和2个按钮（下一个和上一个）当我开始我的应用程序时放我应该按两次下一步按钮来更改照片也在之前我应该按两次更改回来希望有人帮我改进代码

 public class SabahList extends AppCompatActivity  {
 ImageView img;
 int[] mario = new int[]{R.drawable.image_a,R.drawable.image_b,R.drawable.image_c};
 int n =0;


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

    img= (ImageView)findViewById(R.id.imageView2);

}

public void btu_next(View view) {
    img.setImageResource(mario[n]);
    if(n<2)

        n++;
}

public void btu_prev(View view) {
    img.setImageResource(mario[n]);
    if(n>0)
        n--;
}
}

Answer 1

这是你的逻辑问题。你的按钮的功能命令他们先设置资源，然后增加/减少值，因此当你第二次点击它时，它将被设置为先前/逐渐增加。

public void btu_next(View view) {
   if(n < 2)
      n++;

   img.setImageResource(mario[n]);
}

Answer 2

如果您使用来自drawable

的普通数组添加图像，此答案可能对您有所帮助

 //Your xml like this

        <?xml version="1.0" encoding="utf-8"?>
        <LinearLayout
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context="com.devobal.quitchet.SabahList"
            android:orientation="vertical">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center">

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@+id/previous"
                android:text="previous"/>
            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@+id/next"
                android:text="next"/>
            </LinearLayout>

            <ImageView
                android:id="@+id/imageView2"
                android:layout_width="match_parent"
                android:layout_height="match_parent" />
        </LinearLayout>

    //And your Activity like this
        public class SabahList extends AppCompatActivity {
            ImageView imageView2;
            Button previous,next;
            int i=0;
            private int[] textureArrayWin = {R.drawable.star1,R.drawable.star2, R.drawable.star3,};

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_sabah_list);
                imageView2 = (ImageView)findViewById(R.id.imageView2);
                previous  = (Button)findViewById(R.id.previous);
                next = (Button)findViewById(R.id.next);
                if(i==0){
                    previous.setVisibility(View.GONE);
                }
                if (i==2){
                    next.setVisibility(View.GONE);
                }

                previous.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        imageView2.setImageResource(textureArrayWin[i]);
                        i--;
                        if(i==0){
                            previous.setVisibility(View.GONE);} else{ previous.setVisibility(View.VISIBLE);}
                        if (i==2){
                            next.setVisibility(View.GONE);
                        } else{next.setVisibility(View.VISIBLE)}
                    }
                });

                next.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        //if you are loading from bitmap
                        imageView2.setImageResource(textureArrayWin[i]);
                        i++;
                        if(i==0){
                            previous.setVisibility(View.GONE); } else {previous.setVisibility(View.VISIBLE); }
                        if (i==2){
                            next.setVisibility(View.GONE);
                        } else{next.setVisibility(View.VISIBLE)}
                    }
                });
            }
        }

如何使用下一个和上一个按钮更改图像？

2 个答案: