Question

 @Override
public boolean onOptionsItemSelected(MenuItem item) {
    Boolean set = false;
    switch (item.getItemId()){
        case R.id.background1:
            mainLayout.setBackgroundResource(R.drawable.redpinkgradientbackground);
            set = true;
            if (set){
                Toast.makeText(getApplicationContext(), "Background already set", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(getApplicationContext(), "Background set", Toast.LENGTH_SHORT).show();
            }
            return true;
        case R.id.background2:
            mainLayout.setBackgroundResource(R.drawable.redgradientbackground);
            set = true;
            if (set){
                Toast.makeText(getApplicationContext(), "Background already set", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(getApplicationContext(), "Background set", Toast.LENGTH_SHORT).show();
            }
            return true;
        case R.id.background3:
            mainLayout.setBackgroundResource(R.drawable.greengradientbackground);
            return true;
        case R.id.background4:
            mainLayout.setBackgroundResource(R.drawable.blackgreygradientbackground);
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

我试图让用户知道什么时候设置了背景，所以当有人选择背景时，它会显示一个带有文本的祝酒词，它已经被设置为背景＆＃39; ，当选择另一个背景时，会显示文本＆＃39;背景设置＆＃39;但是当我尝试使用布尔值时，在case语句中设置为true但是当我在我的尝试中它只显示2个吐司应用

Answer 1

试试

private int selectedBackgroundId = -1;

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()){
        case R.id.background1:
            mainLayout.setBackgroundResource(R.drawable.redpinkgradientbackground);
            if (selectedBackgroundId == R.id.background1){
                Toast.makeText(getApplicationContext(), "Background already set", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(getApplicationContext(), "Background set", Toast.LENGTH_SHORT).show();
            }
            selectedBackgroundId = R.id.background1;
            return true;
        case R.id.background2:
            mainLayout.setBackgroundResource(R.drawable.redgradientbackground);
            if (selectedBackgroundId == R.id.background2){
                Toast.makeText(getApplicationContext(), "Background already set", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(getApplicationContext(), "Background set", Toast.LENGTH_SHORT).show();
            }
            selectedBackgroundId = R.id.background2;
            return true;
        case R.id.background3:
            mainLayout.setBackgroundResource(R.drawable.greengradientbackground);
                if (selectedBackgroundId == R.id.background3){
                    Toast.makeText(getApplicationContext(), "Background already set", Toast.LENGTH_SHORT).show();
                }else{
                    Toast.makeText(getApplicationContext(), "Background set", Toast.LENGTH_SHORT).show();
                }
            selectedBackgroundId = R.id.background3;
            return true;
        case R.id.background4:
            mainLayout.setBackgroundResource(R.drawable.blackgreygradientbackground);
            if (selectedBackgroundId == R.id.background4){
                Toast.makeText(getApplicationContext(), "Background already set", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(getApplicationContext(), "Background set", Toast.LENGTH_SHORT).show();
            }
            selectedBackgroundId = R.id.background4;
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

不是很优雅，但会做到这一点。

如何检查背景是否已设置？

1 个答案: