Android--AlertDialog(2)单选

 public class MainActivity extends AppCompatActivity implements View.OnClickListener{
  
      private TextView text_out,text1;
      
     @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main_activity);
 
         initView();
        
     }
 
     private void initView() {
         text_out=findViewById(R.id.text_out);
         text1=findViewById(R.id.text1);
         text_out.setOnClickListener(this);
     }
 
      int index=0;
     public void onClick(View view){
        AlertDialog.Builder builder =new AlertDialog.Builder(this);
        String[] showMsg = new String[]{"小号","中号","大号","超大号"};
        int[] textSize =new int[]{10,20,30,40};
        builder.setTitle("修改文本大小")
        .setSingleChoiceItems(showMsg, index, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                index=i;
                text1.setTextSize(textSize[index]);
            }
        })
           .setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                text1.setTextSize(textSize[index]);

            }
        })
        setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
             public void onClick(DialogInterface dialogInterface, int i) {
             dialogInterface.dismiss();
            }
         });
         AlertDialog adialog= builder.create();
         adialog.show();
    }  
 }